Discuss the anatomy of the popliteal fossa, and include an account the boundaries, structures entering and leaving at each boundary, vascular supply, innervation, ligaments, bones, contents, lymphatics, muscles, and relationships. (12 pts)

General comments

• Posterior to knee, diamond shaped, fat filled, passage of key structures to the lower limb

Boundaries, bones, ligaments, crossing structures, vasculature

• Superior boundary - apex of diamond formed by semimembranosus and semitendinosus diverging from biceps femoris
  • sciatic n. - enters from posterior thigh deep to hamstrings, divides into tibial (medial) and common peroneal (lateral) nn.
• Superior lateral boundary - biceps femoris
  • superior lateral genicular a.v. - leaves popliteal fossa femur at lateral femoral epicondyle superior to origin of gastrocnemius and deep to biceps femoris
• Superior medial boundary - semitendinosus and semimembranosus
  • superior medial genicular a.v. - leaves popliteal fossa at medial femoral epicondyle superior to adductor tubercle and deep to semimembranosus
• Inferior lateral boundary - lateral head of gastrocnemius
  • inferior lateral genicular a.v. - leaves popliteal fossa crossing posterior surface of popliteus fascia and arcuate ligament, deep to head of gastrocnemius
  • common peroneal n. - leaves popliteal posterior to lateral head gastrocnemius and lateral to neck of fibula
• Inferior medial boundary - medial head of gastrocnemius
  • inferior medial genicular a.v. - leaves popliteal fossa posterior surface of tibia near the plateau, deep to head of gastrocnemius
• Inferior boundary - apex of diamond formed by convergence of the two heads of gastrocnemius
  • posterior tibial a.v. - leaves popliteal fossa deep to the heads of origin of soleus
  • sural aa. - leaves popliteal fossa by entering the bellies of gastrocnemius
  • branches of tibial n. to the gastrocnemius
• Posterior boundary - popliteal fascia (deep fascia), transition from fascia lata to crural fascia
  • medial and lateral sural nn. - branches for tibial and common peroneal nn.
  • short saphenous v. - pierces popliteal fascia to enter the popliteal v.
• Anterior boundary - femur, tibial plateau, joint capsule, oblique popliteal lig., arcuate lig., popliteus m.
  • popliteal a.v. - enter through adductor hiatus (superior medial anterior in the fossa) as continuation of the femoral vessels; artery deep to vein.
  • middle genicular a. leaves popliteal fossa through the posterior aspect of the joint capsule

Innervation

• branches of the sciatic, tibial, and common peroneal provide sensory innervation to the region
• posterior femoral cutaneous nerve provides cutaneous innervation
• femoral and obturator nerves may, in part, supply the anterior reaches

Key Relations within the fossa

• superficial to deep: sciatic n and branches, femoral v., femoral a.
• arteries of genicular anastomosis applied to capsule and bone

Lymphatic drainage - popliteal lymph nodes

• superficial drainage of leg enters popliteal fossa along with the lesser saphenous v.
• deep drainage of leg enters popliteal fossa along with posterior tibial vessels
• lymph from popliteal fossa ascend along femoral vessels to deep inquinal nodes

Discuss the muscles, ligaments, and nerves involved with flexion, extension, adduction, and abduction of the digits of the foot and relate this to function. Explain why there is more refined movements from flexion than extension of the digits.

General Comment

• Flexion of the digits, relative to extension, is more specific because of the independence of flexor tendons relative to extensor tendons

Primary Flexors

• Flexor Hallucis longus - inserts at base of distal phalanx of digit 1
  • Innervated by the tibial nerve
  • flexes the IP joint plus the MP and ankle joint
  • Origin from posterior compartment of leg - interosseous membrane and fibula
  • crosses ankle inferior to sustentaculum tali and within flexor sheath
  • receives guidance from the sesamoid bones within the lateral and medial heads of the flexor digitorum brevis
• Flexor hallucis brevis - inserts at base of proximal phalanx of digit 1
  • Innervated by the medial plantar nerve
  • flexes the MP joint
  • lateral and medial head each host a sesamoid bone near the head of the first metatarsal
  • sesamoid bones provide a "groove" to guide the tendon of flexor hallucis longus toward the distal phalanx
  • sesamoid bones provide site of attachment for the abductor hallucis and the adductor hallucis
• Flexor digitorum longus - inserts on the base of the distal phalanx of digits 2-4
  • Innervated by the tibial nerve
  • flexes the distal IP joint plus the proximal IP, MP, and ankle
  • lumbricals arise from the medial sides of the the tendons - extend IP and flex MP
  • origin from the posterior compartment of the leg - tibia and interosseous membrane
  • crosses ankle superior to sustentaculum tali and within the flexor sheath
• Flexor digitorum brevis - inserts at the base of the middle phalanx of digits 2-5
  • Innervated by the medial planter nerve
  • flexes the proximal IP joint plus the MP joint
  • origin from the calcaneus - intrinsic to the foot
  • tendons are approximated to planter surface of flexor digitorum longus
  • tendon splits and inserts onto the sides of the base of the middle phalanx
  • the tendon of flexor digitorum longus passes through the split tendon without tethering to the flexor digitorum brevis
  • independent action at the distal and proximal IP joint is preserved relative to the extensors (extensor hood)
• Flexor digiti minimi brevis - inserts at the base of the proximal phalanx of digit 5
  • Innervated by the lateral plantar nerve
  • flexes the the MP joint
  • intrinsic to the foot

Primary Extensors

• Extensor hallucis longus - inserts on the distal and proximal phalanges of digit 1
  • Innervated by the deep peroneal nerve
  • extends the IP joint plus the MP joint plus the ankle
  • origin from the anterior compartment of the leg - tibia and interosseous membrane
  • stabilized by the superior and inferior retinacula
  • tendon receives a lateral attachment at the level of the head of the first metatarsal from extensor hallucis brevis
  • The tendons of extensor hallucis longus and brevis are tethered to each other and can not act independently.
• Extensor hallucis brevis - inserts on the distal and proximal phalanges of digit 1 (via tendon of extensor hallucis longus)
  • Innervated by the deep peroneal nerve
  • extends the IP and MP joint
  • intrinsic to the dorsum of the foot
  • tendon attaches to lateral side of the tendon of extensor hallucis longus or to the proximal phalanx
  • origin is from the anterolateral aspect of the calcaneus
  • has been considered a named slip of extensor digitorum brevis
• Extensor digitorum longus - inserts on the bases of the middle and distal phalanges of digits 2-5 be way of the extensor hood
  • Innervated by the deep peroneal nerve
  • extends the distal and proximal IP joints plus the MP and the ankle joints
  • origin from the anterior compartment of the leg - interosseous membrane and the fibula
  • stabilized by the superior and inferior extensor retinacula
  • tendons receive lateral attachments from the extensor digitorum brevis on digits 2-4 at level of head of metatarsal
  • the combined tendons of the extensor digitorum longus and brevis contribute to the extensor hood
  • extensor hood has a center insertion on the middle phalanx and sends two lateral bands to insert on the sides of the base of the distal phalanx
  • extensor hood also receives fibrous contributions from the lumbricals and the interossei
  • The extensor digitorum longus and brevis are tethered to each other by the extensor hood and can not act independently
• Extensor digitorum brevis - inserts on the extensor hood and, thus, to the bases of the middle and distal phalanges of digits 2-4 (not 5)
  • Innervated by the deep peroneal nerve
  • extends the distal and proximal IP joints plus the MP
  • origin is from the anterolateral aspect of the calcaneus
  • tendons attach to the extensor at the lateral aspect of the extensor digitorum longus at the level of the head of the metatarsals

Abduction

• Dorsal interossei
  • Innervated by the deep branch of the lateral plantar nerve
  • Origin from the margins of the bodies of the metatarsal bones
  • Insertion onto the extensor hood proximal to the lumbricals
  • The extensor hood of the second toe receives two dorsal interossei and, thus, is the reference digit.
  • The first two dorsal interossei close the space between the first and second metatarsals and the second and third metatarsals
  • Bipennate
• Abductor hallucis
  • Innervated by the by the medial plantar nerve
  • Origin from the inferior medial margin of the calcaneus
  • Insertion on the medial base of the proximal phalanx of the great toe
• Abductor digiti minimi
  • Innervated by the deep branch of the lateral plantar nerve
  • Origin from the lateral posterior margin of the calcaneus
  • Insertion on the lateral base of the proximal phalanx of the fifth digit
• First lumbrical
  • Innervated by the superficial branch of the medial plantar nerve
  • Origin from the medial side of the first tendon (second digit) of the flexor digitorum longus
  • Insertion onto the medial dorsal margin of the extensor hood distal to the insertion of the first interosseus

Adduction

• Plantar interossei
  • Innervated by the deep branch of the lateral plantar nerve
  • Origin from the medial margin of the metatarsal bone of the digit that acts
  • Insertion onto the medial dorsal margin of the lateral three extensor hoods proximal to the insertion of the lumbricals
  • Unipennate
• Lateral three lumbricals
  • Innervated by the lateral plantar nerve
  • Origin from the medial side of the tendons of the flexor digitorum longus
  • Insertion onto the medial dorsal margin of the extensor hood distal to the insertion of the interossei
• Adductor hallucis
  • Innervated by the deep branch of the lateral plantar nerve
  • Transverse head origin from the heads of the metatarsals and the deep transverse metatarsal ligament
  • Oblique head origin from the base of the metatarsal bones and the adjacent tarsal bones
  • Insertion onto the lateral posterior base of the proximal phalanx of the great toe

Flex the metatarsophalangeal joints while holding interphalangeal joints in extension

• Lumbricals (4)
  • Tendons of insertion cross the plantar side of the horizontal axis of the metatarsophalangeal joint
    • Flex the metatarsophalangeal joint
  • Insertion onto the medial margin of the extensor hood distal to the insertions of the interossei
    • Extend the proximal and distal interphalangeal joints
  • Holding the IP joints in extension while flexing the MP joint contributes to the execution of a "graceful" grasp
• Interossei (7)
  • Tendons of insertion cross the plantar side of the horizontal axis of the metatarsophalangeal joint
    • Flex the metatarsophalangeal joint
  • Insertion onto the medial margin of the extensor hood proximal to the insertions of the lumbricals
    • Extend the proximal and distal interphalangeal joints
  • Holding the IP joints in extension while flexing the MP joint contributes to the execution of a "graceful" grasp

Additional comments

• It is the relative independence of the flexor tendons and the action of the lumbricals that permit greater specificity of flexion.
• Mesotendons (vincula) drived from tendon sheaths provide vascular and nervous supply to the distal flexor tendons
• The deep and superficial transverse metatarsal ligaments stabilize the heads of the metatarsals and contribute to fine movement.
• Collateral ligaments at the MP and IP joints stablize flexion and extension.

Discuss the structure of the right atrium of the heart, including muscles, innervation, vasculature, valves, relationship to the pericardium, anatomical features, orientation, and function. (12pts)

Orientation, and Function

• Located to the right and anterior within the pericardial sac
• Site for the pooling of caval blood that subsequently enters the right ventricle
• Atrial contraction assists the "sucking" of blood into the right ventricle

Structure

• Quadrangular chamber receiving deoxygenated blood from the superior and inferior vena cava
• The right auricle is a diverticulum at the superior anterior margin
• Sulcus terminalis marks the internal crista terminalis and the sinuatrial node
  • Landmark for location of sinuatrial (SA) node
• Interatrial septum
  • Fossa ovalis - remnant of fetal foramen ovale, a circulatory shunt between the atria
  • Coronary Sinus - landmark for location of Atrioventricular (AV) node
• Openings
  • Atrioventricular ostium
    • Tricuspid valve into the right ventricle
  • Superior vena cava
    • landmark for location of sinuatrial (SA) node
  • Inferior vena cava
    • Ostia of coronary sinus is to the left of IVC
  • Coronary sinus
    • Receives venous blood from the great, middle, and small cardiac veins
  • Anterior cardiac veins
    • Drain directly into right atrium

Muscles

• Crista terminalis - muscle
  • Separates the smooth posterior wall (sinus venarum) from the muscular anterior wall (pectinate mm)
  • Marks the surface projection of the sulcus terminalis
  • Superior extent marks location of sinoatrial node near the superior vena cava
• Pectinate muscle

Innervation

• Sinoatrial node
  • The sinoatrial node is a crescent shaped heart region about 8mm long and located at the superior aspect of the sulcus terminalis within the wall of the right atrium. It is referred to as the pacemaker of the heart owing to its electrical characteristics and crucial role in timing of the cardiac cycle.
  • The SA node connects to the AV node by internodal tracts.

Vasculature

• Right coronary artery
• Marginal branch of right coronary artery
• Sinuatrial artery - nodal branch to SA node
• Anterior cardiac vv
• Small cardiac vv

Valves

• Tricuspid valve (AV Ostium)
  • Supported by the fibrocartilaginous skeleton of the heart
  • Three cusps are held by chordae tendinea that prevent eversion during right ventricular contraction
  • Passively open to the flow of atrial blood into the right ventricle
• Valve of the inferior vena cava
• Valve of the coronary sinus

Relationship to Pericardium

• Reflections of visceral pericardium (epicardium) define the venous mesocardium of the superior and inferior vena cava
  • The visceral pericardium moves against the parietal serous pericardium with the benefit of a layer of serous fluid to reduce friction
• The sinoatrial node is located immediately deep to the epicardium and has access to exogenous autonomic nervous supply at this location

A 25 year old male is the unrestrained driver of a motor vehicle involved in a high speed head on collision. His feet are impacted into the floor. X-rays of the right ankle taken in the Emergency Department reveal a displaced fracture of the calcaneus through the attachments of the calcaneofibular and tibiocalcaneal ligaments. As a 2nd year resident, you are asked to: Review structures related to the medial region of the ankle. Include bones, muscles, fascia, retinacula, innervation, articulation and movements, medial longitudinal arch, as well their anatomic relationship. Also discuss the effects on foot movement(s) and gait. (12 pts)

Explicit Statement of Structures at Risk

• Skin
• Flexor retinaculum (Tom, Dick, and a very Nervous Harry)
  • tibialis posterior tendon
  • flexor digitorum longus
  • posterior tibial artery and vein - superficial to sustentaculum tali
    • medial and lateral plantar arteries
    • medial calcaneal artery
  • tibial nerve
    • lateral and plantar branches
    • medial calcaneal nerve
  • flexor hallucis longus tendon
  • synovial tendon sheaths
• deltoid ligament - anterior tibiotalar, posterior tibiotalar, tibiocalcaneal, and tibionavicular ligaments are components
• abductor hallucis
• medial malleolus of tibia
• talus bone
• calcaneus bone
• navicular bone
• plantar calcaneonavicular ligament (spring ligament)
• talocrural joint
• talocalcaneonavicular joint
• subtalar joint

Bones, Joints, Articulations and Movements

• medial malleolus of tibia
• calcaneus
• talus
• sustentaculum tali
• talocrural joint - flexion and extension of ankle, most stable in extension (dorsiflexion)
• talocalcaneonavicular joint - eversion
• subtalar joint - eversion

Muscles, Movements, and Gait

• flexor digitorum longus - flexion of the DIP, PIP, MP, and ankle
• flexor hallucis longus - flexion of the IP, MP, and ankle
• abductor hallucis - abduction of the great toe
• tibialis posterior - flexion and inversion of the ankle
• mechanical damage to the region is expected to compromise inversion and lead to an everted foot
• nerve damage to the medial and lateral planter nerves will affect push off due to weakened intrinsic muscles of the sole of the foot

Fasciae, Retinaculae, and Ligaments

• flexor retinaculum - supports flexor digitorum longus and flexor hallucis longus, synovial sheaths
• synovial tendon sheaths
• deltoid ligaments and named parts - resists eversion
• plantar calcaneonavicular ligament - supports the medial longitudinal arch

Vasculature and Lymphatic Drainage

• medial branches of malleolar anastomosis for arteries and veins
  • anterior medial malleolar artery
  • posterior medial malleolar artery
  • medial tarsal artery
  • medial calcaneal artery
• great saphenous vein crosses anterior to medial malleolus
• superficial lymphatic drainage primarily follows the great saphenous vein toward superficial inguinal nodes
• deep lymphatic drainage is toward popliteal nodes

Innervation

• tibial nerve
• medial plantar nerve - abductor hallucis, flexor digitorum brevis, the flexor hallucis brevis, and the first Lumbrical
• lateral plantar nerve - the rest of intrinsic muscles
• cutaneous innervation by medial calcaneal nerve
• cutaneous innervation by saphenous nerve

Medial Longitudinal Arch

• Bones
  • calcaneus, head of talus, navicular, cuneiform bones, and first 3 metatarsals (heads of) - labeled drawing was helpful (with discussion)
  • talocalcaneonavicular joint has the head of the talus of as the "keystone" wedged between the calcaneus and navicular
  • spring ligament is the floor of the talocalcaneonavicular joint and acts as a "staple" to approximate the navicular to the calcaneus
• Ligaments
  • spring ligament - plantar calcaneonavicular ligament
    • maintains the head of talus at the peak of the medial longitudinal arch
    • stretching of this ligament allows the navicular bone to move away from the calcaneus; if stretched, the talus falls
  • deltoid ligament
  • minor support by long and short plantar
• Muscles
  • Suspends the arch
    • tibialis posterior - suspends the arch
    • tibialis anterior - suspends the arch
    • extensor hallucis longus - suspends the arch
  • Staples the arch
    • peroneus longus - tendinous insertions staple the arch
      • note: peroneus longus is a tie beam for the transverse arch, a vertical support for the lateral longitudinal arch, and a staple for the medial longitudinal arch
    • tibialis posterior - tendinous insertions staple the arch
    • tibialis anterior - tendinous insertions staple the arch
  • "Tie beam" support - structures serving to approximate the bones of the arch
    • intrinsic mm - adductor hallucis oblique head, flexor hallucis longus, abductor hallucis, flexor digitorum brevis, quadratus plantae, lumbricals
    • extrinsic mm - flexor hallucis longus is key, tibialis posterior, flexor digitorum longus
    • fascia - plantar aponeurosis and septa
    • skin
• Fascial Specializations
  • fascia - plantar aponeurosis and septa
  • skin
• Neural and Vascular Relationships
  • Tibial nerve and posterior tibial artery elaborate medial and lateral plantar arteries and nerves
  • Medial and lateral plantar nerves and vessels pass deep to abductor hallucis to enter plantar region
  • Lateral planter nerve and vessels pass superior to flexor hallucis brevis and inferior to quadratus plantae to reach lateral aspect of sole.
• Consequences of Damage
  • A fallen medial arch indicates failure of the spring ligament to approximate the navicular bone to the calcaneus. As a result, the head of the talus moves inferior into the region traversed by the medial and lateral plantar vessels and nerves. Compression of these structures could lead to cold feet (poor circulation) and paresthesias (compressed nerves).

A 66 year old male is admitted to the general medicine ward service with respiratory failure that requires mechanical ventilation. In discussing the case, it is unclear if it is due to a disease process affecting the muscles of respiration or the nerves that innervate the various mechanisms involved in breathing. In order to understand which structure may be the cause of his respiratory failure your attending physician asks you to: Discuss the mechanics of breathing, focusing on explaining the basic movements (including joints) of the thoracic cage and expansion of the lung in respiration. (12 pts)

Ribs, Joints, and Respiratory Movement

• Ribs
  • True ribs: 1-7
  • False ribs: 8-10
  • Floating ribs: 11-12
• Joints
  • costovertebral - synovial
    • between head of the rib and the same numbered vertebral body, the superior vertebral body, and the intervertebral disc
    • radiate ligaments
  • costotransverse - synovial
    • between tubercle of rib and same numbered transverse process
    • costotransverse ligaments
  • sternochondral - synovial
    • between sternum and chondral cartilages
    • radiate ligaments
  • interchondral - synovial
    • between chondral cartilages
  • costochondral - fibrous (Gray's contends that movement does not occur here)
• Anterior posterior movement
  • pump handle for true ribs
  • cupped tubercle of transverse process results in pump handle of upper ribs
  • costovertebral, costochondral and sternochondral joints involved
  • The pump-handle movement of respiration refers to the movements of the upper 6 ribs during breathing. During inspiration there is an increase in the anterior-posterior diameter of the thorax. The sternum moves superiorly and anteriorly in accord with rib movements occurring at the costovertebral, costotransverse, costochondral, and sternochondral joints. Relative to the lower ribs, the costotransverse joint articulation at the transverse process is cupped and accommodates the tubercle of the rib. This articulation permits the rib to rotate on a transverse axis. A slight downward movement at the head of the rib is amplified distally at the sternum. This movement is transferred to the sternum by the costochondral and sternochondral joints. The result is that the sternum raises on inspiration much like the raising of a pump-handle when drawing water from the depths of a well
• Transverse Movement
  • bucket handle for false ribs
  • planar tubercle of transverse process permits an outward sliding of the rib and results in bucket handle of lower ribs
  • costovertebral, interchondral, costochondral and sternochondral joints involved
• Vertical Movement
  • diaphragmatic
  • phrenic n., pericardiacophrenic vessels, ant. post. intercostal vessels
  • Upon diaphragmatic contraction the height of the diaphragmatic dome drops to increase the vertical extent of the thoracic cavity.
  • Intercostal muscles hold the thoracic wall rigid and thereby increase the effectiveness of diaphragmatic movement.
• Lung Movement
  • capillary effect, negative pressure, etc.
  • pneumothorax - air enters and breaks capillary effect, loss of negative pressure, the lung collapses

General Comments. (Optional)

• The vasculature supply to the thoracic wall travels within the neurovascular plane defined superficially by the internal intercostal muscles and membrane (posterior) and deeply by the subcostal (posterior), innermost intercostal (intermediate), and transversus thoracis (anterior) muscles. The intercostal veins, arteries, and nerves are located inferior to the costal groove of the superior rib defining an intercostal space. From superior to inferior is vein, artery, nerve. Posterior, lateral, and anterior branches of the intercostal vessels and nerves leave the neurovascular plane to supply superficial regions of the thoracic wall. The lateral branches further divide into posterior and anterior branches whereas the anterior branches further divide into medial and lateral branches.

Collateral circulation and structure (Optional)

• The bulk of the anterior vasculature has the subclavian arteries and brachiocephalic veins as the parent vessels whereas the bulk of the posterior vasculature has the descending aorta (first two intercostal spaces excepted) and azygous system as the parent vessels. The anterior and posterior vasculatures anastomose within the thoracic wall. Thus, the aortic arch can deliver blood directly to the descending aorta or indirectly to the descending aorta by way of the anterior vasculature (subclavian to internal thoracic to anterior intercostals to posterior intercostals to descending). See below.
• Borders
  • anterior - sternum (manubrium, body, xiphoid process), chondral cartilages
  • posterior - vertebral bodies
  • lateral - ribs proper
  • superior - thoracic inlets
  • inferior - thoracic outlet
• Vertebral projections
  • sternal notch - T3
  • sternal angle - T4
  • xiphisternal junction - T9
  • inferior extent of costal margin - L3
• Fascial layers at midaxillary line
  1. skin
  2. tela subcutanea
  3. external intercostal
  4. internal intercostal
  5. neurovascular plane (van)
  6. innermost intercostal
  7. endothoracic fascia
  8. fibrous layer parietal costopleura
  9. serous layer of parietal costopleura
• Intercostal muscles - superficial to deep
  • External intercostals - anterior membrane, downward "V"
  • Internal intercostals - posterior membrane upward "V", superficial to neurovascular plane
  • Innermost intercostals - posterior as subcostals, anterior as transversus thoracis, deep to neurovascular plane
• Innervations
  • Motor innervations by intercostal nerves and posterior rami of spinal nerves T1-11
  • Cutaneous innervation described above in General Comments
    • Skin overlying xiphoid process is by spinal nerve T8
  • Autonomic innervation follows intercostal nerves
    • preganglionic cell bodies in IMLCC T1-11, postganglionic cell bodies in thoracic sympathetic trunk ganglia
• Arteries
  • Posterior intercostal spaces
    • 1-2 Supreme (highest) thoracic artery from costocervical trunk of subclavian artery
    • 3-11 Posterior intercostal arteries from the descending aorta
  • Anterior intercostal spaces
    • 1-6 - Internal thoracic artery from subclavian artery
    • 7-9 - Musculophrenic artery from internal thoracic artery
    • 10-11 - Superior epigastric from internal thoracic artery
• Veins
  • Right posterior intercostal spaces
    • 1 - Supreme (highest) intercostal vein from brachiocephalic vein
    • 2-4 - superior intercostal vein from arch of the azygous vein
    • 5-11 - Posterior intercostal veins from azygous vein
  • Left posterior intercostal spaces
    • 1 - Supreme (highest) intercostal vein from brachiocephalic vein
    • 2-4 - superior intercostal vein from accessory hemiazygous vein, or brachiocephalic vein, or coronary sinus
    • 5-11 - Posterior intercostal veins from hemiazygous vein
  • Anterior intercostal spaces
    • 1-6 - Internal thoracic vein
    • 7-9 - Musculophrenic vein
    • 10-11 - Superior epigastric vein

Lymphatic Drainage (Optional)

• Laterally, lymph drainage from the anterior thoracic wall (breast) is into groups of axillary nodes. Most of this drainage is into the pectoral nodes located along pectoral branches of the thoracoacromial vessels. Pectoral nodes drain into the apical nodes located near the apex of the axilla. On the left, the axillary nodes give rise to the subclavian lymphatic trunk. This vessel commonly drains into the thoracic duct and then the angle of internal jugular. The right subclavian duct often drains directly into the venous system. Apical nodes also have drainages into cervical and supraclavicular nodes. Metastatic disease in these nodes is especially difficult to remove.
• The medial aspect of the breast is drained by intercostal vessels into parasternal nodes. Parasternal and paratracheal drainages combine to form the bronchomediastinal lymph trunks. Drainage continues into the right lymphatic duct on the right and the thoracic duct on the left.
• The breast is also drained by subcutaneous vessels. These vessels have a wide distribution ranging from the cervical region to the inguinal region and crossing the midline. If the deeper lymph channels are blocked, as may be the case with cancer, subcutaneous drainage may greatly increase and widely disperse cancerous cells.
• axillary notes receive 75% of lymphatic drainage
  • pectoral nodes - lateral border of pectoralis major
  • apical nodes - beneath the clavicle
  • supraclavicular nodes
  • cervical nodes
• parasternal nodes
  • along the internal thoracic artery
• subcutaneous lymphatics
  • distribute to wide area if deep lymphatics are blocked (e.g. cancer)
• intercostal nodes
  • along the azygous veins in the posterior mediastinum
  • drain posterior intercostal spaces
  • left intercostal nodes may drain directly into thoracic duct
  • right intercostal nodes may find their way to the right lymphatic duct
• left/right differences
  • right side into right (subclavian) lymph duct
  • left side into thoracic duct and left subclavian v.
• Summary.
  • Laterally, lymph drainage from the breast is into groups of axillary nodes. Most of this drainage is into the pectoral nodes located along pectoral branches of the thoracoacromial vessels. Pectoral nodes drain into the apical nodes located near the apex of the axilla. On the left, the axillary nodes give rise to the subclavian lymphatic trunk. This vessel commonly drains into the thoracic duct and then the angle of internal jugular. The right subclavian duct often drains directly into the venous system. Apical nodes also have drainages into cervical and supraclavicular nodes. Metastatic disease in these nodes is especially difficult to remove.
• The medial aspect of the breast is drained by intercostal vessels into parasternal nodes. Parasternal and paratracheal drainages combine to form the bronchomediastinal lymph trunks. Drainage continues into the right lymphatic duct on the right and the thoracic duct on the left.
• The breast is also drained by subcutaneous vessels. These vessels have a wide distribution ranging from the cervical region to the inguinal region and crossing the midline. If the deeper lymph channels are blocked, as may be the case with cancer, subcutaneous drainage may greatly increase and widely disperse cancerous cells.
• Posterior intercostal spaces drain into intercostal nodes located in the posterior mediastinum.

An 18 year old football player is tackled during a football game. He falls to the ground holding his left knee. When reviewing the video replay of the tackle, it is noted that he was struck on the posterior lateral aspect of the knee. On exam, he has "a positive anterior drawer sign" (forward sliding of tibia) and tenderness and laxity (relaxation/looseness) of the medial joint space of the knee when valgus (bending/twisting) stress is placed on it. Discuss the anatomy of the knee joint. Include bones, cartilage, ligaments, muscles, bursa, vascular supply, innervation, stabilization, center of gravity, and locking/unlocking of the knee joint. (12 pts)

Bones and Articulations

• Synovial hinge joint between the femoral and tibial condyles.
• Tibial plateau is cupped by the medial and lateral menisci.
• Femoral condyles - shape
• Tibial condyles - shape
• Patella articulates anteriorly as a sesamoid bone in the quadriceps tendon.
• Articular cartilage
• Superior tibiofibular joint - synovial plane joint

Ligaments

• Medial collateral ligament (attached to medial meniscus).
  • medial femoral epicondyle to the medial tibial condyle.
  • resists abduction of tibia
• Lateral collateral ligament (interval between lateral meniscus and ligament transmits popliteus tendon
  • From lateral femoral epicondyle to the head of the fibula
  • resists adduction of tibia
• Popliteofibular ligament
  • from popliteus tendon to head of fibula
  • resists adduction of tibia
• Anterior cruciate ligament
  • from lateral posterior femoral condyle to anterior aspect of tibial intercondylar eminence.
  • resists forward displacement of the tibia.
  • Alar fold
• Posterior cruciate ligament
  • from posterior medial femoral condyle to posterior aspect of tibial intercondylar eminence.
  • resists posterior displacement of tibia
  • Alar fold
• Oblique popliteal and arcuate ligaments strengthen the posterior joint capsule.
  • Semimembranosus
  • Popliteus
• Coronary, transverse genicular, and meniscofemoral ligaments secure the menisci.
  • Tibial plateau

Cavities and bursae

• Synovial joint cavity
  • attaches to edges of menisci - articular surface is intrasynovial
  • Alar folds anterior to anterior crucial ligament - posterior limit of midsagittal synovial cavity
  • reflections of the synovial membrane along the intercondylar fossa - cruciate ligaments are extrasynovial.
  • continuous with suprapatellar bursa (quadriceps bursa)
    • Articularis genu
• prepatellar bursa
  • bursitis
• infrapatellar bursa
  • Superficial and deep
• Joint Capsule
  • ligaments making up the capsule (above)
  • intercondylar area is extrasynovial
  • popliteus tendon within cavity
  • patellar retinaculum
  • patellar and quadriceps tendon

Muscles, Movements and Limitations of Movement

• Primarily flexion and extension (hinge joint).
• Some rotation (30-40 degrees) is possible when the knee is flexed
• Flexion is primarily by the hamstrings, short head of biceps, gracilis, and sartorius.
  • innervated by tibial portion sciatic, peroneal portion sciatic, obturator, and femoral nerves respectively.
  • minor flexion by popliteus, gastrocnemius, and plantaris.
  • flexion is limited by quadriceps, cruciate ligaments, and by opposing soft tissues (calf and thigh).
• Extension is primarily by the quadriceps and tensor fascia lata.
  • innervation by femoral nerve and superior gluteal nerve.
  • extension is limited by hamstrings, cruciate ligaments, collateral ligaments, posterior joint capsule.
• Medial rotation of tibia is primarily by popliteus, semitendinosus, gracilis, and sartorius.
  • innervation by tibial nerve, tibial portion sciatic, obturator, and femoral nerves respectively.
  • limitation of movement by collateral ligaments
• Lateral rotation of tibia is primarily by biceps femoris.
  • innervation by tibial and peroneal portions of sciatic nerve.
• limitation of movements by collateral ligaments.
  • Abduction and adduction is limited by the medial and lateral collateral ligaments.
• Fascial Specializations
  • patellar retinaculum
  • iliotibial tract
  • investing fascia

Vascular Supply - Genicular Anastomosis

• Superior and inferior, medial and lateral genicular arteries, and middle genicular from the popliteal artery.
  • Middle genicular artery and intercondylar space
• Descending genicular artery from femoral artery and descending branch from lateral femoral circumflex artery.
• Fibular circumflex artery, and anterior and posterior tibial recurrent arteries from the anterior and posterior tibial artery
• Accompanying veins

Lymphatic Supply

• popliteal nodes - receive superficial and deep drainages
• Infections of the lateral foot may cause swelling of popliteal nodes that, in turn, disrupts the contents of the popliteal fossa.

Innervation (Hilton's Law)

• small branches of the femoral, obturator, and sciatic, and tibial nerves pierce the joint capsule.

"Screw Home"

• Consider when the knee is extended with the foot planted on the ground. In this case, the tibia is fixed by virtue of the planted foot. Thus, rotation of the knee occurs as movement of the femur. The femur rotates medially as the knee "locks" in extension. The lateral femoral condyle is smaller than the medial femoral condyle. As the knee is extended the smaller condyle moves through its arc before the medial condyle. Thus, movement stops at the lateral condyle while the femoral medial condyle continues to move further posteriorly. This movement results in a medial rotation of the femur.
• This medial rotation torques the joint capsule and its ligamentous specializations (medial and later collateral ligaments). The "twisting" of the capsular ligaments causes the region to tighten. This firmly approximates the femoral condyles to the tibial plateau and "locks" the knee. The femur "screws" medially onto the tibial plateau due to the larger medial condyle and the twisting of the capsular ligaments. On extension, the knee goes through a "screw home" rotation that results in "close packing."
• The final medial rotation of the femur is driven by the line of gravity moving anterior to the axis of the knee joint. Thus, locking the knee is driven by gravity. Unlocking the knee requires muscular involvement. The popliteus, having lateral superior to medial inferior attachments, posterior to the axis of the knee, can to lateral rotate the femur (reverse origin and insertion) and, thus, unlock the knee joint.

Review structures related to the medial region of the ankle. Include bones, muscles, fascia, retinacula, innervation, articulation and movements, medial longitudinal arch, and anatomic relationships. Also discuss the effects on foot movement(s) and gait. (12 pts)

Explicit Statement of Structures at Risk

• Skin
• Flexor retinaculum (Tom, Dick, and a very Nervous Harry)
  • tibialis posterior tendon
  • flexor digitorum longus
  • posterior tibial artery and vein - superficial to sustentaculum tali * medial and lateral plantar arteries * medial calcaneal artery
  • tibial nerve
    • lateral and plantar branches
    • medial calcaneal nerve
  • flexor hallucis longus tendon
• deltoid ligament - posterior tibiotalar, tibiocalcaneal, and tibionavicular ligaments are components
• Lateral border of abductor hallucis
• medial malleolus of tibia
• talus bone
• calcaneus bone
• navicular bone
• plantar calcaneonavicular ligament (spring ligament)
• talocrural joint
• talocalcaneonavicular joint
• subtalar joint

Bones, Joints, Articulations and Movements

• medial malleolus of tibia
• calcaneus
• talus
• sustentaculum tali
• talocrural joint - flexion and extension of ankle, most stable in extension (dorsiflexion)
• talocalcaneonavicular joint - eversion
• subtalar joint - eversion

Muscles, Movements, and Gait

• flexor digitorum longus - flexion of the DIP, PIP, MP, and ankle
• flexor hallucis longus - flexion of the IP, MP, and ankle
• abductor hallucis - abduction of the great toe
• tibialis posterior - flexion and inversion of the ankle
• mechanical damage to the region is expected to compromise inversion and lead to an everted foot
• nerve damage to the medial and lateral planter nerves will affect push off due to weakened intrinsic muscles of the sole of the foot

Fasciae, Retinaculae, and Ligaments

• flexor retinaculum - supports FDL and FHL, synovial sheaths
• synovial tendon sheaths
• deltoid ligaments and named parts - resists eversion
• plantar calcaneonavicular ligament - supports the medial longitudinal arch

Vasculature and Lymphatic Drainage

• medial branches of malleolar anastomosis for arteries and veins
  • anterior medial malleolar artery
  • posterior medial malleolar artery
  • medial tarsal artery
  • medial calcaneal artery
• great saphenous vein crosses anterior to medial malleolus
• superficial lymphatic drainage primarily follows the great saphenous vein toward superficial inguinal nodes
• deep lymphatic drainage is toward popliteal nodes

Innervation

• tibial nerve
• medial plantar nerve - abductor hallucis, flexor digitorum brevis, the flexor hallucis brevis, and the first Lumbrical
• lateral plantar nerve - the rest of intrinsic muscles
• cutaneous innervation by medial calcaneal nerve
• cutaneous innervation by saphenous nerve

Medial Longitudinal Arch

• Bones
  • calcaneus, head of talus, navicular, cuneiform bones, and first 3 metatarsals (heads of) - labeled drawing was helpful (with discussion)
  • talocalcaneonavicular joint has the head of the talus of as the "keystone" wedged between the calcaneus and navicular
  • spring ligament is the floor of the talocalcaneonavicular joint and acts as a "staple" to approximate the navicular to the calcaneus
• Ligaments
  • spring ligament - plantar calcaneonavicular ligament
    • maintains the head of talus at the peak of the medial longitudinal arch
    • stretching of this ligament allows the navicular bone to move away from the calcaneus; if stretched, the talus falls
  • deltoid ligament
  • minor support by long and short plantar
• Muscles
  • Suspends the arch
    • tibialis posterior - suspends the arch
    • tibialis anterior - suspends the arch
    • extensor hallucis longus - suspends the arch
  • Staples the arch
    • peroneus longus - tendinous insertions staple the arch
      • note: peroneus longus is a tie beam for the transverse arch, a vertical support for the lateral longitudinal arch, and a staple for the medial longitudinal arch
    • tibialis posterior - tendinous insertions staple the arch
    • tibialis anterior - tendinous insertions staple the arch
  • "Tie beam" support - structures serving to approximate the bones of the arch
    • intrinsic mm - adductor hallucis oblique head, flexor hallucis, abductor hallucis, flexor digitorum brevis, quadratus plantae, lumbricals
    • extrinsic mm - flexor hallucis longus is key, tibialis posterior, flexor digitorum longus
    • fascia - plantar aponeurosis and septa
    • skin
• Fascial Specializations
  • fascia - plantar aponeurosis and septa
  • skin
• Neural and Vascular Relationships
  • Tibial nerve and posterior tibial artery elaborate medial and lateral plantar arteries and nerves
  • Medial and lateral plantar nerves and vessels pass deep to abductor hallucis to enter plantar region
  • Lateral planter nerve and vessels pass superior to flexor hallucis brevis and inferior to quadratus plantae to reach lateral aspect of sole.
• Consequences of Damage
  • A fallen medial arch indicates failure of the spring ligament to approximate the navicular bone to the calcaneus. As a result, the head of the talus moves inferior into the region traversed by the medial and lateral plantar vessels and nerves. Compression of these structures could lead to cold feet (poor circulation) and paresthesias (compressed nerves).

Discuss the anatomy of the posterior compartment of the thigh, and include an account of the muscles (origin/insertion), contents and relationships, fascial specializations, innervations, vascular supply, ligaments, bones and articulations, movements and limitations of movements, and stability. (12 pts)

Function

• The hamstring muscles, arising from the ischial tuberosity and inserting on the tibia, are biarticulate. Thus, they act at both the hip (extension) and the knee (flexion). Semimembranosus and semitendinosus are medial rotators of the knee. Biceps femoris is a lateral rotator at the knee.
• The short head of the biceps, a hybrid muscle, crosses one joint -- the knee joint. It is a flexor and a lateral rotator of the knee.
• The posterior adductor magnum crosses one joint -- the hip joint. It is an extensor of the hip.

Boundaries

• Anterior: adductor magnus, femur, vastus lateralis, lateral and medial intermuscular septa
• Posterior: fascia lata
• Lateral: fascia lata, lateral intermuscular septum
• Medial: fascia lata, medial intermuscular septum
• Superior: Gluteal fold
• Inferior: axis of the knee joint (includes superior aspect of popliteal fossa)

Relationships (See Boundaries)

• Deepest in the posterior compartment is the adductor magnus. Perforating arteries pierce the adductor magnus medial to this muscle's insertion along the linea aspera of the femur. The most posterior fibers of adductor magnus extend to the adductor tubercle of the medial femoral epicondyle. The adductor hiatus results from a discontinuity of insertion along the inferior aspect of the linea aspera.
• The semimembranosus and semitendinosus course downward from the ischial tuberosity. Both muscles deviate to the medial side. Semitendinosus crosses posterior to the knee and then turns anterior to insert with the pes anserinus. Semimembranosus is closely applied to the anterior (deep) surface of semitendinosus. It crosses posterior to the knee and inserts on the postero-medial aspect of the medial tibial condyle.
• The long-head of the biceps courses downward from the ischial tuberosity and deviates to the lateral side as it approaches the knee. The tendon of insertion crosses posterior to the knee and inserts on the postero-lateral aspect of the lateral tibial condyle and on the head of the fibula. The short-head of the biceps arises from the middle third of the femur and joins the long-head in the lower one-third of the thigh.
• The sciatic nerve enters the posterior thigh from the gluteal region passing on the anterior (deep) surface of the inferior free edge of the gluteus maximus. It lies lateral to the ischial tuberosity and is applied to the posterior surface of the adductor magnus (medial to femur). The sciatic nerve courses downward between biceps femoris and adductor magnus. At the inferior 1/3 of the thigh the sciatic nerve deviates medially as the biceps deviates laterally. In the superior aspect of the popliteal fossa the sciatic nerve branches into the common peroneal nerve and the tibial nerve.
• The posterior femoral cutaneous nerve of the thigh follows the medial posterior aspect of the sciatic nerve.

Innervations

• The hamstring muscles and the posterior adductor magnus are innervated by the tibial portion of the sciatic nerve. These branches occur in the gluteal region and in the superior thigh. They branch from the medial side of the sciatic nerve. The short head of the biceps receives a lateral branch of the sciatic nerve derived from the peroneal portion.
• The posterior cutaneous nerve of the thigh sends branches posteriorly that pierce the fascia lata to provide cutaneous innervation to the posterior aspect of the thigh as far inferiorly as the lower reaches of the popliteal region.
• The lateral femoral cutaneous nerve and the obturator nerve provide cutaneous innervation to the lateral and medial margins of the posterior aspect of the thigh.

Vasculature and Lymphatic Drainage

• The upper 1/3 of the posterior compartment receives vascular supply from the inferior gluteal, medial and lateral circumflex, and 1st perforating vessels. The sciatic nerve receives the arteria commitans nervi ischiadici from the inferior gluteal vessels. This vessel is subsequently augmented by the perforating vessels and branches of the popliteal vessels.
• The middle 1/3 of the thigh receives the perforating vessels from the profunda femoral vessels. These 4-6 vessels perforate the insertions of the adductor magnus along the medial border of the femur.
• The lower 1/3 of the posterior compartment receives vascular from the popliteal vessels in addition to the lower perforating vessels.
• Deep lymphatic drainage is to deep inguinal nodes.
• Superficial lymphatic drainage is primarily to the vertical group of superficial inguinal nodes.

Definition of the hamstrings

• The hamstring muscles: 1) arise from the ischial tuberosity, 2) are biarticulate (cross two joints), and 3) are innervated by the tibial portion of the sciatic nerve.
• They are the semimembranosus, semitendinosus, and long-head of the biceps femoris

Movements and Limitations of Movements

• adduction: limited by other limb and ligamentum capitus
• abduction: limited by pubofemoral ligament
• flexion: limited by ventrum and hamstring muscles
• extension: limited by iliofemoral ligament
• medial rotation: limited by short rotators of gluteal region
• lateral rotation: limited by pubofemoral and gluteus medius/minimus

Stability

• • The hip joint is maximally stable during extension as is the case during quiet standing. The line of gravity falls behind the axis causing to hip to extend. Capsular thickenings (aforementioned ligaments) spiral from posterior to anterior and from medial on the pelvic girdle to lateral on the femur. As the ligaments tighten the capsule shortens similar to twisting a wet towel. This forces the head of the femur deep securely into the acetabular fossa.

Discuss the structure of the right ventricle of the heart, including muscles, innervation, vasculature, relationship to the pericardium, and function. Include a discussion of the the atrioventricular and semilunar valves. (12 pts)

General comments

• The right ventricle is "C" shaped relative to the more circular left ventricle. Wall thickness is about 1/3 that of the left ventricle. This reflects differences in the distribution of the pulmonary artery (lungs) and the aorta (entire body). The inner surface is lined by endocardium. The outer surface is lined by epicardium.
• makes anterior or sternocostal aspect of heart
• left posterior wall is made up of interventricular septum
• epicardium faces pericardial cavity and serous parietal pericardium adjacent to sternum and central tendon of diaphragm

Innervation, Interventricular Septum and Conduction - separates the right and left ventricles

• superficial and deep cardiac plexuses
• right coronary plexus supplies majority of right ventricle
• sympathetic - cardiac nerves, dilates coronary arteries, increases heart rate
• parasympathetic - vagus nerve, constricts coronary arteries, decreases heart rate
• AV node - AV bundle - right and left crus (Purkinje fibers) distribute to ventricles
• right crus within septomarginal trabecula

Conus arteriosus (infundibulum)

• smooth "neck of funnel" leading toward the pulmonary valve

Muscles

• trabeculae carneae
• septomarginal trabecula
• smooth infundibulum
• three papillary muscles
• membranous portion - superior near pulmonary trunk

Vasculature and Lymphatic Drainage

• Right coronary a., marginal a, anterior and posterior interventricular aa,
  • posterior 1/3 interventricular septum by right coronary and anterior 2/3 by left coronary
  • sinuatrial a.
• small cardiac v., anterior cardiac vv.
• anterior and posterior aspects of the interventricular septum are by the great and middle cardiac veins respectively
• lymphatic drainage of right ventricle is to brachiocephalic nodes (left ventricle drains to tracheobronchial nodes)

The valves of the heart direct blood flow in one direction

• fibroelastic cardiac skeleton
• Between the atria and the ventricles are the atrioventricular valves
• Between the ventricles and arterial trunks are the semilunar valves
• Healthy valves permit little to no back flow
• Integrated with the skeleton of the heart
• Located in the ventricles (atrioventricular valves) and at the base of the arterial trunks (semilunar valves)
• The atrioventricular valves and the semilunar valves are closed by pressure (they are not closed by muscular contraction applied to the cusps)
• IVC to rt atria to tricuspid to rt ventricle to pulmonary valve to pulmonary artery to lungs to pulmonary veins to left atria to biscupid (mitral) valve to left ventricle to aortic valve to systemic circulation to coronary arteries during diastole
• Atrioventricular valves close (lub) during systole whereas the semilunar valves close (dub) during diastole

Tricuspid valve (right atrioventricular valve)

• Between the right atria and the right ventricle
• Three cusps open into the right ventricle - anterior, posterior, and septal, prevent retrograde flow from ventricle to atrium
  • collagenous core covered by endocardium
• Three papillary muscles (extensions of trabeculae carne) - anterior, posterior, and septal
  • each papillary mm stabilizes more than one cusp
  • prevent eversion of valve cusps
  • Note - contraction of the papillary muscles, in the absence of ventricular contraction, open, not close, the atrioventricular valves
• chordae tendinae - cord like structures attaching the cusps to the papillary mm
  • fibrous collagenous
  • Cusps are stabilized by chordae tendeneae
  • Adjustments by the papillary muscles and chorda tendeneae provide support and prevent eversion of the cusps into the atria
  • chordae tendinae from the septal wall may not have visible papillary muscle attachments
• Synchronization of papillary muscles handled by conduction system
• Ventricular contraction raises pressure - blood pools on ventricular side of cusps causing the cusps to approximate each other and close the valve

Semilunar valve - pulmonary valve

• Located at base of pulmonary trunk
• distal to infundibulum
• Prevents reverse flow from the pulmonary trunk to the right ventricle during diastole
• Opened by blood flow during systole - cusps move toward aortic wall and block coronary ostia
• Three cusps - no papillary muscles or chorda tendeneae
  • fibrous core covered by endocardium
• Nodule - weighted fibrous thicking at the midline of the free edge of each cusp aids in approximating the cusps and closing the valve
• Sinus - space between the wall and each cusp
• Valve closed by pressure - blood pools in the aortic sinuses during diastole and aproximates the nodules
• Operation is the same as aortic valve except that there are not coronary cusps (no ostia in pulmonary trunk)

Trabeculae carnea - muscular ridges of the right ventricle

• septomarginal trabeculae - arising from the interventricular septum and extending to anterior papillary m., carries purkinje fibers

Discuss the structure (muscles, bones, fascia, innervation, articulations, and vertebral projections) and movements of the thoracic cage, the collateral circulation of the arterial supply and venous drainage, and the lymhatics of the thorax.

General Comments.

• The vasculature supply to the thoracic wall travels within the neurovascular plane defined superficially by the internal intercostal muscles and membrane (posterior) and deeply by the subcostal (posterior), innermost intercostal (intermediate), and transversus thoracis (anterior) muscles. The intercostal veins, arteries, and nerves are located inferior to the costal groove of the superior rib defining an intercostal space. From superior to inferior is vein, artery, nerve. Posterior, lateral, and anterior branches of the intercostal vessels and nerves leave the neurovascular plane to supply superficial regions of the thoracic wall. The lateral branches further divide into posterior and anterior branches whereas the anterior branches further divide into medial and lateral branches.

Collateral circulation and structure

• The bulk of the anterior vasculature has the subclavian arteries and brachiocephalic veins as the parent vessels whereas the bulk of the posterior vasculature has the descending aorta (first two intercostal spaces excepted) and azygous system as the parent vessels. The anterior and posterior vasculatures anastomose within the thoracic wall. Thus, the aortic arch can deliver blood directly to the descending aorta or indirectly to the descending aorta by way of the anterior vasculature (subclavian to internal thoracic to anterior intercostals to posterior intercostals to descending). See below.
• Borders
  • anterior - sternum (manubrium, body, xiphoid process), chondral cartilages
  • posterior - vertebral bodies
  • lateral - ribs proper
  • superior - thoracic inlets
  • inferior - thoracic outlet
• Vertebral projections
  • sternal notch - T3
  • sternal angle - T4
  • xiphisternal junction - T9
  • inferior extent of costal margin - L3
• Fascial layers at midaxillary line
  1. skin
  2. telasubcutanea
  3. external intercostal
  4. internal intercostal
  5. neurovascular plane (van)
  6. innermost intercostal
  7. endothoracic fascia
  8. fibrous layer parietal costopleura
  9. serous layer of parietal costopleura
• Intercostal muscles - superficial to deep
  • External intercostals - anterior membrane, downward "V"
  • Internal intercostals - posterior membrane upward "V", superficial to neurovascular plane
  • Innermost intercostals - posterior as subcostals, anterior as transversus thoracis, deep to neurovascular plane
• Innervations
  • Motor innervations by intercostal nerves and posterior rami of spinal nerves T1-11
  • Cutaneous innervation described above in General Comments
    • Skin overlying xyphiod process is by spinal nerve T8
  • Autonomic innervation follows intercostal nerves
    • preganglionic cell bodies in IMLCC T1-11, postganglion cell bodies in thoracic sympathetic trunk ganglia
• Arteries
  • Posterior intercostal spaces
    • 1-2 Supereme (highest) thoracic artery from costocervical trunk of subclavian artery
    • 3-11 Posterior intercostal arteries from the descending aorta
  • Anterior intercostal spaces
    • 1-6 - Internal thoracic artery from subclavian artery
    • 7-9 - Musculophrenic artery from internal thoracic artery
    • 10-11 - Superior epigastric from internal thoracic artery
• Veins
  • Right posterior intercostal spaces
    • 1 - Supreme (highest) intercostal vein from brachiocephalic vein
    • 2-4 - superior intercostal vein from arch of the azygous vein
    • 5-11 - Posterior intercostal veins from azygous vein
  • Left posterior intercostal spaces
    • 1 - Supreme (highest) intercostal vein from brachiocephalic vein
    • 2-4 - superior intercostal vein from accessory hemiazygous vein, or brachiocephalic vein, or coronary sinus
    • 5-11 - Posterior intercostal veins from hemiazygous vein
  • Anterior intercostal spaces
    • 1-6 - Internal thoracic vein
    • 7-9 - Musculophrenic vein
    • 10-11 - Superior epigastric vein

Ribs, Movements and Breathing

• Ribs
  • True ribs
  • False ribs
  • Floating ribs
• Joints
  • costovertebral
  • costotransverse
  • costochondral
  • sternochondral
• Anterior posterior - pump handle and costotransverse joint
  • cupped tubercle of transverse process results in pump handle of upper ribs
  • costochondral and sternochondral joints involved
  • The pump-handle movement of respiration refers to the movements of the upper 6 ribs during breathing. During inspiration there is an increase in the anterior-posterior diameter of the thorax. The sternum moves superiorly and anteriorly in accord with rib movements occurring at the costovertebral, costotransverse, costochondral, and sternochondral joints. Relative to the lower ribs, the costotransverse joint articulation at the transverse process is cupped and accommodates the tubercle of the rib. This articulation permits the rib to rotate on a transverse axis. A slight downward movement at the head of the rib is amplified distally at the sternum. This movement is transferred to the sternum by the costochondral and sternochondral joints. The result is that the sternum raises on inspiration much like the raising of a pump-handle when drawing water from the depths of a well
• transverse - bucket handle and costotransverse joint
  • planar tubercle of transverse process permits an outward sliding of the rib and results in bucket handle of lower ribs
  • costochondral and sternochondral joints involved
• vertical - diaphragmatic
  • phrenic n., pericardiacophrenic vessels, ant. post. intercostal vessels
  • Upon diaphragmatic contraction the height of the diaphragmatic dome drops to increase the vertical extent of the thoracic cavity.
• capillary effect, negative pressure, etc.
  • pneumothorax - air enters and breaks capillary effect, loss of negative pressure, the lung collapses

Lymphatic Drainage

• Laterally, lymph drainage from the anterior thoracic wall (breast) is into groups of axillary nodes. Most of this drainage is into the pectoral nodes located along pectoral branches of the thoracoacromial vessels. Pectoral nodes drain into the apical nodes located near the apex of the axilla. On the left, the axillary nodes give rise to the subclavian lymphatic trunk. This vessel commonly drains into the thoracic duct and then the angle of internal jugular. The right subclavian duct often drains directly into the venous system. Apical nodes also have drainages into cervical and supraclavicular nodes. Metastatic disease in these nodes is especially difficult to remove.
• The medial aspect of the breast is drained by intercostal vessels into parasternal nodes. Parasternal and paratracheal drainages combine to form the bronchomediastinal lymph trunks. Drainage continues into the right lymphatic duct on the right and the thoracic duct on the left.
• The breast is also drained by subcutaneous vessels. These vessels have a wide distribution ranging from the cervical region to the inguinal region and crossing the midline. If the deeper lymph channels are blocked, as may be the case with cancer, subcutaneous drainage may greatly increase and widely disperse cancerous cells.
• axillary notes receive 75% of lymphatic drainage
  • pectoral nodes - lateral border of pectoralis major
  • apical nodes - beneath the clavicle
  • supraclavicular nodes
  • cervical nodes
• parasternal nodes
  • along the internal thoracic artery
• subcutaneous lymphatics
  • distribute to wide area if deep lymphatics are blocked (e.g. cancer)
• intercostal nodes
  • along the azygous veins in the posterior mediastinum
  • drain posterior intercostal spaces
  • left intercostal nodes may drain directly into thoracic duct
  • right intercostal nodes may find their way to the right lymphatic duct
• left/right differences
  • right side into right (subclavian) lymph duct
  • left side into thoracic duct and left subclavian v.
• Summary.
  • Laterally, lymph drainage from the breast is into groups of axillary nodes. Most of this drainage is into the pectoral nodes located along pectoral branches of the thoracoacromial vessels. Pectoral nodes drain into the apical nodes located near the apex of the axilla. On the left, the axillary nodes give rise to the subclavian lymphatic trunk. This vessel commonly drains into the thoracic duct and then the angle of internal jugular. The right subclavian duct often drains directly into the venous system. Apical nodes also have drainages into cervical and supraclavicular nodes. Metastatic disease in these nodes is especially difficult to remove.
• The medial aspect of the breast is drained by intercostal vessels into parasternal nodes. Parasternal and paratracheal drainages combine to form the bronchomediastinal lymph trunks. Drainage continues into the right lymphatic duct on the right and the thoracic duct on the left.
• The breast is also drained by subcutaneous vessels. These vessels have a wide distribution ranging from the cervical region to the inguinal region and crossing the midline. If the deeper lymph channels are blocked, as may be the case with cancer, subcutaneous drainage may greatly increase and widely disperse cancerous cells.
• Posterior intercostal spaces drain into intercostal nodes located in the posterior mediastinum.

Discuss the anatomy of the hip joint. Include an account of the innervation, vascular supply, muscles, ligaments, bones and articulations, movements and limitations of movements, and stability. (12 pts)

General comments

• This hip joint is a synovial "ball and socket" joint

Bones and articulations

• head of femur (ball fits into the acetabulum (socket)
• depth of acetabulum is increased by labrum, labrum overlies the transverse acetabulum ligament at the acetabular notch
  • labrum is non-interrupted
• acetabular notch bridged by the transverse acetabular lig *creates a foramen - posterior branch obturator artery
• articular cartilage on head of femur and on lunate surface of acetabular fossa
• ligamentum teres attaches to acetabular fossa near transverse acetabular ligament
  • Intracapsular and extrasynovial
• synovial reflections and extensions/bursae

Ligaments - capsular thickenings

• pubofemoral - from pectin line to intertrochanteric line, resists abduction
• iliofemoral - from anterior inferior iliac spine (deep to rectus femoris straight head) to intertrochanteric line and lessor trochanter (Y-ligament)
  • fibers spiral from superior anterior medial to inferior posterior lateral - resist extension and shorten on extension to stabilize joint through a "screw home" mechanism that, in turn, leads to close packing of the joint.
• ischiofemoral - from ischium to greater trochanter and intertrochanteric line, resists hyperextension and flexion

Movements, limitation of movement, innervations, and muscle stabilization

• flexion
  • psoas major - lumbar plexus
  • anterior compartment of thigh - femoral nerve
    • rectus femoris - long head
    • sartorius (lateral rotation)
    • tensor fascia lata
  • limited by trunk and hamstrings
• extension
  • posterior compartment of thigh (hamstrings and posterior adductor magnus) - tibial portion of sciatic
  • gluteus maximus - inferior gluteal nerve
  • limited by ligaments of joint capsule (see above)
• adduction
  • medial compartment of thigh and obturator externus - obturator nerve
  • limited by opposite thigh and ligament to the head of the femur
• abduction
  • gluteus minimus and medius and tensor facia lata - superior gluteal nerve
  • limited by pubofemoral ligament and adductors
• lateral rotation
  • short rotators of gluteal region - lumbosacral plexus
  • long head of the biceps - tibial portion of sciatic
  • sartorius - femoral nerve
  • relatively free - limited by neck of femur and pubofemoral ligament
• medial rotation
  • anterior part of gluteus minimus (medius) - superior gluteal nerve
  • gracilis - obturator
  • semitendonosus and semimembranosus - tibial portion sciatic
  • limited by joint capsule
• Muscles - all muscles that cross the joint contribute to stabilization
  • anterior group - flexors: iliopsoas adds major support, rectus femoris, sartorius
  • medial group - all of the adductors
  • posterior group - extensors: the hamstrings
  • gluteal region - rotators and abductors: the five short lateral rotators, gluteus maximus, medius, and minimus, tensor fascia lata
  • fascial specialization - iliotibial tract

Stability

• • The hip joint is maximally stable during extension as is the case during quiet standing. The line of gravity falls behind the axis causing to hip to extend. Capsular thickenings (aforementioned ligaments) spiral from posterior to anterior and from medial on the pelvic girdle to lateral on the femur. As the ligaments tighten the capsule shortens similar to twisting a wet towel. This forces the head of the femur deep securely into the acetabular fossa.

Vascularization

• Cruciate anastomosis - Arteries and key relationships

Innervation

• Hilton's law - all nerves that cross the joint provide innervation to the joint tissues.
  • • Obturator, femoral, and sciatic, and the superior and inferior gluteal nerves

A nail penetrates the medial sole of the foot and pierces the spring ligament. Discuss the fascia, muscles, tendons, nerves (including cutaneous innervation), bones,, and vasculature involved with this injury. Discuss the repercussions on the medial longitudinal arch and on gait. (12 pts)

Explicit Statement of Penetrated Structures

1. Skin and plantar aponeurosis
2. Lateral border of abductor hallucis
3. Medial plantar a. and v.
   • The lateral plantar a.v. is posterio-lateral to site of penetration and is spared
   • Deep plantar arch is distal to site of penetration and is spared
4. Medial border of flexor digitorum brevis
5. Tendons of flexor digitorum longus
   • near or immediately distal to crossing of tendons
   • lateral border of tibialis posterior tendon might be damaged
6. Medial border of quadratus plantae
7. Tendon of flexor hallucis longus
8. Spring ligament
9. Head of talus within floor of talocalcaneonavicular joint

Medial Longitudinal Arch

• Bones
  • calcaneus, head of talus, navicular, cuneiforms, and first 3 metatarsals (heads of) - labeled drawing was helpful (with discussion)
  • talocalcaneonavicular joint has the head of the talus of as the "keystone" wedged between the calcaneus and navicular
  • spring ligament is the floor of the talocalcaneonavicular joint and acts as a "staple" to approxmate the navicular to the calcaneus
• Ligaments
  • Spring ligament - plantar calcaneonavicular ligament
    • maintains the head of talus at the peak of the medial longitudinal arch
    • stretching of this ligament allows the navicular bone to move away from the calcaneus; if stretched, the talus falls
  • minor support by long and short plantar
• Muscles
  • Suspends the arch
    • tibialis posterior - suspends the arch
    • tibialis anterior - suspends the arch
    • extensor hallucis longus - suspends the arch
  • Staples the arch
    • peroneus longus - tendinous insertions staple the arch
      • note: peroneus longus is a tie beam for the transverse arch, a vertical support for the lateral longitudinal arch, and a staple for the medial longitudinal arch
    • tibialis posterior - tendinous insertions staple the arch
    • tibialis anterior - tendinous insertions staple the arch
  • "Tie beam" support - structures serving to approximate the bones of the arch
    • intrinsic mm - adductor hallucis oblique head, flexor hallucis, abductor hallucis, flexor digitorum brevis, quadratus plantae, lumbricals
    • extrinsic mm - flexor hallucis longus is key, tibialis posterior, flexor digitorum longus
    • fascia - plantar aponeurosis and septa
    • skin
• Fascial Specializations
  • fascia - plantar aponeurosis and septa
  • skin
• Neural and Vascular Relationships
  • Tibial nerve and posterior tibial artery elaborate medial and lateral plantar arteries and nerves
  • Medial and lateral plantar nerves and vessels pass deep to abductor hallucis to enter plantar region
  • Lateral planter nerve and vessels pass superior to flexor hallucis brevis and inferior to quadratus plantae to reach lateral aspect of sole.
• Consequences of Damage
  • A fallen medial arch indicates failure of the spring ligament to approximate the navicular bone to the calcaneus. As a result, the head of the talus moves inferiorly into the region traversed by the medial and lateral plantar vessels and nerves. Compression of these structures could lead to cold feet (poor circulation) and paraesthesias (compressed nerves).

Discuss the anatomy of the popliteal fossa, and include an account the boundaries, structures entering and leaving at each boundary, vascular supply, innervation, ligaments, bones, contents, lymphatics, muscles, and relationships. (12 pts)

General comments

• Posterior to knee, diamond shaped, fat filled, passage of key structures to the lower limb

Boundaries, bones, ligaments, crossing structures, vasculature

• Superior boundary - apex of diamond formed by semimembranosus and semitendinosus diverging from biceps femoris
  • sciatic n. - enters from posterior thigh deep to hamstrings, divides into tibial (medial) and common peroneal (lateral) nn.
• Superior lateral boundary - biceps femoris
  • superior lateral genicular a.v. - leaves popliteal fossa femur at lateral femoral epicondyle superior to origin of gastrocnemius and deep to biceps femoris
• Superior medial boundary - semitendinosus and semimembranosus
  • superior medial genicular a.v. - leaves popliteal fossa at medial femoral epicondyle superior to adductor tubercle and deep to semimembranosus
• Inferior lateral boundary - lateral head of gastrocnemius
  • inferior lateral genicular a.v. - leaves popliteal fossa crossing posterior surface of popliteus fascia and arcuate ligament, deep to head of gastrocnemius
  • common peroneal n. - leaves popliteal posterior to lateral head gastrocnemius and lateral to neck of fibula
• Inferior medial boundary - medial head of gastrocnemius
  • inferior medial genicular a.v. - leaves popliteal fossa posterior surface of tibia near the plateau, deep to head of gastrocnemius
• Inferior boundary - apex of diamond formed by convergence of the two heads of gastrocnemius
  • posterior tibial a.v. - leaves popliteal fossa deep to the heads of origin of soleus
  • sural aa. - leaves popliteal fossa by entering the bellies of gastrocnemius
  • branches of tibial n. to the gastrocnemius
• Posterior boundary - popliteal fascia (deep fascia), tranisition from fascia lata to crural fascia
  • medial and lateral sural nn. - branches for tibial and common peroneal nn.
  • short saphenous v. - pierces popliteal fascia to enter the popliteal v.
• Anterior boundary - femur, tibial plateau, joint capsule, oblique popliteal lig., arcuate lig., popliteus m.
  • popliteal a.v. - enter through adductor hiatus (superior medial anterior in the fossa) as continuation of the femoral vessels; artery deep to vein.
  • middle genicular a. leaves popliteal fossa through the posterior aspect of the joint capsule

Innervation

• branches of the sciatic, tibial, and common peroneal provide sensory innervation to the region
• posterior femoral cutaneous nerve provides cutaneous innervation
• femoral and obturator nerves may, in part, supply the anterior reaches

Key Relations within the fossa

• superficial to deep: sciatic n and branches, femoral v., femoral a.
• arteries of genicular anastomosis applied to capsule and bone

Lymphatic drainage - popliteal lymph nodes

• superficial drainage of leg enters popliteal fossa along with the lesser saphenous v.
• deep drainage of leg enters popliteal fossa along with posterior tibial vessels
• lymph from popliteal fossa ascend along femoral vessels to deep inquinal nodes

Define the posterior mediastinum and discuss contents (nerves, viscera, lymphatics, vasculature), relationships and boundaries. (12pts)

Definition and Boundaries

• superior - line from T4 toward jugular notch (only that part of line posterior to middle mediastinum)
• inferior - diaphragm posterior to middle mediastinum; T12
• lateral - fibrous layer of mediastinal parietal pleura
• anterior - posterior to middle mediastinum
• posterior - lateral aspects of vertebral bodies (includes sympathetic trunk)
• medial - the middle of the posterior mediastinum is also midsaggital, i.e., a medial boundary does not exist

Innervation

• deep cardiac plexus
• esophageal plexus (right and left vagus)
• ventral rami of thoracic spinal nerves (intercostals nerves)
• Sympathetic truck and related structures

Arteries

• right posterior intercostal arteries
• esophageal arteries
• bronchial arteries
• aorta

Veins

• azygos system of veins
• arch of the azygos (subject to interpretation)
• right superior intercostal vein (subject to interpretation)
• right posterior intercostal veins

Lymph

• thoracic duct

Viscera

• bifurcation of trachea (Subject to interpretation)
• esophagus

Relationships

• right posterior intercostal aa. - immediately deep to azygos system and sympathetic trunk
• azygos system - azygos v. and hemiazygos v., cross anterior vertebral bodies superficial to right intercostal aa and deep to splanchnic nn.
• thoracic sympathetic trunk - immediately superficial (lateral) to intercostal vessels
• splanchnic nerves - coursing inferior medial and anterior from sympathetic trunk ganglia
• ramus communican - branching posterior from sympathetic trunk ganglia and connecting to spinal nerve at intervertebral foramen
• thoracic duct - superficial to azygos v. between esophagus and aorta, deviates to the left in superior region
• esophagus and esophageal plexus - deviates to the right superiorly and left inferiorly; site of constrictions
• aorta - left of vertebral bodies and esophagus
• vagus n. - enters posterior to root of lung
• bifurcation of trachea - immediately anterior to esophagus in superior region of posterior mediastinum
• deep cardiac plexus and nerves - anterior to tracheal bifurcation

Discuss the medial longitudinal arch and indicate your understanding of the bones, ligaments, muscles, and fascial specialization, and relate your anatomical knowledge to the consequences of damage to these structures. (12 pts)

Bones

• calcaneus, head of talus, navicular, cuneiforms, and first 3 metatarsals (heads of) - labeled drawing was helpful (with discussion)
• talocalcaneonavicular joint has the head of the talus of as the "keystone" wedged between the calcaneus and navicular
• spring ligament is the floor of the talocalcaneonavicular joint and acts as a "staple" to approxmate the navicular to the calcaneus

Ligaments

• Spring ligament - plantar calcaneonavicular ligament
  • maintains the head of talus at the peak of the medial longitudinal arch
  • stretching of this ligament allows the navicular bone to move away from the calcaneus; if stretched, the talus falls
• minor support by long and short plantar

Muscles

* Suspends the arch

• • tibialis posterior - suspends the arch
  • tibialis anterior - suspends the arch
  • extensor hallucis longus - suspends the arch
• Staples the arch
  • peroneus longus - tendinous insertions staple the arch
    • note: peroneus longus is a tie beam for the transverse arch, a vertical support for the lateral longitudinal arch, and a staple for the medial longitudinal arch
  • tibialis posterior - tendinous insertions staple the arch
  • tibialis anterior - tendinous insertions staple the arch
• "Tie beam" support - structures serving to approximate the bones of the arch
  • intrinsic mm - adductor hallucis oblique head, flexor hallucis, abductor hallucis, flexor digitorum brevis, quadratus plantae, lumbricals
  • extrinsic mm - flexor hallucis longus is key, tibialis posterior, flexor digitorum longus
  • fascia - plantar aponeurosis and skin

Fascial Specializations

• fascia - plantar aponeurosis and skin; tie beam
• skin

Neural and Vascular Relationships

• Tibial nerve and posterior tibial artery elaborate medial and lateral plantar arteries and nerves
• Medial and lateral plantar nerves and vessels pass deep to abductor hallucis to enter plantar region
• Lateral planter nerve and vessels pass superior to flexor hallucis brevis and inferior to quadratus plantae to reach lateral aspect of sole.

Consequences of Damage

• A fallen medial arch indicates failure of the spring ligament to approximate the navicular bone to the calcaneus. As a result, the head of the talus moves inferiorly into the region traversed by the medial and lateral plantar vessels and nerves. Compression of these structures could lead to cold feet (poor circulation) and paraesthesias (compressed nerves).

Discuss the structure and function (including blood flow to the coronary vessels) of the semilunar valves and the atrioventricular valves (12 pts)

The valves of the heart direct blood flow in one direction

• Between the atria and the ventricles are the atrioventricular valves
• Between the ventricles and arterial trunks are the semilunar valves
• Healthy valves permit little to no back flow
• Integrated with the skeleton of the heart
• Located in the ventricles (atrioventricular valves) and at the base of the arterial trunks (semilunar valves)
• The atrioventricular valves and the semilunar valves are closed by pressure (they are not closed by muscular contraction applied to the cusps)
• IVC to rt atria to tricuspid to rt ventricle to pulmonary valve to pulmonary artery to lungs to pulmonary veins to left atria to biscupid (mitral) valve to left ventricle to aortic valve to systemic circulation to coronary arteries during diastole
• Atrioventricular valves close (lub) during systole whereas the semilunar valves close (dub) during diastole

Atrioventricular valve - Tricuspid

• Between the right atria and the right ventricle
• Three cusps open into the right ventricle
• Three papillary muscles (extensions of trabeculae carne) - anterior, posterior, and septal
• Synchronization of papillary muscles handled by conduction system
• Cusps are stabilized by chorda tendeneae - fibrous cords between cusps and papillary muscles
• Ventricular contraction raises pressure - blood pools on ventricular side of cusps causing the cusps to approximate each other and close the valve
• Adjustments by the papillary muscles and chorda tendeneae provide support and prevent eversion of the cusps into the atria
• Note - contraction of the papillary muscles, in the absence of ventricular contraction, open, not close, the atrioventricular valves

Atrioventricular valve - Biscuspid (Mitral Valve)

• Between the left atria and the left ventricle
• Two cusps open into the left ventricle
• Two papillary muscles - anterior and posterior
• Resists extreme pressure generated by left ventricular contraction

Semilunar valve - aortic valve

• Located at the base of the aortic trunk
• Prevents reverse flow from the aorta to the left ventricle during diastole
• Negative pressure of left ventricle and elastic recoil of systemic arteries move aortic blood toward the valve
• Opened by blood flow during systole - cusps move toward aortic wall and block coronary ostia
• Three cusps - no papillary muscles or chorda tendeneae
• Left and right coronary cusps and a non-coronary cusp
• Nodule - weighted fibrous thicking at the midline of the free edge of each cusp aids in approximating the cusps and closing the valve
• Aortic sinus - space between the wall of the aorta and each cusp
• Valve closed by pressure - blood pools in the aortic sinuses during diastole and aproximates the nodules

Semilunar valve - pulmonary valve

• Located at base of pulmonary trunk
• Prevents reverse flow from the pulmonary trunk to the right ventricle during diastole
• Operation is the same as aortic valve except that there are not coronary cusps (no ostia in pulmonary trunk)

Blood flow to the coronary vessels

• Coronary arteries are perfused during diastole when heart muscle is relaxed
• During systole the coronary ostia are blocked by the open cusps of the aortic valve
• During diastole blood pools in the aortic sinuses and closes the aortic valve.
• Blood driven into the left and right aortic sinuses enters into the ostia of the coronary arteries.

Review the anatomy of the knee joint and include bones, articulations, ligaments, cavities and bursa, vasculature, muscles, fascial specializations, and stability of the joint. Explain the tenderness on the medial side of the knee, and the abnormal forward movement of the tibia in relationship to the femur. (12 pts)

Bones and Articulations

• Synovial hinge joint between the femoral and tibial condyles.
• Tibial plateau is cupped by the medial and lateral menisci.
• Femoral condyles - shape
• Tibial condyles - shape
• Patella articulates anteriorly as a sesamoid bone in the quadriceps tendon.
• Articular cartilage

Ligaments

• Medial collateral ligament (attached to medial meniscus).
  • medial femoral epicondyle to the medial tibial condyle.
  • resists abduction of tibia
• Lateral collateral ligament (interval between lateral meniscus and ligament transmits popliteus tendon
  • From lateral femoral epicondyle to the head of the fibula
  • resists adduction of tibia
• Anterior cruciate ligament
  • from lateral posterior femoral condyle to anterior aspect of tibial intercondyler eminence.
  • resists forward displacement of the tibia.
  • Alar fold
• Posterior cruciate ligament
  • from posterior medial femoral condyle to posterior aspect of tibial intercondyler eminence.
  • resists posterior displacement of tibia
  • Alar fold
• Oblique popliteal and arcuate ligaments strengthen the posterior joint capsule.
  • Semibranosus
  • Popliteus
• Coronary, transverse genicular, and meniscofemoral ligaments secure the menisci.
  • Tibial plateau

Cavities and bursae

• Synovial joint cavity
  • attaches to edges of menisci - articular surface is intrasynovial
  • Alar folds anterior to anterior crucial ligament - posterior limit of midsaggital synovial cavity
  • reflections of the synovial membrane along the intercondylar fossa - cruciate ligaments are extrasynovial.
  • continuous with suprapatellar bursa (quadriceps bursa)
    • Articularis genu
• prepatellar bursa
  • bursitis
• infrapatellar bursa
  • Superficial and deep
• Joint Capsule
  • ligaments making up the capsule (above)
  • intercondylar area is extrasynovial
  • popliteus tendon within cavity
  • patellar retinaculum
  • patellar and quadraceps tendon

Muscles, Movements and limitations of movement

• Primarily flexion and extension (hinge joint).
• Some rotation (30-40 degrees) is possible when the knee is flexed
• Flexion is primarily by the hamstrings, short head of biceps, gracilis, and sartorius.
  • innervated by tibial portion sciatic, peroneal portion sciatic, obturator, and femoral nerves respectively.
  • minor flexion by popliteus, gastrocnemius, and plantaris.
  • flexion is limited by quadriceps, cruciate ligaments, and by opposing soft tissues (calf and thigh).
• Extension is primarily by the quadriceps and tensor fascia lata.
  • innervation by femoral nerve and superior gluteal nerve.
  • extension is limited by hamstrings, cruciate ligaments, collateral ligaments, posterior joint capsule.
• Medial rotation of tibia is primarily by popliteus, semitendonosus, gracilis, and sartorius.
  • innervation by tibial nerve, tibial portion sciatic, obturator, and femoral nerves respectively.
  • limitation of movement by collateral ligaments
• Lateral rotation of tibia is primarily by biceps femoris.
  • innervation by tibial and peroneal portions of sciatic nerve.
• limitation of movements by collateral ligaments.
  • Abduction and adduction is limited by the medial and lateral collateral ligaments.
• Fascial Specializatons
  • patellar retinaculum
  • iliotibial tract
  • investing fascia
• vascular supply
  • Genicular anastomosis
    • Superior and inferior, medial and lateral genicular arteries, and middle genicular from the popliteal artery.
      • Middle genicular artery and intercondylar space
    • Descending genicular artery from femoral artery and descending branch from lateral femoral circumflex artery.
    • Fibular circumflex artery, and anterior and posterior tibial recurrent arteries from the anterior and posterior tibial artery
    • Accompanying veins
• Innervation (Hilton's Law)
  • small branches of the femoral, obturator, and sciatic, and tibial nerves pierce the joint capsule.
• "Screw Home"
  • Consider when the knee is extended with the foot planted on the ground. In this case, the tibia is fixed by virtue of the planted foot. Thus, rotation of the knee occurs as movement of the femur. The femur rotates medially as the knee "locks" in extension. The lateral femoral condyle is smaller than the medial femoral condyle. As the knee is extended the smaller condyle moves through its arc before the medial condyle. Thus, movement stops at the lateral condyle while the femoral medial condyle continues to move further posteriorly. This movement results in a medial rotation of the femur.
  • This medial rotation torques the joint capsule and it's ligamentus specializations (medial and later collateral ligs). The "twisting" of the capsular ligaments causes the region to tighten. This firmly approximates the femoral condyles to the tibial plateau and "locks" the knee. The femur "screws" medially onto the tibial plateau due to the larger medial condyle and the twisting of the capsular ligaments. On extension, the knee goes through a "screw home" rotation that results in "close packing."
  • The final medial rotation of the femur is driven by the line of gravity moving anterior to the axis of the knee joint. Thus, locking the knee is driven by gravity. Unlocking the knee requires muscular involvement. The popliteus, having lateral superior to medial inferior attachments, posterior to the axis of the knee, can to lateral rotate the femur (reverse origin and insertion) and, thus, unlock the knee joint.

Review the boundaries (6 in number) and contents (vasculature, nerves, lymphatics) of the femoral triangle. State the relationship of structures entering and leaving this region. (12 pts)

Superior boundary: Inguinal ligament spanning the anterior superior iliac spine and pubic tubercle (including a figure would help)

• contents of the muscular and vascular lacunae enter the femoral triangle (discuss relations)
• Vascular lacuna.
  • The vascular lacuna is located posterior to the inguinal ligament, medial to the iliopectineal arch, lateral to the lacunar ligament, and anterior to the pectineal fascia.
  • The contents include, from the lateral to medial, the femoral artery, the femoral vein, and the femoral canal.
  • These contents are contained within compartments of the femoral sheath. These compartments are separated by septa that run between the inguinal ligament and the pectineal fascia.
  • Femoral hernias occur in this region.
  • abdominal viscera may enter the femoral canal through the femoral ring.
• Muscular lacuna
  • posterior to inguinal ligament and lateral to iliopectineal arch
  • femoral nerve enters femoral triangle deep to iliacus fascia
  • lateral femoral cutaneous nerve enters femoral triangle lateral to femoral nerve and near anterior superior iliac spine

Lateral boundary: sartious

• lateral femoral circumflex a/v exits laterally deep to sartious and between rectus femoris and vasti

medial boundary: adductor longus

• profunda femoral a/v exits posteromedial deep to super border of adductor longus and continues between adductor longus and adductor magnus

Inferior boundary: adductor canal at the apex

• Adductor canal.
• At the apex of the femoral triangle is the beginning of the adductor canal.
• The femoral artery and vein, and the saphenous nerve enter the adductor canal.
• The femoral artery is anterior to vein - note: this relation betrays relation of popliteal vessels
• The adductor canal is bounded anteromedially by the sartorius muscle. Anterolaterally, it is bounded by the vastus medialis. Posteriorly it is bounded by adductor longus and adductor magnus.
• nerve to vastus intermedius enters adductor canal
• deep lymphatics ascend adductor canal to femoral triangle

Posterior boundary: iliopsoas, pectineus, and possibly parts of adductor brevis and adductor longus

• the medial femoral circumflex a/v exits between iliopsoas and pectineus
• the deep femoral artery exits between iliopsoas and adductor longus

Anterior boundary: fascia lata and saphenous hiatus (show relations fig)

• the contents of the cribriform fascia exit the femoral triangle at this location
• superficial/external pudendal a/v
• superficial epigastric a/v
• superficial circumflex iliac a/v
• the great saphenous vein
• anterior femoral cutaneous nn pierce fascia lata anterior.

Further discussion

• The saphenous hiatus
  • is a specialization of the fascia lata located in the anteromedial thigh just inferior to the inguinal ligament and superficial to the femoral sheath. The lateral margin overlies the femoral artery. The medial aspect overlies the femoral canal. Superiorly is the inguinal ligament. Approximately 2cm inferior to the inguinal ligament is the inferior cornu over which the great saphenous vein forms an arch as it leaves superficial fascia and enters the femoral vein. Notable tributaries of the great saphenous vein within the saphenous hiatus are the external pudendal vein coursing medially, the superficial epigastric vein coursing superiorly, and the superficial circumflex iliac vein coursing laterally and superiorly. Accompanying these veins are branches of the femoral artery. These vessels are piercing through the surrounding cribriform fascia. The distinct lateral margin of the saphenous hiatus is the falciform edge. There are superior and inferior borders referred to as the superior and inferior cornu. Medially, the hiatus is indistinct and blends with the pectineus fascia. The femoral ring is located immediately deep to the medial aspect of the saphenous hiatus. A femoral hernia, if present, can be palpated at this location. Additionally, a femoral pulse can be located and, thus, easy surgical access to a major artery or vein is possible.
• Femoral canal
  • Lymph funnel shaped lymph channel located in the most medial compartment of the femoral sheath.
  • Femoral ring is at the superior opening of this canal.
  • Formed by an 1.5cm extension of transversalis fascia from the abdominal cavity into the thigh.
  • Exposed to superficial fascia by the saphenous hiatus.
  • Site of femoral hernia
  • more common in females because of wider pelvic bones and larger femoral ring.

Discuss the boundaries, contents, and relationships in the anterior compartment of leg; include muscles, nerves, vasculature, and fascial specializations. Indicate the function of the anterior compartment of the leg, and define the effects of injury to this comparatment on the actions and sensitivity of the foot. Explain the weak pulse of the dorsalis pedis artery in the case of compartment syndrome. Using your anatomical knowledge, what can you recommend for treatment? (12 pts)

General

• The anterior compartment of the leg is responsible for extension of the toes, dorsiflexion at the talocrual joint, and inversion/eversion at the subtalar joints.

Fascial specializations

• crual fascia - investing fascia making up the anterior boundary of the anterior compartment
• Anterior intermuscular septum attaches to fibula - separates the anterior from the lateral compartment
• Interosseous membrane - separates the anterior from the posterior compartment
• Extensor retinaculum supports redirection of extensor tendons, tendon sheaths

Boundaries

• Superior - crual fascia knee joint capsule
• Inferior - continuous with dorsum of foot
• Anterior - crual fascia
• Posterior - interosseous membrane
• Lateral - anterior intermuscular septum and fibula
• Medial - lateral contour of tibia

contents and relationships

• Muscles - from medial to lateral
  • tibialis Anterior - origin from tibia and insertion on plantar side of 1st cuneiform and navicular
    • dorsiflexion of talocrural joint and inversion of subtalar joints
  • extensor hallucis longus - origin from tibia/interosseous membrane to extensor hood of great toe
    • extends the great toe, dorsiflexes the talocrural joint, inversion of subtalar joints
  • extensor digitorum longus- origin from fibula/interosseous membrane to extensor hood of toes 2-5
    • extends toes 2-5, dorsiflexes talocrural joint
  • peroneus tertius - origin from lower third of fibula to base of fifth metatarsal
    • eversion of subtalar joints, dorsiflexion of talocrural joint
• Nerves
  • Deep peroneal nerve - pierces posterior and anterior intermuscular septa (crual fascia)
    • crosses lateral aspect of the neck of the fibula prior to entering anterior compartment
    • pierces posterior and anterior intermuscular septa
    • applies to anterior surface of interosseous membrane and deep to extensor hallucis longus
    • runs along lateral aspect of anterior tibial artery
    • supplies cutaneous innervation to space between toes 1 and 2
• Vasculature
  • anterior tibial artery - from posterior tibial artery within posterior compartment, enters anterior compartment at superior free edge of interosseous membrane
  • fibular circumflex artery - superior in compartment
  • peroneal artery (posterior compartment) - inferior, branches pierce interosseous membrane
  • branches of the malleolar anastomosis

Support of the arches of the foot

• tibialis anterior supports the medial longitudinal arch as "suspension" element
• Peroneus tertius supports the lateral longitudinal arch as "suspension" element

Injury

• Damage to the anterior compartment would cause the foot drop due to unopposed flexors of the talocrural joint (posterior compartment). The medial and lateral longitudinal arches are weaken. The pulse at the dorsalis pedis is weakened due to compression within the anterior compartment. Paraesthesia is expected between the first and second toes. Decompression might require cutting the crural fascia.

Review the anatomy of the knee joint and include bones, articulations, ligaments, cavities and bursa, vasculature, muscles, fascial specializations, and stability of the joint. Explain the tenderness on the medial side of the knee, and the abnormal forward movement of the tibia in relationship to the femur. (12 pts)

Bones and Articulations

• Synovial hinge joint between the femoral and tibial condyles.
• Tibial plateau is cupped by the medial and lateral menisci.
• Femoral condyles
• Patella articulates anteriorly as a sesamoid bone in the quadriceps tendon.

ligaments

• Medial collateral ligament (attached to medial meniscus).
  • medial femoral epicondyle to the medial tibial condyle.
  • resists abduction of tibia.
• Lateral collateral ligament (interval between lateral meniscus and ligament transmits popliteus m.
  • From lateral femoral epicondyle to the head of the fibula
  • resists adduction of tibia.
• Anterior cruciate ligament
  • from lateral posterior femoral condyle to anterior aspect of tibial intercondyler eminence.
  • resists forward displacement of the tibia.
• Posterior cruciate ligament.
  • from posterior medial femoral condyle to posterior aspect of tibial intercondyler eminence.
  • resists posterior displacement of tibia.
• Oblique popliteal and arcuate ligaments strengthen the posterior joint capsule.
• coronary, transverse genicular, and meniscofemoral ligaments secure the menisci.

Cavities and bursae

• Synovial joint cavity
  • attaches to edges of menisci - articular surface is intrasynovial
  • Alar folds anterior to anterior crucial ligament - posterior limit of midsaggital synovial cavity
  • reflections of the synovial membrane along the intercondylar fossa - cruciate ligaments are extrasynovial.
  • continuous with suprapatellar bursa (quadriceps bursa)
• prepatellar bursa
• infrapatellar bursa

Capsular joint cavity

• ligaments making up the capsule (above)
• intercondylar area is extrasynovial
• popliteus tendon within cavity

Muscles, movements and limitations of movement

• Primarily flexion and extension (hinge joint).
• Some rotation (30-40 degrees) is possible when the knee is flexed.
• Flexion is primarily by the hamstrings, short head of biceps, gracilis, and sartorius.
  • innervated by tibial portion sciatic, peroneal portion sciatic, obturator, and femoral nerves respectively.
  • minor flexion by popliteus, gastrocnemius, and plantaris.
  • flexion is limited by quadriceps, cruciate ligaments, and by opposing soft tissues (calf and thigh).
• Extension is primarily by the quadriceps and tensor fascia lata.
  • innervation by femoral nerve and superior gluteal nerve.
  • extension is limited by hamstrings, cruciate ligaments, collateral ligaments, posterior joint capsule.
• Medial rotation of tibia is primarily by popliteus, semitendonosus, gracilis, and sartorius.
  • innervation by tibial nerve, tibial portion sciatic, obturator, and femoral nerves respectively.
  • limitation of movement by collateral ligaments
• Lateral rotation of tibia is primarily by biceps femoris.
  • innervation by tibial and peroneal portions of sciatic nerve.
• limitation of movements by collateral ligaments.
  • Abduction and adduction is limited by the medial and lateral collateral ligaments.

Fascial specializatons

• patellar retinaculum
• iliotibial tract
• investing fascia

Vascular supply

• Genicular anastomosis
  • Superior and inferior, medial and lateral genicular arteries, and middle genicular from the popliteal artery.
  • descending genicular artery from femoral artery and descending branch from lateral femoral circumflex artery
  • Fibular circumflex artery, and anterior and posterior tibial recurrent arteries from the anterior and posterior tibial artery
  • Accompanying veins

Innervation (Hilton's Law)

• small branches of the femoral, obturator, and sciatic, and tibial nerves pierce the joint capsule.

"Screw Home"

• Consider when the knee is extended with the foot planted on the ground. In this case, the tibia is fixed by virtue of the planted foot. Thus, rotation of the knee occurs as movement of the femur. The femur rotates medially as the knee "locks" in extension. The lateral femoral condyle is smaller than the medial femoral condyle. As the knee is extended the smaller condyle moves through its arc before the medial condyle. Thus, movement stops at the lateral condyle while the femoral medial condyle continues to move further posteriorly. This movement results in a medial rotation of the femur.
• This medial rotation torques the joint capsule and it's ligamentus specializations (medial and later collateral ligs). The "twisting" of the capsular ligaments causes the region to tighten. This firmly approximates the femoral condyles to the tibial plateau and "locks" the knee. The femur "screws" medially onto the tibial plateau due to the larger medial condyle and the twisting of the capsular ligaments. On extension, the knee goes through a "screw home" rotation that results in "close packing."
• The final medial rotation of the femur is driven by the line of gravity moving anterior to the axis of the knee joint. Thus, locking the knee is driven by gravity. Unlocking the knee requires muscular involvement. The popliteus, having lateral superior to medial inferior attachments, posterior to the axis of the knee, can to lateral rotate the femur (reverse origin and insertion) and, thus, unlock the knee joint.

Discuss the anatomy of the pericardial sac, including mention of the layers, relationships, stabilization, vascularization, innervation, and lymphatic drainage. Comment on the clinical ramifications of excessive fluid in the pericardial cavity. (12 pts)

Pericardial Cavity and Sac

• Within the middle mediastinum
• The pericardial cavity is a collapsed serous cavity within the pericardial sac that surrounds, but does not containing, the heart
• The content of the pericardial cavity is, under nonpathological conditions, a small amount of serous fluid
• Provides reduced friction to accomodate movement of the heart

Layers of the sac and cavity

• Fibrous layer of parietal pericardium - outermost
• Serous parietal pericardium - lining the inner surface of the fibrous parietal pericardium
• Visceral pericardium (epicardium) - outer surface of myocardium

Relationships, Stabilization, and Reflections

• Superior - Superior mediastinum and contents
  • Support by attachments to great vessels and by arterial mesocardium
  • Reflections at the arterial mesocardium help to define the transverse sinus
• Inferior - diaphragm
  • Support by the central tendon and the inferior vena cava
• Anterior - anterior mediastinum
  • Support by pericardiosternal ligaments
  • Thymus
  • Internal thoracic, musculophrenic, and anterior intercostal vessels
  • Sternocostal recesses
• Posterior - posterior mediastinum and contents (esophagus, aorta, and much more)
  • Support by contents of posterior mediastinum
  • Reflections at the venous mesocardium define the oblique sinus
• Lateral (left and right) - pleural cavities
  • Within the adjacent endothoracic fascia - pericardiacophrenic vessels, phrenic nerves, vagus nerves,
  • Sternocostal recesses

Vascularization

• Fibrous pericardium - based on location, the pericardicophrenic, internal thoracic, anterior intercostal, musculophrenic, bronchial, esophageal, and superior phrenic vessels
• Visceral pericardium - based on loction, the coronary arteries and branches

Lymphatic Drainage

• mediastinal nodes - bronchopulmonary nodes - paratracheal nodes - bronchomediastinal lymph truncks
• parts of fibrous paracardium drain to parasternal nodes
• Parasternal and paratracheal drainages combine to form the bronchomediastinal lymph trunks
• right - right lymph duct into brachiocephalic v.
• left - thoracid duct or independently into left brachiocephalic

Innervation

• Fibrous pericardium - somatic (sharp pain) innervation by phrenic and intercostal nerves
• Visceral pericardium - visceral (dull pain) innervation by superficial and deep cardiac plexuses which, in turn, are formed by cardiac nerves derived from the vagus nerves and from the sympathetic trunks
• Anatomic pathways for pain sensation (visceral) from the visceral pericardium follow - cardiac plexuses, splanchnic nerves, rami communicantes, spinal nerve ventral ramus (intercostal nerve), dorsal root (dorsal root ganglion at T2), spinal cord at T2 (T1-4)

Cardiac Tamponade

• Fluid in the pericardial sac limits movement of the heart and, thus, compromises cardiac output.

Discuss the boundaries (6 directions), contents, and relationships of structures in the the superior mediastinum (10 pts)

General

• Between manubrium and lateral aspect of upper 4 thoracic vertebrae
• Asymetry of arteries and viens in the superior mediastinum

Boundaries

• General - Wedge shaped
• Superior - Projection from jugular notch to T1 vertebra
• Inferior - Projeciton from sternal angle to T4 vertebra
• Anterior - Posterior surface of manubrium
• Posterior - Transverse processes of first four throacic vertebra
• Lateral left - reflection of mediastinal parietal pleura to costal pariental pleura - left lamina sternal pericardial ligament
• Lateral right - reflection of mediastinal parietal pleura to costal pariental pleura - right lamina sternal pericardial ligament

Relationships to external structures

• Superior - Cupula, thoracic inlet, and neck
• Inferior - Anterior, middle (pericardium), and posterior mediastinum
• Anterior - manubrium
• Posterior - Transverse processes of first four throacic vertebra
• Lateral left - pleural cavity and left lung
• Lateral right - pleural cavity and right lung

Contents and relations from anterior to posterior

• Internal thoracic arteries - short pathway within mediastinum
  • Superior - base of neck, subclavian artery
  • Inferior - anterior mediastinum (not considered content of anterior mediastinum
  • Anterior - most lateral aspect of manubrium
  • Posterior - ascending aorta
  • Lateral - sternal pericardial ligament, mediastinal pleura, pleural cavity, lungs
  • medial - sternal pericardial ligament, mediastinal pleura, pleural cavity, lungs
• Thymus - directly posterior to manubrium (largely replaced by fat and connective tissue in the adult)
  • Superior - base of neck
  • Inferior - may extend into anterior mediastinum
  • Anterior - manubrium
  • Posterior - ascending aorta
  • Lateral left - sternal pericardial ligament, mediastinal pleura, pleural cavity, lungs
  • Lateral right - sternal pericardial ligament, mediastinal pleura, pleural cavity, lungs
• Ascending aorta -
  • Superior - base of neck, brachiocephalic artery
  • Inferior - pericardium
  • Anterior - thymus
  • Posterior - descending aorta
  • Lateral left - mediastinal parietal pleura
  • Lateral right - superior vena cava and brachiocephalic vv
• Superior vena cava -
  • Superior - base of neck, brachiocephalic vv
  • Inferior - pericardium
  • Anterior - thymus
  • Posterior - trachea, right bronchus
  • Lateral left - ascending aorta
  • Lateral right - phrenic nerve, mediastinal parietal pleura, lung
• Right phrenic nerve and pericardiacophrenic vessels -
  • Superior - base of neck, brachiocephalic vv
  • Inferior - pericardium (anterior to hilum)
  • Anterior - mediastinal pleura
  • Posterior - trachea, right bronchus
  • Lateral left - superior vena cava
  • Lateral right - mediastinal parietal pleura, lung
• Left phrenic nerve and pericardiacophrenic vessels -
  • Superior - base of neck
  • Inferior - pericardium (anterior to hilum)
  • Anterior - mediastinal pleura
  • Posterior - left bronchus, vagus nerve
  • Lateral left - mediastinal parietal pleura, lung
  • Lateral right - anterior aspect aortic arch
• Aortic arch -
  • Superior - brachiocephalic artery, left common carotid artery, left subclavian artery, base of neck
  • Inferior - left recurrent laryngeal nerve, pericardium
  • Anterior - ascending aorta
  • Posterior - descending aorta
  • Lateral left - anterior: phrenic nerve and pericardiacophrenic vessels, posterior: left vagus nerve, superficial cardiac plexus
  • Lateral right - left recurrent laryngeal nerve, trachea and bifurcation,
• Trachea and bifurcation - centrally located with superior mediastinum
  • Superior - base of neck
  • Inferior - pericardium, posterior mediastinum
  • Anterior - ascending aorta, superior vena cava, deep cardiac plexus, paratracheal lymph nodes
  • Posterior - left: left recurrent laryngeal nerve, middle: esophagus, thoracic duct, right: right vagus nerve
  • Lateral left - aortic arch
  • Lateral right - arch of the azygos v
• Arch of the azygos vein
  • Superior - superior vena cava
  • Inferior - right main bronchus
  • Anterior - cupula, root of neck
  • Posterior - thoracic sympathetic trunk
  • Lateral left -trachea, right vagus (deep to arch), esophagus
  • Lateral right - mediastinal pleura, pleural cavity, lung
• Left Vagus
  • Superior - common carotid artery, cupula, root of neck
  • Inferior - hilum of lung (passes posterior to hilum)
  • Anterior - phrenic nerve, mediastinal pleura
  • Posterior - descending aorta, esophagus
  • Lateral left - mediastinal pleura
  • Lateral right - aortic arch
• Left recurrent laryngeal nerve
  • Superior - root of neck, cupula
  • Inferior - hilum of lung, posterior mediastinum
  • Anterior - aortic arch: ligamentum artiosum, tracheoesophageal groove: trachea
  • Posterior - aortic arch: descending aorta, tracheoesophageal groove: esophagus
  • Lateral left - aortic arch: superficial cardiac plexus, tracheoesophageal groove: aortic arch
  • Lateral right - aortic arch: trachea, tracheoesophageal groove: trachea, esophagus
• Right Vagus
  • Superior - brachiocephalic artery, cupula, root of neck
  • Inferior - hilum of lung (passes posterior to hilum)
  • Anterior - super vena cava
  • Posterior - azygos vein, esophagus
  • medial - trachea, right bronchus
  • Lateral - arch of the azygos vein
• Esophagus
  • Superior - root of neck, cupula
  • Inferior - posterior mediastinum
  • Anterior - middle: trachea, left: left recurrent laryngeal nerve, right: right vagus nerve, right main bronchus
  • Posterior - middle: thoracic duct, right posterior intercostal vein and artery, left: accessory hemiazygos vein, right: mediastinal pleura
  • Lateral left - descending aorta, left vagus nerve
  • Lateral right - arch of the azygos vein, mediastinal pleura
• Descending aorta
  • Superior - cupula, root of neck
  • Inferior - posterior mediastinum
  • Anterior - aortic arch
  • Posterior - accessory hemiazygos vein
  • Lateral left - mediastinal pleura
  • Lateral right - thoracic duct, esophagus
• Thoracic duct
  • Superior - root of neck
  • Inferior - posterior mediastinum
  • Anterior - left: descending aorta, right: esophagus
  • Posterior - right posterior intercostal artery and vein,
  • Lateral left - accessory hemiazygos vein
  • Lateral right - esophagus, mediastinal pleura
• hemiazygos vein (and/or accessory hemiazygos vein)
  • Superior - cupula, root of neck
  • Inferior - posterior mediastinum
  • Anterior - descending aorta
  • Posterior - left thoracic sympathetic trunk
  • Lateral left - mediastinal pleura
  • Lateral right - vertebral body, thoracic duct
• Right posterior intercostal arteries
  • Superior - cupula, root of neck
  • Inferior - posterior mediastinum
  • Anterior - right posterior intercostal veins, accessory hemiazygos vein, descending aorta, thoracic duct, esophagus
  • Posterior - vertebral bodies
  • Lateral left (medial) - vertebral bodies
  • Lateral right - thoracic sympathetic trunk, mediastinal pleura
• Thoracic Sympathetic trunk
  • Superior - cupula, root of neck
  • Inferior - posterior mediastinum
  • Anterior - right: arch of the azygos vein, left: accessory hemiazygos vein
  • Posterior - body of rib, intercostal nerves
  • Lateral - mediastinal pleura
  • medial - neck of ribs, vertebral bodies

Discuss the boundaries (6 directions), contents, and relationships in the lateral compartment of the leg; include muscles, nerves, vasculature, and fascial specializations. Indicate the function of the lateral compartment of the leg, and define the effects of injury to this comparatment on the actions of the foot and support of the arches (10 pts)

General

• General comments here.

Fascial specializations

• crual fascia - investing fascia making up the lateral boundary of the lateral compartment
• Anterior intermuscular septum attaches to fibula - separates the lateral from the anterior compartment
• Posterior intermuscular septum attaches to fibula - separates the lateral from the posterior compartment

Boundaries

• Superior - crual fascia knee joint capsule
• Inferior - continuous with dorsum of foot
• Anterior - anterior intermuscular septum
• Posterior - posterior intermuscular septum
• Lateral - crual fascia between anterior and posterior intermuscular septa
• Medial - fibula

Contents and relationships

• Muscles
  • peroneus longus
  • peroneus brevis
• Nerves
  • Deep peroneal nerve - pierces posterior and anterior intermuscular septa (crual fascia)
    • crosses lateral aspect of the neck of the fibula prior to entering anterior compartment
    • supplies a twig to knee joint and, commonly, a motor branch to peroneus longus prior to entering anterior compartment
  • Superficial peroneal nerve - pierces posterior intermuscular to enter lateral compartment
    • crosses neck of fibula slightly inferior to deep peroneal nerve and more longitudinal
    • extends inferior between peroneus longus and brevis and provides motor innervation to peroneus brevis and peroneus longus
    • pierces the crual fascia to supply a cutaneous distribution on the dorsum of the foot
• Vasculature
  • fibular circumflex artery - superior in compartment
  • peroneal artery (posterior compartment) - branches pierce posterior intermuscular septum to supply middle of lateral compartment
  • branches of the malleolar anastomosis supply the inferior aspect of the lateral compartment

Actions at the foot

• Peroneus longus and brevis are primarily everters of the foot and secondary for plantar flexion

Support of the arches of the foot

• Peroneus longus and brevis support the lateral longitudinal arch as "suspension" elements
• Peroneus longus supports the transverse arch as a "tie-beam" element
• Peroneus longus supports the medial longitudinal arch as a staple - splays across plantar tarsal joints

Injury

• Damage to the lateral compartment would cause the foot to be inverted due to unopposed inverters (tibialis anterior/posterior). The lateral longitudinal arch would weaken due to reduced superior support. The transverse arch would weaken to do reduced transverse support (tie beam). The medial longitudinal arch would be minimally effected.

Discuss the superior gluteal nerve - its location and course in the gluteal region. Explain what may have occur with an intragluteal injection to the right buttock and why there could be a gate problem. Will both extremities be altered insofar as actions? Include the actions of muscles innervated by the superior gluteal nerve, as well as origins and insertions. How would the patient compensate for this injury during walking? (10 pts)

Anatomy of the superior gluteal nerve

• Leaves the pelvic cavity by way of the greater sciatic foramen to enter the gluteal region
• Enters the gluteal region superior to the piriformis muscle
• Extends laterally across gluteal region in a fascial plane deep (anterior) to gluteus medius and superficial (posterior) to gluteus minimus and supplies these two muscles
• Extends as far laterally as tensor fascia lata and supplies this muscle
• Vasculature supply is largely by the superior gluteal artery and vein

Intragluteal injection

• Accidental injection into the upper medial quadrant of the gluteal region puts the superior gluteal nerve at risk
• Upper lateral quadrant is preferred for injection because the super gluteal nerve has ramified prior the reaching this location

Origins and insertions based on proximal/distal

• Gluteus medius - origin: ala of ilium between anterior and posterior lines, insertion: superior greater trochanter
• Gluteus minimus - origin: ala of ilium between anterior and inferior gluteal lines, insertion: superior greater trochanter anterior to gluteus medius
• Tensor fascia lata - anterior superior iliac spine, insertion: head of fibula by way of joint capsule and iliotibial tract

Actions

• Gluteus medius - abduction of thigh, medial rotation
• Gluteus minimus - abduction of thigh, medial rotation
• Tensor fascia lata - abduction of thigh
• Functional reversal for all three muscles - abduction (stabilization) of pelvis when lower extremity is planted

Disruption of gate - both lower extremities are effected

• Paralysis of gluteus medius and minimus causes dropping of the pelvic girdle opposite to the side of injury. Normally, during walking, gluteus minimus and gluteus medius pull downward on the pelvic girdle opposite to the limb in swing phase. This action stabilizes the pelvic girdle. The gluteus minimus and medius mm are viewed as arising from the femur (greater trochanter) and inserting upon the ilium. This demonstrates a reversal of origin and insertion. When gluteus medius and minimus are paralyzed the pelvis drops to the side of swing phase. In order to restore the line of gravity, the patient leans to the side of the injury. The resulting gate is known as Trendelenberg's gate (gluteal waddle).

Discuss the structure of the left ventricle, including the atrioventricular and semilunar valves. Would the pain in her left upper extremity be related to a problem with the heart? (10 pts)

General

• Between the left atrium and ventricle is the bicuspid atrioventricular ( Mitral) valve
• Between the left ventricle and aorta is aortic semilunar valves
• Healthy valves permit little to no back flow
• Integrated with the skeleton of the heart
• Located in the ventricles (atrioventricular valves) and at the base of the arterial trunks (semilunar valves)
• The atrioventricular valves and the semilunar valves are closed by the pressure (they are not closed by muscular contraction applied to the cusps)
• Pulmonary veins to left atria to biscupid (mitral) valve to left ventricle to aortic valve to systemic circulation to coronary arteries during diastole
• Atrioventricular valves close (lub) during systole whereas the semilunar valves close (dub) during diastole

Structure

• Cone shaped having the aortic vestibule as the outflow path toward aortic valve
• Myocardial walls are thickest for the left ventricle
• Trabeculae carneae are fine and delicate relative to the right ventrical
• Interventricular septum - pars muscularis and pars membranacea
• Lymph drainage along coronary arteries toward tracheobronchial nodes and then bronchiomediastinal lymph trunks
• Branches of the AV bundle run through interventricular septum and outer wall

Atrioventricular valve - Biscuspid (Mitral Valve)

• Between the left atria and the left ventricle
• Two cusps open into the left ventricle
• Two papillary muscles - anterior and posterior
• Resists extreme pressure generated by left ventricular contraction
• Cusps are stabilized by chorda tendeneae - fibrous cords between cusps and papillary muscles
• Ventricular contraction raises pressure - blood pools on ventricular side of cusps causing the cusps to approximate each other and close the valve
• Adjustments by the papillary muscles and chorda tendeneae provide support and prevent eversion of the cusps into the atria
• Note - contraction of the papillary muscles, in the absence of ventricular contraction, open, not close, the atrioventricular valves

Semilunar valve - aortic valve

• Located at the base of the aortic trunk
• Prevents reverse flow from the aorta to the left ventricle during diastole
• Negative pressure of left ventricle and elastic recoil of systemic arteries move aortic blood toward the valve
• Opened by blood flow during systole - cusps move toward aortic wall and block coronary ostia
• Three cusps - no papillary muscles or chorda tendeneae
• Left and right coronary cusps (feed coronary arteries) and a non-coronary cusp
• Nodule - weighted fibrous thicking at the midline of the free edge of each cusp aids in approximating the cusps and closing the valve
• Aortic sinus - space between the wall of the aorta and each cusp
• Valve closed by pressure - blood pools in the aortic sinuses during diastole and aproximates the nodules

Referred pain to medial aspect of arm

• Anatomic pathways for pain sensation (visceral) from the heart (epicardium) follow - cardiac plexuses, splanchnic nerves, rami communicantes, spinal nerve ventral ramus (intercostal nerve), dorsal root (dorsal root ganglion at T2), spinal cord at T2 (T1-4)
• Anatomic pathways for pain sensation (somatic) from the medial arm follow - intercostobrachial nerve (T2), intercostal nerve, spinal nerve (ventral ramus), dorsal root (dorsal root ganglion at T2), spinal cord at T2.
• Cross talk is thought to occur within the dorsal ganglia or within the spinal cord (CNS).

Comment - Blood flow to the coronary vessels

• Coronary arteries are perfused during diastole when heart muscle is relaxed
• During systole the coronary ostia are blocked by the open cusps of the aortic valve
• During diastole blood pools in the aortic sinuses and closes the aortic valve.
• Blood driven into the left and right aortic sinuses enters into the ostia of the coronary arteries.
• Primary blood supply to the left ventricle and the interventricular septum is by the left coronary artery
• Right coronary artery supplies part of posterior wall of left ventricle on diaphragmatic surface

Discuss the structure and function (including blood flow to the coronary vessels) of the semilunar valves and the atrioventricular valves (12 pts)

The valves of the heart direct blood flow in one direction

• Between the atria and the ventricles are the atrioventricular valves
• Between the ventricles and arterial trunks are the semilunar valves
• Healthy valves permit little to no back flow
• Integrated with the skeleton of the heart
• Located in the ventricles (atrioventricular valves) and at the base of the arterial trunks (semilunar valves)
• The atrioventricular valves and the semilunar valves are closed by the pressure (they are not closed by muscular contraction applied to the cusps)
• IVC to rt atria to tricuspid to rt ventricle to pulmonary valve to pulmonary artery to lungs to pulmonary veins to left atria to biscupid (mitral) valve to left ventricle to aortic valve to systemic circulation to coronary arteries during diastole
• Atrioventricular valves close (lub) during systole whereas the semilunar valves close (dub) during diastole

Atrioventricular valve - Tricuspid

• Between the right atria and the right ventricle
• Three cusps open into the right ventricle
• Three papillary muscles (extensions of trabeculae carne) - anterior, posterior, and septal
• Cusps are stabilized by chorda tendeneae - fibrous cords between cusps and papillary muscles
• Ventricular contraction raises pressure - blood pools on ventricular side of cusps causing the cusps to approximate each other and close the valve
• Adjustments by the papillary muscles and chorda tendeneae provide support and prevent eversion of the cusps into the atria
• Note - contraction of the papillary muscles, in the absence of ventricular contraction, open, not close, the atrioventricular valves

Atrioventricular valve - Biscuspid (Mitral Valve)

• Between the left atria and the left ventricle
• Two cusps open into the left ventricle
• Two papillary muscles - anterior and posterior
• Resists extreme pressure generated by left ventricular contraction

Semilunar valve - aortic valve

• Located at the base of the aortic trunk
• Prevents reverse flow from the aorta to the left ventricle during diastole
• Negative pressure of left ventricle and elastic recoil of systemic arteries move aortic blood toward the valve
• Opened by blood flow during systole - cusps move toward aortic wall and block coronary ostia
• Three cusps - no papillary muscles or chorda tendeneae
• Left and right coronary cusps and a non-coronary cusp
• Nodule - weighted fibrous thicking at the midline of the free edge of each cusp aids in approximating the cusps and closing the valve
• Aortic sinus - space between the wall of the aorta and each cusp
• Valve closed by pressure - blood pools in the aortic sinuses during diastole and aproximates the nodules

Semilunar valve - pulmonary valve

• Located at base of pulmonary trunk
• Prevents reverse flow from the pulmonary trunk to the right ventricle during diastole
• Operation is the same as aortic valve except that there are not coronary cusps (no ostia in pulmonary trunk)

Blood flow to the coronary vessels

• Coronary arteries are perfused during diastole when heart muscle is relaxed
• During systole the coronary ostia are blocked by the open cusps of the aortic valve
• During diastole blood pools in the aortic sinuses and closes the aortic valve.
• Blood driven into the left and right aortic sinuses enters into the ostia of the coronary arteries.

Discuss the muscles and ligaments involved with flexion and extension of the digits of the foot, and relate this to function

General Comment

• Flexion of the digits, relative to extension, is more specific because of the independence of flexor tendons relative to extensor tendons

Primary Flexors

• Flexor Hallucis longus - inserts at base of distal phalynx of digit 1
  • Innervated by the tibial nerve
  • flexes the IP joint plus the MP and ankle joint
  • Origin from posterior compartment of leg - intersseous membrane and fibula
  • crosses ankle inferior to sustentaculum tali and within flexor sheath
  • receives guidance from the sesamoid bones within the lateral and medial heads of the flexor digitorum brevis
• Flexor hallucis brevis - inserts at base of proximal phalanx of digit 1
  • Innervated by the medial planter nerve
  • flexes the MP joint
  • lateral and medial head each host a sesamoid bone near the head of the first metatarsal
  • sesamoid bones provide a "groove" to guide the tendon of flexor hallucis longus toward the distal phalanx
  • sesamoid bones provide site of attachment for the abductor hallucis and the adductor hallucis
• Flexor digitorum longus - inserts on the base of the distal phalanx of digits 2-4
  • Innervated by the
  • flexes the distal IP joint plus the proximal IP, MP, and ankle
  • lumbricals arise from the lateral sides of the the tendons - extend IP and flex MP
  • origin from the posterior compartment of the leg - tibia and interosseous membrane
  • crosses ankle superior to sustentaculum tali and within the flexor sheath
• Flexor digitorum brevis - inserts at the base of the middle phalanx of digits 2-4
  • Innervated by the
  • flexes the proximal IP joint plus the MP joint
  • origin from the calcaneous - intrinsic to the foot
  • tendons are approximated to planter surface of flexor digitorum longus
  • tendon splits and inserts onto the sides of the base of the middle phalanx
  • the tendon of flexor digitorum longus passes through the split tendon without tethering to the flexor digitorum brevis
  • independent action at the distal and proximal IP joint is preserved relative to the extensors (extensor hood)
• Flexor digiti minimi - inserts at the base of the middle phalanx of digit 5
  • Innervated by the
  • flexes the proximal IP joint plus the MP joint
  • intrinsic to the foot

Primary Extensors

• Extensor hallucis longus - inserts on the distal and proximal phalanges of digit 1
  • Innervated by the
  • extends the IP joint plus the MP joint plus the ankle
  • origin from the anterior compartment of the leg - tibia and interosseous membrane
  • stabilized by the superior and inferior retinacula
  • tenoned receives a lateral attachment at the level of the head of the first metatarsal from extensor hallucis brevis
  • The tendons of extensor hallucis longus and brevis are tethered to each other and can not act independently.
• Extensor hallucis brevis - inserts on the distal and proximal phalanges of digit 1 (via tendon of extensor hallucis longus)
  • extends the IP and MP joint
  • intrinsic to the dorsum of the foot
  • tendon attaches to lateral side of the tendon of extensor hallucis longus or to the proximal phalanx
  • origin is from the anterolateral aspect of the calcaneous
  • has been considered a named slip of extensor digitorum brevis
• Extensor digitorum longus - inserts on the bases of the middle and distal phalanges of digits 2-5 be way of the extensor hood
  • extends the distal and proximal IP joints plus the MP and the ankle joints
  • origin from the anterior compartment of the leg - interosseous membrane and the fibula
  • stabilized by the superior and inferior extensor retinaculae
  • tendons receive lateral attachments from the extensor digitorum brevis on digits 2-4 at level of head of metatarsal
  • the combined tendons of the extensor digitorum longus and brevis contribute to the extensor hood
  • extensor hood has a center insertion on the middle phalanx and sends two lateral bands to insert on the sides of the base of the distal phalanx
  • extensor hood also receives fibrous contributions from the lumbricals and the interossei
  • The extensor digitorum longus and brevis are tethered to each other by the extensor hood and can not act independently
• Extensor digitorum brevis - inserts on the extensor hood and, thus, to the bases of the middle and distal phalanges of digits 2-4 (not 5)
  • extends the distal and proximal IP joints plus the MP
  • origin is from the anterolateral aspect of the calcaneous
  • tedons attach to the extensor at the lateral aspect of the extensor digitorum longus at the level of the head of the metatarsals

Additional comments

• Mesotendons (vincula) drived from tendon sheaths provide vascular and nervous supply to the distal flexor tendons
• It is the relative independence of the flexor tendons and the unique action of the lumbricals that permit greater specificity of flexion.
• The deep and superficial transverse metatarsal ligaments stabilize the heads of the metatarsals and contribute to fine movement.
• Collateral ligaments at the MP and IP joints stablize flexion and extension.

Review the boundaries (6 in number) and contents (vasculature, nerves, lymphatics) of the femoral triangle. State the relationship of structures entering and leaving this region. (12 pts)

Superior Boundary

• Inguinal ligament spanning the anterior superior iliac spine and pubic tubercle (including a figure would help)
  • contents of the muscular and vascular lacunae enter the femoral triangle (discuss relations)
• Vascular lacuna.
  • The vascular lacuna is located posterior to the inguinal ligament, medial to the iliopectineal arch, lateral to the lacunar ligament, and anterior to the pectineal fascia.
  • The contents include, from the lateral to medial, the femoral artery, the femoral vein, and the femoral canal.
  • These contents are contained within compartments of the femoral sheath. These compartments are separated by septa that run between the inguinal ligament and the pectineal fascia.
  • Femoral hernias occur in this region.
  • abdominal viscera may enter the femoral canal through the femoral ring.
• Muscular lacuna
  • posterior to inguinal ligament and lateral to iliopectineal arch
  • femoral nerve enters femoral triangle deep to iliacus fascia
  • lateral femoral cutaneous nerve enters femoral triangle lateral to femoral nerve and near anterior superior iliac spine

Inferior Boundary

• adductor canal at the apex
• At the apex of the femoral triangle is the beginning of the adductor canal.
• The femoral artery and vein, and the saphenous nerve enter the adductor canal.
  • artery anterior to vein - note: this relation betrays relation of popliteal vessels
• The adductor canal is bounded anteromedially by the sartorius muscle. Anterolaterally, it is bounded by the vastus medialis. Posteriorly it is bounded by adductor longus and adductor magnus.
• nerve to vastus intermedius enters adductor canal

Lateral Boundary

• sartious
• lateral femoral circumflex a/v exits laterally deep to sartious and between rectus femoris and vasti

Medial Boundary

• adductor longus
• profunda femoral a/v exits posteromedial deep to super border of adductor longus and continues between adductor longus and adductor magnus

Anterior Boundary

• fascia lata and saphenous hiatus (show relations fig)
• the contents of the cribriform fascia exit the femoral triangle at this location
• superficial/external pudendal a/v
• superficial epigastric a/v
• superficial circumflex iliac a/v
• the great saphenous vein
• anterior femoral cutaneous nn pierce fascia lata anterior.

Posterior Boundary

• iliopsoas, pectineus, and possibly parts of adductor brevis and adductor longus
• the medial femoral circumflex a/v exits between iliopsoas and pectineus
• the deep femoral artery exits between iliopsoas and adductor longus

Saphenous Hiatus

• The saphenous hiatus is a specialization of the fascia lata located in the anteromedial thigh just inferior to the inguinal ligament and superficial to the femoral sheath. The lateral margin overlies the femoral artery. The medial aspect overlies the femoral canal. Superiorly is the inguinal ligament. Approximately 2cm inferior to the inguinal ligament is the inferior cornu over which the great saphenous vein forms an arch as it leaves superficial fascia and enters the femoral vein. Notable tributaries of the great saphenous vein within the saphenous hiatus are the external pudendal vein coursing medially, the superficial epigastric vein coursing superiorly, and the superficial circumflex iliac vein coursing laterally and superiorly. Accompanying these veins are branches of the femoral artery. These vessels are piercing through the surrounding cribriform fascia. The distinct lateral margin of the saphenous hiatus is the falciform edge. There are superior and inferior borders referred to as the superior and inferior cornu. Medially, the hiatus is indistinct and blends with the pectineus fascia. The femoral ring is located immediately deep to the medial aspect of the saphenous hiatus. A femoral hernia, if present, can be palpated at this location. Additionally, a femoral pulse can be located and, thus, easy surgical access to a major artery or vein is possible.

Femoral canal

• Lymph funnel shaped lymph channel located in the most medial compartment of the femoral sheath.
• Femoral ring is at the superior opening of this canal.
• Formed by an 1.5cm extension of transversalis fascia from the abdominal cavity into the thigh.
• Exposed to superficial fascia by the saphenous hiatus.
• Site of femoral hernia
  • more common in females because of wider pelvic bones and larger femoral ring.

Describe the lymphatic drainage of the breast (6 pts)

Lateral Drainage

• Laterally, lymph drainage from the breast is into groups of axillary nodes. Most of this drainage is into the pectoral nodes located along pectoral branches of the thoracoacromial vessels. Pectoral nodes drain into the apical nodes located near the apex of the axilla. On the left, the axillary nodes give rise to the subclavian lymphatic trunk. This vessel commonly drains into the thoracic duct and then the angle of internal jugular. The right subclavian duct often drains directly into the venous system. Apical nodes also have drainages into cervical and supraclavicular nodes. Metastatic disease in these nodes is especially difficult to remove.

Medial Drainage

• The medial aspect of the breast is drained by intercostal vessels into parasternal nodes. Parasternal and paratracheal drainages combine to form the bronchomediastinal lymph trunks. Drainage continues into the right lymphatic duct on the right and the thoracic duct on the left.
• The breast is also drained by subcutaneous vessels. These vessels have a wide distribution ranging from the cervical region to the inguinal region and crossing the midline. If the deeper lymph channels are blocked, as may be the case with cancer, subcutaneous drainage may greatly increase and widely disperse cancerous cells.
• axillary notes receive 75% of lymphatic drainage
• pectoral nodes - lateral border of pectoralis major
• apical nodes - beneath the clavicle
• supraclavicular nodes
• cervical nodes
• parasternal nodes
• along the internal thoracic artery
• subcutaneous lymphatics
• distribute to wide area if deep lymphatics are blocked (e.g. cancer)
• left/right differences
• right side into right (subclavian) lymph duct
• left side into thoracic duct and left subclavian v.

Summary

• Laterally, lymph drainage from the breast is into groups of axillary nodes. Most of this drainage is into the pectoral nodes located along pectoral branches of the thoracoacromial vessels. Pectoral nodes drain into the apical nodes located near the apex of the axilla. On the left, the axillary nodes give rise to the subclavian lymphatic trunk. This vessel commonly drains into the thoracic duct and then the angle of internal jugular. The right subclavian duct often drains directly into the venous system. Apical nodes also have drainages into cervical and supraclavicular nodes. Metastatic disease in these nodes is especially difficult to remove. The medial aspect of the breast is drained by intercostal vessels into parasternal nodes. Parasternal and paratracheal drainages combine to form the bronchomediastinal lymph trunks. Drainage continues into the right lymphatic duct on the right and the thoracic duct on the left. The breast is also drained by subcutaneous vessels. These vessels have a wide distribution ranging from the cervical region to the inguinal region and crossing the midline. If the deeper lymph channels are blocked, as may be the case with cancer, subcutaneous drainage may greatly increase and widely disperse cancerous cells.

Discuss the anatomy of the popliteal fossa and include an account of the boundaries, vascular supply, innervation, ligaments, bones, contents, muscles, and relationships. (12 pts)

General comments

• posterior to knee, diamond shaped, fat filled, passage of key structures to the lower limb

Superior boundary - apex of diamond formed by semimembranosus and semitendinosus diverging from biceps femoris

• sciatic n. - enters from posterior thigh deep to hamstrings, divides into tibial (medial) and common peroneal (lateral) nn.

Superior lateral boundary - biceps femoris

• superior lateral genicular a.v. - leaves popliteal fossa femur at lateral femoral epicondyle superior to origin of gastrocnemius

Superior medial boundary - semitendinosus and semimembranosus

• superior medial genicular a.v. - leaves popliteal fossa at medial femoral epicondyle superior to adductor tubercle

Inferior lateral boundary - lateral head of gastrocnemius

• inferior lateral genicular a.v. - leaves popliteal fossa crossing posterior surface of popliteus fascia and arcuate ligament, deep to head of gastrocnemius
• common peroneal n. - leaves popliteal posterior to lateral head gastrocnemius

Inferior medial boundary - medial head of gastrocnemius

• inferior medial genicular a.v. - leaves popliteal fossa posterior surface of tibia near the plateau, deep to head of gastrocnemius

Inferior boundary - apex of diamond formed by convergence of the two heads of gastrocnemius

• posterior tibial a.v. - leaves popliteal fossa deep to the heads of origin of soleus
• sural aa. - leaves popliteal fossa by entering the bellies of gastrocnemius
• branches of tibial n. to the gastrocnemius

Posterior boundary - popliteal fascia (deep fascia), tranisition from fascia lata to crural fascia

• medial and lateral sural nn. - branches for tibial and common peroneal nn.
• short saphenous v. - pierces popliteal fascia to enter the popliteal v.

Anterior boundary - femur, tibial plateau, joint capsule, oblique popliteal lig., arcuate lig., popliteus m.

• popliteal a.v. - enter through adductor hiatus (superior medial anterior in the fossa) as continuation of the femoral vessels.
• middle genicular a. leaves popliteal fossa through the posterior aspect of the joint capsule

Relations within the fossa

• superficial to deep: sciatic n and branches, femoral v., femoral a.

Lymphatic drainage - popliteal lymph nodes

• superficial drainage of leg along channels enter popliteal fossa along with the lesser saphenous v.
• deep drainage of leg enters popliteal fossa along with posterior tibial vessels
• lymph from popliteal fossa ascend along femoral vessels to deep inquinal nodes

Discuss the anatomy of the hip joint. Include an account of the innervation, vascular supply, ligaments, bones and articulations, movements and limitations of movements, and stability. (12 pts)

General comments

• This hip joint is a synovial "ball and socket" joint

Bones and articulations

• head of femur (ball fits into the acetabulum (socket)
• depth of acetabulum is increased by labrum, labrum overlies the transverse acetabulum ligament at the acetabular notch
• acetabular notch bridged by the transverse acetabular lig
• articular cartilage on head of femur and on lunate surface of acetabular fossa
• ligamentum teres attaches to acetabular fossa near transverse acetabular ligament

Ligaments - capsular thickenings

• pubofemoral - from pectin line to intertrochanteric line, resists abduction
• iliofemoral - from anterior inferior iliac spine (deep to rectus femoris straight head) to intertrochanteric line and lessor trochanter (Y-ligament)
  • fibers spiral from superior anterior medial to inferior posterior lateral - resist extension and shorten on extension to stabilize joint
• ischiofemoral - from ischium to greater trochanter and intertrochanteric line, resists hyperextension and flexion

Movements, limitation of movement, innervations, and muscle stabilization

• flexion
  • psoas major - lumbar plexus
  • anterior compartment of thigh - femoral nerve
    • rectus femoris - long head
    • sartorius (lateral rotation)
    • tensor fascia lata
  • limited by trunk and hamstrings
• extension
  • posterior compartment of thigh (hamstrings and posterior adductor magnus) - tibial portion of sciatic
  • gluteus maximus - inferior gluteal nerve
  • limited by ligaments of joint capsule (see above)
• adduction
  • medial compartment of thigh and obturator externus - obturator nerve
  • limited by opposite thigh and ligament to the head of the femur
• abduction
  • gluteus minimus and medius and tensor facia lata - superior gluteal nerve
  • limited by pubofemoral ligament and adductors
• lateral rotation
  • short rotators of gluteal region - lumbosacral plexus
  • long head of the biceps - tibial portion of sciatic
  • sartorius - femoral nerve
  • relatively free - limited by neck of femur and pubofemoral ligament
• medial rotation
  • anterior part of gluteus minimus (medius) - superior gluteal nerve
  • gracilis - obturator
  • semitendonosus and semimembranosus - tibial portion sciatic
  • limited by joint capsule
• Muscles - all muscles that cross the joint contribute to stabilization
  • anterior group - flexors: iliopsoas adds major support, rectus femoris, sartorius
  • medial group - all of the adductors
  • posterior group - extensors: the hamstrings
  • gluteal region - rotators and abductors: the five short lateral rotators, gluteus maximus, medius, and minimus, tensor fascia lata
  • fascial specialization - iliotibial tract
• The hip joint is maximally stable during extension as is the case during quiet standing. The line of gravity falls behind the axis causing to hip to extend. Capsular thickenings (aforementioned ligaments) spiral from posterior to anterior and from medial on the pelvic girdle to lateral on the femur. As the ligaments tighten the capsule shortens similar to twisting a wet towel. This forces the head of the femur deep securely into the acetabular fossa.
• Vascularization
• Cruciate anastomosis
• Innervation of hip joint
• Hilton's law - all nerves that cross the joint provide innervation to the joint tissues

Discuss the collateral circulation of the arterial supply and venous drainage of the thoracic wall, and relate this to the structure (muscles, bones, fascia) comprising the thoracic cage. (10 pts)

General Comments

• The vasculature supply to the thoracic wall travels within the neurovascular plane defined superficially by the internal intercostal muscles and membrane (posterior) and deeply by the subcostal (posterior), innermost intercostal (intermediate), and transversus thoracis (anterior) muscles. The intercostal veins, arteries, and nerves are located inferior to the costal groove of the superior rib defining an intercostal space. From superior to inferior is vein, artery, nerve. Posterior, lateral, and anterior branches of the intercostal vessels leave the neurovascular plane to supply superficial regions of the thoracic wall. The lateral branches further divide into posterior and anterior branches whereas the anterior branches further divide into medial and lateral branches.
• The bulk of the anterior vasculature has the subclavian arteries and brachiocephalic veins as the parent vessels whereas the bulk of the posterior vasculature has the descending aorta (first two intercostal spaces qualified) and azygous system as the parent vessels. The anterior and posterior vasculatures anastomose within the thoracic wall. Thus, the aortic arch can deliver blood directly to the descending aorta or indirectly to the descending aorta by way of the anterior vasculature (subclavian to internal thoracic to anterior intercostals to posterior intercostals to descending). See below for refining considerations.

Arteries

• Posterior intercostal spaces
  • 1-2 Supereme (highest) thoracic artery from costocervical trunk of subclavian artery
  • 3-11 Posterior intercostal arteries from the descending aorta
• Anterior intercostal spaces
  • 1-6 - Internal thoracic artery from subclavian artery
  • 7-9 - Musculophrenic artery from internal thoracic artery
  • 10-11 - Superior epigastric from internal thoracic artery

Veins

• Right posterior intercostal spaces
  • 1 - Supreme (highest) intercostal vein from brachiocephalic vein
  • 2-4 - superior intercostal vein from azygous vein
  • 5-11 - Posterior intercostal veins from azygous vein
• Left posterior intercostal spaces
  • 1 - Supreme (highest) intercostal vein from brachiocephalic vein
  • 2-4 - superior intercostal vein from accessory hemiazygous vein, or brachiocephalic vein, or coronary sinus
  • 5-11 - Posterior intercostal veins from hemiazygous vein
• Anterior intercostal spaces
  • 1-6 - Internal thoracic vein
  • 7-9 - Musculophrenic vein
  • 10-11 - Superior epigastric vein

Discuss the mechanics of breathing, focusing on explaining the basic movements of the thoracic cage and expansion of the lung in respiration. (9 pts)

Anterior posterior - pump handle and costotransverse joint

• cupped tubercle of transverse process results in pump handle of upper ribs
• costochondral and sternochondral joints involved
• The pump-handle movement of respiration refers to the movements of the upper 6 ribs during breathing. During inspiration there is an increase in the anterior-posterior diameter of the thorax. The sternum moves superiorly and anteriorly in accord with rib movements occurring at the costovertebral, costotransverse, costochondral, and sternochondral joints. Relative to the lower ribs, the costotransverse joint articulation at the transverse process is cupped and accommodates the tubercle of the rib. This articulation permits the rib to rotate on a transverse axis. A slight downward movement at the head of the rib is amplified distally at the sternum. This movement is transferred to the sternum by the costochondral and sternochondral joints. The result is that the sternum raises on inspiration much like the raising of a pump-handle when drawing water from the depths of a well

transverse - bucket handle and costotransverse joint

• planar tubercle of transverse process permits an outward sliding of the rib and results in bucket handle of lower ribs
• costochondral and sternochondral joints involved

vertical - diaphragmatic

• phrenic n., pericardiacophrenic vessels, ant. post. intercostal vessels
• Upon diaphragmatic contraction the height of the diaphragmatic dome drops to increase the vertical extent of the thoracic cavity.
• capillary effect, negative pressure, etc.
• pneumothorax - air enters and breaks capillary effect, loss of negative pressure, the lung collapses

Review the lymphatic drainage of the lung. (5 pts)

Drainage

• Pulmonary nodes of each lung drain toward bronchopulmonary nodes
• Bronchopulmonary nodes drain into tracheobronchial nodes
• oin drainage from parasternal nodes to form bronchomediastinal lymph trunks
• Bronchomediastinal trunks drain into the subclavian vv.
• Possible right and left lung differences
• Right into right lymphatic duct - bracheocephalic v.
• Left into thoracic duct - bracheocephalic v.

Clinical Note

• Large paratracheal nodes may compress lung (middle lobe syndrome)
• Adhesions of visceral and parietal pleura introduces alternative drainage patterns.

Discuss the anatomy of the posterior compartment of the thigh, including function, boundaries, relationships, innervations, and vascularization, along with a definition of the hamstring muscles. (10 pts)

Function

• The hamstring muscles, arising from the ischial tuberosity and inserting on the tibia, are biarticulate. Thus, they act at both the hip (extension) and the knee (flexion). Semimembranosus and semitendinosus are medial rotators of the knee. Biceps femoris is a lateral rotator at the knee.
• The short head of the biceps, a hybrid muscle, crosses one joint -- the knee joint. It is a flexor and a lateral rotator of the knee.
• The posterior adductor magnum crosses one joint -- the hip joint. It is an extensor of the hip.

Boundaries

• Anterior: adductor magnus, femur, vastus lateralis, lateral and medial intermuscular septa
• Posterior: fascia lata
• Lateral: fascia lata, lateral intermuscular septum
• Medial: fascia lata, medial intermuscular septum
• Superior: Gluteal fold
• Inferior: axis of the knee joint (includes superior aspect of popliteal fossa)

Relationships (see boundaries)

• Deepest in the posterior compartment is the adductor magnus. Perforating arteries pierce the adductor magnus medial to this muscle's insertion along the linea aspera of the femur. The most posterior fibers of adductor magnus extend to the adductor tubercle of the medial femoral epicondyle. The adductor hiatus results from a discontinuity of insertion along the inferior aspect of the linea aspera.
• The semimembranosus and semitendinosus course downward from the ischial tuberosity. Both muscles deviate to the medial side. Semitendinosus crosses posterior to the knee and then turns anterior to insert with the pes anserinus. Semimembranosus is closely applied to the anterior (deep) surface of semitendinosus. It crosses posterior to the knee and inserts on the postero-medial aspect of the medial tibial condyle.
• The long-head of the biceps courses downward from the ischial tuberosity and deviates to the lateral side as it approaches the knee. The tendon of insertion crosses posterior to the knee and inserts on the postero-lateral aspect of the lateral tibial condyle and on the head of the fibula. The short-head of the biceps arises from the middle third of the femur and joins the long-head in the lower one-third of the thigh.
• The sciatic nerve enters the posterior thigh from the gluteal region passing on the anterior (deep) surface of the inferior free edge of the gluteus maximus. It lies lateral to the ischial tuberosity and is applied to the posterior surface of the adductor magnus (medial to femur). The sciatic nerve courses downward between biceps femoris and adductor magnus. At the inferior 1/3 of the thigh the sciatic nerve deviates medially as the biceps deviates laterally. In the superior aspect of the popliteal fossa the sciatic nerve branches into the common peroneal nerve and the tibial nerve.
• The posterior femoral cutaneous nerve of the thigh follows the medial posterior aspect of the sciatic nerve.

1. Innervations

• The hamstring muscles and the posterior adductor magnus are innervated by the tibial portion of the sciatic nerve. These branches occur in the gluteal region and in the superior thigh. They branch from the medial side of the sciatic nerve. The short head of the biceps receives a lateral branch of the sciatic nerve derived from the peroneal portion.
• The posterior cutaneous nerve of the thigh sends branches posteriorly that pierce the fascia lata to provide cutaneous innervation to the posterior aspect of the thigh as far inferiorly as the lower reaches of the popliteal region.

1. Vascularization

• The upper 1/3 of the posterior compartment receives vascular supply from the inferior gluteal, medial and lateral circumflex, and 1st perforating vessels. The sciatic nerve receives the arteria commitans nervi ischiadici from the inferior gluteal vessels. This vessel is subsequently augmented by the perforating vessels and branches of the popliteal vessels.
• The middle 1/3 of the thigh receives the perforating vessels from the profunda femoral vessels. These 4-6 vessels perforate the insertions of the adductor magnus along the medial border of the femur.
• The lower 1/3 of the posterior compartment receives vascular from the popliteal vessels in addition to the lower perforating vessels.

1. Definition of the hamstrings

• The hamstring muscles: 1) arise from the ischial tuberosity, 2) are biarticulate (cross two joints), and 3) are innervated by the tibial portion of the sciatic nerve.
• They are the semimembranosus, semitendinosus, and long-head of the biceps femoris

Discuss the anatomical relationships of the piriformis muscle. Furthermore, describe the course of the superior gluteal nerve in the gluteal region, and the functional deficits and compensations(s) resulting from injury. (10 pts)

General Comments

• The upper medial quadrant injection put the superior gluteal nerve at risk. Disruption of gate is largely due to dropping of the pelvic girdle opposite to the injury. When the lower limb opposite to the injury is raised (swing phase) the pelvis sags to that side. Normally, gluteus minimus and gluteus medius pull downward on the pelvic girdle opposite to the limb in swing phase. This keeps raises the opposite side upward during swing phase. This demonstrates a reversal of origin and insertion. In this case, opposite of embyologic origin and insertion, the gluteus minimus and medius mm are viewed as arising from the femur (greater trochanter) and inserting upon the ilium. In order to restore the line of gravity, the patient leans to the side of injury. The resulting gate is known as Trendelenberg's gate (gluteal waddle).

Relations of piriformis - superficial is gluteus maximus

• Piriformis enters the gluteal region by way of the greater sciatic foramen). It inserts upon the supero-posterior greater trochanter.
  • Superior - superior gluteal n.a.v., gluteus medius, gluteus minimus
  • Inferior - inferior gluteal n.a.v., sciatic nerve, superior gemellus (obturator internus, inferior gemellus, quadratus femoris)
  • Anterior - sciatic nerve, posterior cutaneous nerve of the thigh, gluteus minimus, pudendal nerve, internal pudendal vessels
  • Posterior - gluteus maximus, gluteus medius
  • Lateral - greater trochanter of femur, tensor fascia lata
  • Medial - sacrum, pelvic cavity, pudendal nerve, internal pudendal vessels

Relations and innervations of superior gluteal n.

• enters gluteal region superior to piriformis and courses laterally between gluteus medius and minimus to reach tensor fascia lata

Abductors (and medial rotators) of the hip - provide fixation of the pelvic girdle

• gluteus minimus - ileum to superior greater trochanter (deepest of gluteal mm)
• gluteus medius - ileum to superior greater trochanter - posterior to gluteus minimus
• tensor fascia lata - anterior superior iliac spine to iliotibial tract (lateral side of superior fibular head and surrounding area)

Why inject in upper lateral quadrant?

• This region is far removed from the sciatic nerve. The superior gluteal nerve traverses the upper lateral quadrant. However the nerve is ramified by this time. Thus, an injection could not damage the superior gluteal nerve in total. The worse case would be to hit the branch to the tensor fascia lata.

Define the posterior mediastinum and discuss its contents. (10 pts)

Boundaries

• superior - line from T4 toward jugular notch (only that part of line posterior to middle mediastinum)
• inferior - diaphragm posterior to middle mediastinum down to T12
• lateral - fibrous layer of mediastinal parietal pleura
• anterior - posterior to middle mediastinum
• posterior - lateral aspects of vertebral bodies (includes sympathetic trunk)
• medial - the middle of the posterior mediastinum is also midsaggital, i.e., a medial boundary does not exist

Relationships and Contents

• right intercostal aa. - immediately deep to azygos system and sympathetic trunk
• azygos system - azygos v. and hemiazygos v., cross anterior vertebral bodies superficial to right intercostal aa and deep to splanchnic nn.
• thoracic sympathetic trunk - immediately superficial (lateral) to intercostal vessels
• splanchnic nerves - coursing inferior medial and anterior from sympathetic trunk ganglia
• ramus communican - branching posterior from sympathetic trunk ganglia and connecting to spinal nerve at intervertebral foramen
• thoracic duct - superficial to azygos v. between esophagus and aorta, deviates to the left in superior region
• esophagus and esophageal plexus - deviates to the right superiorly and left inferiorly
• aorta - left of vertebral bodies and esophagus
• vagus n. - enters posterior to root of lung
• bifurcation of trachea - immediately superior to esophagus in superior region
• deep cardiac plexus and nerves - anterior to tracheal bifurcation

Discuss the fascial barrier separating the pericardial cavity from the pleural cavity. What structures would be vulnerable to damage in this area? (5 pts)

General Comment

• An infection of the pericardial cavity could erode fascial layers gaining access to the pleural cavity. Beginning within the pericardial cavity proceeding laterally, these layers are:

Fascial Layers

1. serous parietal pericardium
2. fibrous pericardium
3. endothoracic fascia - the phrenic nerve and the pericardiacophrenic vessels are vulnerable within this fascia
4. fibrous layer of mediastinal parietal pleura
5. serous layer of parietal mediastinal pleura

Discuss the anatomy of the knee joint. Include bones, cartilage, ligaments, muscles, bursa, vascular supply, innervation, stabilization, center of gravity, and locking/unlocking of the knee joint. (12 pts)

Bones and Articulations

• Synovial hinge joint between the femoral and tibial condyles.
• Tibial plateau is cupped by the medial and lateral menisci.
• Femoral condyles
• Patella articulates anteriorly as a sesamoid bone in the quadriceps tendon.

ligaments

• Medial collateral ligament (attached to medial meniscus).
  • medial femoral epicondyle to the medial tibial condyle.
  • resists abduction of tibia.
• Lateral collateral ligament (interval between lateral meniscus and ligament transmits popliteus m.
  • From lateral femoral epicondyle to the head of the fibula
  • resists adduction of tibia.
• Anterior cruciate ligament
  • from lateral posterior femoral condyle to anterior aspect of tibial intercondyler eminence.
  • resists forward displacement of the tibia.
• Posterior cruciate ligament.
  • from posterior medial femoral condyle to posterior aspect of tibial intercondyler eminence.
  • resists posterior displacement of tibia.
• Oblique popliteal and arcuate ligaments strengthen the posterior joint capsule.
• coronary, transverse genicular, and meniscofemoral ligaments secure the menisci.

Cavities and bursae

• Synovial joint cavity
  • attaches to edges of menisci - articular surface is intrasynovial
  • Alar folds anterior to anterior crucial ligament - posterior limit of midsaggital synovial cavity
  • reflections of the synovial membrane along the intercondylar fossa - cruciate ligaments are extrasynovial.
  • continuous with suprapatellar bursa (quadriceps bursa)
• prepatellar bursa
• infrapatellar bursa

Capsular joint cavity

• ligaments making up the capsule (above)
• intercondylar area is extrasynovial
• popliteus tendon within cavity

Muscles, Movements and limitations of movement

• Primarily flexion and extension (hinge joint).
• Some rotation (30-40 degrees) is possible when the knee is flexed.
• Flexion is primarily by the hamstrings, short head of biceps, gracilis, and sartorius.
  • innervated by tibial portion sciatic, peroneal portion sciatic, obturator, and femoral nerves respectively.
  • minor flexion by popliteus, gastrocnemius, and plantaris.
  • flexion is limited by quadriceps, cruciate ligaments, and by opposing soft tissues (calf and thigh).
• Extension is primarily by the quadriceps and tensor fascia lata.
  • innervation by femoral nerve and superior gluteal nerve.
  • extension is limited by hamstrings, cruciate ligaments, collateral ligaments, posterior joint capsule.
• Medial rotation of tibia is primarily by popliteus, semitendonosus, gracilis, and sartorius.
  • innervation by tibial nerve, tibial portion sciatic, obturator, and femoral nerves respectively.
  • limitation of movement by collateral ligaments
• Lateral rotation of tibia is primarily by biceps femoris.
  • innervation by tibial and peroneal portions of sciatic nerve.
• limitation of movements by collateral ligaments.
  • Abduction and adduction is limited by the medial and lateral collateral ligaments.

Fascial Specializatons

• patellar retinaculum
• iliotibial tract
• investing fascia

vascular supply

• Genicular anastomosis
  • Superior and inferior, medial and lateral genicular arteries, and middle genicular from the popliteal artery.
  • descending genicular artery from femoral artery and descending branch from lateral femoral circumflex artery
  • Fibular circumflex artery, and anterior and posterior tibial recurrent arteries from the anterior and posterior tibial artery
  • Accompanying veins

Innervation (Hilton's Law)

• small branches of the femoral, obturator, and sciatic, and tibial nerves pierce the joint capsule.

"Screw Home"

• Consider when the knee is extended with the foot planted on the ground. In this case, the tibia is fixed by virtue of the planted foot. Thus, rotation of the knee occurs as movement of the femur. The femur rotates medially as the knee "locks" in extension. The lateral femoral condyle is smaller than the medial femoral condyle. As the knee is extended the smaller condyle moves through its arc before the medial condyle. Thus, movement stops at the lateral condyle while the femoral medial condyle continues to move further posteriorly. This movement results in a medial rotation of the femur.
• This medial rotation torques the joint capsule and it's ligamentus specializations (medial and later collateral ligs). The "twisting" of the capsular ligaments causes the region to tighten. This firmly approximates the femoral condyles to the tibial plateau and "locks" the knee. The femur "screws" medially onto the tibial plateau due to the larger medial condyle and the twisting of the capsular ligaments. On extension, the knee goes through a "screw home" rotation that results in "close packing."
• The final medial rotation of the femur is driven by the line of gravity moving anterior to the axis of the knee joint. Thus, locking the knee is driven by gravity. Unlocking the knee requires muscular involvement. The popliteus, having lateral superior to medial inferior attachments, posterior to the axis of the knee, can to lateral rotate the femur (reverse origin and insertion) and, thus, unlock the knee joint.