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).

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.

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