Introduction to Thorax - A Partial Study Guide

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Anterior Chest Wall

• know lymphatic drainage of the breast
• pectoralis major and minor

Thoracic cage drawing

• clavicle in clavicular notch
• first rib at sternum
• thoracic inlet - manubrium, first rib, T12 vertebral body, jugular notch
• thoracic outlet -
• sternum - manubrium, body, xiphoid process
• angle of Louis - marks 2nd rib, sternal angle, bend between manubrium and body, rib counting
• projections
  • sternal angle - T4 body
  • jugular notch - T2/3 body
  • xiphysternal junction - T9/10
  • costal margin ribs 7-10 - L3
• external intercostal membrane - located anterior, fiber direction superior lateral to inferior medial (reverse direction at posterior wall, but simply physics)
  • part of external intercostal muscles, EIM begins at costochondral junction and proceeds posterior
• internal intercostal membrane - located posterior, from vertebral body to near angle of the rib. * internal intercostal muscle - nearly opposite fiber direction of the external incostal, orthogonal
• subcostal muscle - span a rib posterior, innermost layer, continuous with innermost intercostal
• innermost intercostal
• transversus thoracis
• VAN is set by the angle of the rib, located at the costal groove (inferior margin of rib
• muscle layers at mid-axillary line
  1. external intercostal mm
  2. internal intercostal mm
  3. innermost intercostal mm
  • VAN is located at the costal groove deep to internal intercostals and superficial to innermost intercostal mm
• intenal thoracic artery and vein
  • venae commitantes
  • artery is a branch of the subclavian artery
  • divide into superior epigastric and musculophrenic arteries, "phrenic" is a reference to the diaphragm
• ribs
  • 1-7 true, direct
  • 8-10 false
  • 11-12 floating

Thoracic cavity

• plurae, lungs, mediastinum
• visceral pleura
• parietal pleura
• pleural cavity - defined by the inner walls of the pleura
• endothoracic fascia "glues" the parietal pleura to the inner body wall, parietal pleura can be dissected away from the wall
• visceral pleura is directly applied to the viscera and is generally not dissectable away

Hand and finger metaphore for pleura

• Simpson's fascia - extends superior to clavicle, endothoracic fascia
• cupula of pleura - adhered to Simpson's fascia
• diaphragmatic pleura
• costal pleura
• mediastinal pleura
• parietal pleura has two layers - fibrous and serous
• visceral pleura has one layer - serous or mesothelial layer
• What holds the visceral pleura immediately adjacent to parietal pleura?
• costodiaphragmatic recess - ics 8, pleural tap, redundancy of costal and diaphragmatic pleura

Frontal section of the thoracic wall near mid-axillary line

• layers of the thoracic wall
  1. epidermis
  2. dermis
  3. tela subcutanea
  4. external intercostal m (investing fascia)
  5. internal intercostal m
     • VAN - inferior margin of rib, costal groove
  6. innermost intercostal m
  7. endothoracic fascia
  8. fibrous layer parietal pleura
  9. serous layer of parietal pleura
     • costodiaphragmatic recess of pleural cavity
  10. serious layer of diaphragmatic pleura
  11. fibrous layer of diaphragmatic pleura
  12. endothoracic fascia (of diaphragm)
  13. diaphragm
  14. transversalis fascia
  15. extraperitoneal connective tissue
  16. fibrous layer parietal peritoneum
  17. serous layer parietal peritoneum
  18. peritoneal cavity
  19. viseral peritoneum of liver on the right and of the spleen on the left
  20. liver on right and spleen on left

Sagittal drawing of mediastinum

• Boundaries of superior mediastinum
  • superior: jugular notch to T1
  • inferior: angle of Louie to T4
• boundaries of inferior mediastinum
  • superior: superior mediastinum as defined above
  • inferior: diaphragm
• boundaries of anterior mediastinum
  • superior: super mediastinum
  • inferior: diaphragm
  • posterior: pericardial sac anterior surface
  • anterior: posterior wall of sternum
• boundaries of posterior mediastinum
  • from inferior wall of pericardial sac (anterior) to angle of rib (posterior)
• boundaries of the middle mediastinum
  • superior: superior mediastinum, sternal angle to T4
  • inferior: diaphragm central tendon
  • anterior: anterior mediastinum, anterior surface of pericardial sac
  • posterior: posterior surface of pericardial sac, anterior extent of posterior mediastinum
  • lateral: pleural cavity (mediastinal parietal pleura)

Questions for the Introduction to Thorax

True/False - August 16, 2011

1. The lactiferous ducts are a specialization of cutis retinacula.
2. The anterior thoracic artery is applied to the posterior surface of the brachiocephalic vein.
3. The first rib and the clavicle both articulate with the xiphoid process.
4. The jugular notch defines, in part, the thoracic outlet.
5. The body of the sternum, on an A/P projection, is superimposed on the the apex of the heart.
6. The jugular notch is at the A/P projection to T4.
7. The costal margin consists of cartilage that articulates with the distal ends of rib 7-10.
8. The most inferior extent of the costal margin is at the same S/I level as the third lumbar vertebra.
9. The fiber direction of the external intercostal membrane is from superior/lateral to inferior/medial.
10. The fiber direction of the internal intercostal muscle at the chondral cartilages is superior/medial to inferior/lateral.
11. The deep surface of the innermost intercostal muscles are lined by endothoracic fascia.
12. Despite blockage of the aorta at the ligamentum arteriosum (coarctation), blood continues to flow in the descending aorta.
13. Posterior intercostal arteries arise from the internal intercostal artery.
14. Anterior intercostal arteries arise from the ascending aorta.
15. The collateral circulation of the thoracic wall defines an arterial shunt across the thoracic descending aorta.
16. The hilum of the lung is a point of invagination "into" the pleural cavity.
17. The lung is located in the thoracic cavity, but not in the pleural cavity.
18. Endothoracic fascia provides adherence of the diaphragmatic parietal pleura to the suprapleural membrane.
19. The mesothelial layer of parietal pleura faces into the pleural cavity.
20. The visceral layer of pleura has a mesothelial layer, but not a fibrous layer.
21. A pneumothorax happens when the endothoracic fails to secure the visceral pleura to the thoracic wall.
22. The parietal pleura becomes redundant at the costodiaphragmatic recess.
23. The subcostal muscles define, in part, the inner (deep) surface of the neurovascular plane for the intercostal vessels and nerves.
24. The posterior intercostal veins drain directly into the inferior vena cava.
25. The subcostal muscles, innermost intercostal muscles, and transversus thoracis muscles define the deep wall of the neurovascular plane.
26. The internal intercostal muscle defines the superficial wall of the neurovascular plane.
27. False ribs connect directly to the xiphoid process..
28. Costochondral joints are syndesmoses and sternochondral joints are synovial.
29. Intervening between the left and right pleural cavities is the mediastinum.
30. The costomediastinal recess defines a location where paracentesis (access to the pericardial sac with a hypodermic needle) avoids puncturing the pleural cavity.
31. The A/P projection from the sternal angle to the L4 vertebra defines the inferior boundary of the superior mediastinum.
32. A projection from the sternal angle to the T1 vertebra defines the superior boundary of the superior mediastinum.

True/False - August 17, 2010

1. The lactiferous ducts are 15-20 in number for both the male and the female.
2. Retinacula cutis is a differentiated part of the tela subcutanea that provides support to the female breast.
3. The right and left internal thoracic arteries are from the right and left subclavian arteries.
4. The jugular notch is part of the manubrium.
5. Intervening between the right and left clavicular notches is the jugular notch.
6. The manubrium refers to a shield whereas the xiphoid process refers to a sword.
7. The jugular notch, in part, defines the thoracic outlet.
8. The sternal angle is formed, in part, by the inferior extent of the manubrium.
9. The costochondral cartilage connects the ribs to the vertebral bodies.
10. The external intercostal membrane is located superficial to the external intercostal muscle.
11. The lateral extent of the external intercostal membrane is at the costochondral joint.
12. The internal intercostal membrane lies deep to the innermost intercostal membrane.
13. The subcostal muscles located on the anterior thoracic wall and the transversus thoracis muscles located on the posterior thoracic wall span a rib.
14. The intercostal vein, artery, and nerve lie along a groove at the superior border of a rib.
15. The upper anterior intercostal spaces have anterior intercostal arteries from the internal thoracic artery.
16. The subcostal muscles are observed in the paravertebral region of the thoracic wall; the internal intercostal muscles are observed at the midaxillary line; and the transversus thoracis muscles are observed in the parasternal region.
17. The contents of the pleura cavities include the lungs.
18. The contents of the pleural cavities, under non-pathological conditions, include a film of pleural fluid.
19. The parietal pleura has a single mesothelial cell layer.
20. The visceral pleura has both a mesothelial cell layer and a fibrous layer.
21. The endothoracic fascia "glues" the visceral pleura to the lung.
22. The mediastinum separates the thoracic cavity from the abdominal cavity.
23. The pulmonary ligament is known as a visceral ligament and consists of a reflection of visceral pleura.
24. Simpson's fascia (suprapleural membrane) is a thickening of visceral pleural at the apex of the lung.
25. A reflection of costal parietal pleura to become diaphragmatic parietal pleura defines, in part, the infer extent of the costodiaphragmatic recess.
26. The pleural cavity, under non-pathological conditions, is at negative atmospheric pressure.
27. An equalization of pleural cavity pressure and atmospheric pressure causes the lung to collapse - pneumothorax.
28. A needle that passes through the costodiaphragmatic recess will penetrate costal parietal pleura to enter the recess and then diaphragmatic parietal pleura to leave the recess.
29. A needle that passes through the pleural cavity along the midaxillary line at the 4th intercostal space will pierce costal parietal pleura to enter the pleural cavity and visceral pleura to leave the pleura cavity.
30. The mediastinum is a partition that separates the two pleural cavities.

Definition and Short Answer

1. The deepest layer of intercostal muslces is represented by the __________ muscles anteriorly, the ________ muscles at the midaxillary line, and the ________ muscles posteriorly.
2. Which of the following questions is a nightmare?. 1) Discuss the contents of the thoracic cavity. 2) Discuss the contents of the pleural cavity.
3. The endothoracic fascia is immediately applied to what layer of pleura?
4. What is the pulmonary ligament. Is there a fibrous layer of this ligament?
5. The internal thoracic arteries branch from the (blank) arteries. The left of these arteries is a branch of the (blank) artery whereas the right of these arteries is a branch of the (blank) artery. There is a conditional known as coarctation of the aorta. The aorta becomes occluded at a location distal to the parent arteries of the internal thoracic arteries and proximal to the branching of the posterior intercostal arteries. Thus, there is blood flow in the normal direction within the internal thoracic arteries. Despite near total occlusion of the aorta proximal to the branching of the posterior intercostals from the descending aorta, the descending aorta fills with blood and there is blood flow to the entire body. Explain the pattern of blood flow in the case of coarctation of the aorta. Where is the normal direction of flow reversed? Where is blood pressure apt to be elevated and where is it apt to be lowered? What radiographic findings are expected? What might you hear, to your initialize surprise, when attempting to listen to he heart with a stethoscope?
6. The heart position causes the left anterior costomediastinal pleural reflection to deviate to the left side. This provides the opportunity to perform pericardiocentesis without entering either pleural cavity. Thus, a needle is passed through the fatty contents of the (blank) ligament. Provide a brief account of the procedure.
7. A pleural tap of the costodiaphragmatic recess requires that a needle through the (blank) intercostal space at the (blank) line. The fascial barriers penetrated are: 1) skin, 2) (blank), 3) investing fascia, 4) (blank), 5) (blank), 6) (blank), 7) endothoracic fascia, 8) (blank), 9) (blank), 10) pleural cavity. If the needle continued through the pleural cavity on the right side the next fascial barrier would be: 11) visceral layer of (blank), 12) blank, 13) (blank), 14) diaphragm.
8. The intercostobrachial nerve is derived from the (blank) cutaneous branch of the (blank) ramus of the (blank) spinal nerve. The left intercostobrachial nerve is of great clinical importance. Be prepared to briefly discuss "referred pain" along the distribution of the left intercostobrachial nerve.
9. The cutaneous innervation of the skin overlying the xiphoid process is provided by the medial branch of the (blank) cutaneous nerve derived from the (blank) intercostal nerve. The vertebral projection of the xiphoid process projects to the (blank) thoracic vertebrae. The (blank) rib articulates at the xiphisternal junction.
10. The internal thoracic vessels are secured to the posterior surface of the anterior thoracic wall. These vessels lie immediately posterior (deep) to the (blank) muscles and immediately anterior (superficial) to the (blank) muscles. Are the internal thoracic vessels within the same neurovascular plane as the intercostal vessels? Explain?
11. The innermost intercostal fascial plane has been described as representing three muscles. The (blank) muscles anterior; the (blank) muscles are intermediate (mid-axillary); the (blank) muscles are posterior.
12. The thorax is to the pleural cavity as the capsule of the knee joint is to the _____.

Essay

1. Collateral circulation of the thoracic cage. Discuss the flow of blood in the case of coarctation of the aorta. Where is blood flow reversed from normal.
2. What fascial planes are penetrated by wound that begins at the right mid-axilary line at the eighth intercostal space and proceeds into the liver.
3. Pleurisy may cause adhesions that, in turn, lead to newly formed lymph channels. How might these channels be different from the typical lymphatic drainage of the lungs?
4. A stab wound penetrates straight into the right side of the thorax in the mid-axillary line at the 8th intercostal space. What are the facial layers and spaces are penetrated? Limit your answer to structures of the thorax.
5. What bony landmark would be useful to identify the terminal branching of the internal thoracic artery? What are the distributions of these terminal branches?
6. What relation could you rely upon to unequivocably identify the internal intercostal muscle from a posterior view of the anterior chest wall?
7. What relations could you rely upon to unequivocalbly ID the transversus thoracis from an anterior view?
8. What nerve branches provide innervation to the skin overlying the xiphoid process? These nerves are derived from what spinal nerve. What is the vertebral projection of the xiphoid process?
9. Discuss the boundaries of the visceral and parietal pleura. Provide approximate vertebral levels in defining the boundaries.

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