Lungs and Anterior/Middle Mediastinum - A Partial Study Guide

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Overview

Lungs diagram

• trachea bifurcation at T4
• right bronchus - shorter, wider, longer, - site for foreign objects
• left bronchus - 2X longer than right, more transverse
• carbon may replace alveoli
• left lung displaced by heart
• left lung has two lobes plus lingula
• right lung has three lobes
• apex is convex, base is concave
• costal margins
• impressions of ribs
• mediastinal portion - heart, esophagus, trachea
• fissures - oblique on both lungs at T3 back, 5th rib mid-axillary, 6th rib anteriorly
• hoizontal fissure of right lung - follows 4 rib
• middle lobe of right lung, not on the left
• lingula thought to represent middle lobe of left lung

Mediastinal surfaces

• root of the lung - anterior: arteries, inferior: veins, posterior: bronchi*
• eparterial bronchus of right lung
• right lung impressions
  • esophagus
• impressions of the left lung
  • aorta

bronchiopulmonary segments

• 400 million alveoli
• parts of bronchopulmonary segment
  1. 3rd order bronchus
  2. pulmonary artery
  3. lung tissue

Vasculature

• bronchial aa - two on the left and one on the right
  • left from the aorta and right from posterior intercostal

Mechanics of breathing

• inspiration and expiration
• expiration is recoil
• bell jar example - negative pressure inflates lung
• expansion by diaphragm and ribs
• capillary example of two panes of glass - surface tension
• upper 7 ribs - pump handle, anterior/posterior movement
• lower 5 ribs - bucket handle, transverse movement
• diaphragm - vertical movement
• barrel chested child - diaphragmatic breathing
• pregnancy - thoracic cage breathing
• many muscles involved in forced inspiration and expiration

Questions for the Lungs and Anterior/Middle Mediastinum

1. The trachea bifurcates into secondary main bronchi on the posterior surface of the second thoracic vertebra.
2. The right main bronchus is more vertical than the left main bronchus owing to the positioning of the heart.
3. The oblique fissure of the right lung has surface projections to T3 T5 6th rib.
4. The horizontal fissure of the right lung has surface projections to T4 and to rib 4.
5. In general, the A/P topography is artery, vein, bronchi for the lungs.
6. Cradled by the leaflets of the pulmonary ligament at the inferior extent is a pulmonary vein.
7. The arch of the azygos vein is impressed upon the left lung.
8. Primary bronchi define the bronchopulmonary segments.
9. The second order bronchus, pulmonary vein, and lung tissue define a bronchopulmonary segment.
10. The bronchial arteries carry deoxygenated blood to the lungs.
11. The pulmonary veins carry deoxygenated blood to the right atrium of the heart.
12. The lungs are said to follow expansion of the thoracic wall by the properties of surface tension.
13. Air rushing into the thoracic cavity, but not the pleural cavity, leads to pneumothorax.
14. The costotranverse joints of the upper ribs are cup shaped and the constotransverse joints of the lower ribs are p lanar.
15. The true ribs articulate DIRECTLY with the sternum.
16. The movement of the upper six ribs is similar to the movements of a pump handle with the sternum being the pump handle.
17. During inspiration the lower ribs slide laterally at the costotransverse joint.
18. The vertical movement of thoracic expansion is mediated by the diaphragm.
19. The vertical movement of thoracic expansion is limited by pregnancy.
20. A costovertebral joint includes two vertebral bodies, an intervertebral disc, and the head of a rib.
21. The costochondral joint is fibrous and the sternochondral joint is synovial.
22. The lingula is a tongue like projection of the upper lobe of the right lung that lies immediately deep to the sternochondral joint of the right 6th rib.

True/False - August 18, 2010

1. The level of the T4 vertebra marks the location of the tracheal bifurcation.
2. The deviation of the heart to left side provides a mneumonic for knowing that the left bronchus is longer and more transverse than the right bronchus.
3. The horizontal fissure is unique to the left lung.
4. The lingula provides the inferior border of the cardiac notch.
5. Posteriorly, the oblique fissure is at the level of T3 vertebra, mid-axillary at 5th rib, mid-clavicular at 6th rib.
6. Horizontal fissure marks the 7th rib.
7. The hilum of the lung is cradles by the suprapleural membrane.
8. The pulmonary ligament is formed by pleural reflections beginning at the hilum of the lung and extending inferior toward the diaphragmatic surface.
9. The segmental bronchi are known as tertiary bronchi.
10. Each bronchopulmonary segment has a segmental pulmonary artery and a lobar bronchus.
11. Lung tissue proper is not perfused by either the pulmonary artery or vein.
12. The upper 7 ribs mediate an increase in the anterior/posterior dimension of the thorax on inspiration.
13. The lower 5 ribs mediate an increase in the transverse dimension of the thorax on inspiration.
14. The pump handle movement of respiration refers the movements of the sternum whereas the bucket handle movement refers to movements of the costal margin.
15. The vertical dimension of the thorax increases when the diaphragm contracts.
16. The costotransverse joints allow rotation (cup shaped) for the upper 7 ribs and sliding (planar) for the lower 5 ribs.
17. The costochondral and sternochondral joints participate in the movements of respiration.
18. The lungs receive oxygenated blood from the pulmonary arteries
19. Relaxed breathing is primarily mediated by the upper 7 ribs.
20. Cup shaped articulations of the costotransverse joint permit transverse movement of the lower ribs.
21. The arterial supply to the left lung is derived directly from the aortic arch

Definition and Short Answer

1. Contrast the anatomy of the pulmonary arteries and veins in regard to a bronchopulmonary segment
2. The anterior and posterior lamina of the pulmonary ligament (a visceral ligament) diverge superiorly near the (blank) of the lung. At this location the anterior and posterior lamina of the pulmonary ligament reliably embrace a (blank). This relation can be used to unequivocably identify a (blank) and, thus, judge differences in wall thicknesses between (blank) and (blank). In general, structures easily observed at the root of the lung from anterior to posterior, are the (blank), (blank), and (blank).
3. The left phrenic nerve enters the thoracic inlet crossing the anterior surface of the (blank) artery and the posterior surface of the (blank) vein (Grants 1.44). The phrenic nerve descends through the (blank) fascia of the (blank) mediastinum passing (blank) to the root of the lung. As the phrenic nerve travels along the mediastinum the fascia immediately medial to it is the (blank) fascia and the fascia immediately lateral to it is the (blank) fascia.
4. The costotransversal joints have (blank) shaped articulations at the transverse process for the upper 7 ribs. These articulations allow upward (blank) at the neck of the rib during (blank). The costotransverse joints have (blank) shaped articulations at the transverse process for the lower 5 ribs. These articulations allow outward (blank) at the neck of the rib during (blank).
5. Visible impessions of the left lung include the (blank) of the aorta whereas visible impessions of the right lung includes (blank) of the azygos vein.
6. It can be argued that the poor esophagus is "bullied" about through out its course through the thorax. The (blank) of the trachea at the (blank) of the (blank) lung is said to force the esophagus to a (blank) position and possibly restrict the flow of contents. The aorta is said to force the esophagus to remain to the (blank) of the midline of the anterior vertebral bodies and thus, deny the esophagus any social interactions with the (blank) lung. Nearing the inferior aspect of the thorax the esophagus, fed up with being pushed around, deviates to the left and leaves a positive impression on its new found friend -- the (blank) lung.

Essay

1. How is the pulmonary ligament similar to the venous mesocardium? Consider function and anatomy.
2. What left lung impressions are most noticeably differ from the right? Is there any anatomical significance to the lingula?
3. Could a stab wound penetrating into the thoracic cavity from the anterior chest wall do so without creating pneumothorax? If so, exactly where might this wound occur? Is there clinical significance to this?
4. Contrast the relations (6 directions) of the pulmonary ligaments for the left and right lung.
5. Where might you find two layers of serous parietal pleura in contact with each other?

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