Re: Lungs

Comments:
: : Lungs : : 1. At what vertebral level does the trachea bifurcate? : The trachea bifurcate at T4. The ridge intervening between the two primary bronchi is called the carina. : : 2. Discuss the characteristics of the right and left bronchus. Which bronchus is most likely to receive foreign objects - why? : The right bronchus is shorter, wider, and more vertical than the left. (I've been thinking of the bifurcation like an upside down "V," where the V is tipped slightly laterally away from midline. A line bisecting it superior-inferior doesn't leave two equal angles.) Since the right bronchus is more vertical, foreign objects are more likely to drop into it, rather than make the sharper turn into the left bronchus. : : 3. What is the cardiac notch? Why is this notch important in gaining access to the pericardial cavity without causing a pneumothorax? : The cardiac notch is an area on the medial anterior border of the left lung where the pericardium is immediately deep to the thoracic wall. This is a great spot to do pericardiocentesis since you can insert a needle from the anterior aspect without putting a hole in the pleural cavity. : : 4. Discuss the oblique fissure of the lung. : The oblique fissure separates the inferior lobe from the middle lobe in the right lung and inferior from superior in the left lung. It wraps around from the T2 on the posterior side to about the 6th rib on the medial anterior side. : : 5. Discuss the horizontal fissure of the lung. : The horizontal fissure, present only the in right lung, separates the upper from the middle lobe. It wraps around the anterior of the lung, from an intersection with the oblique fissure laterally to about the 4th costal cartilage. : : 6. Discuss surrounding structures of the lung that leave an impression in the cadaver. : Assuming they're preserved perfectly, the right lung has three grooves extending posterior-superior above the eparterial bronchus - from medial to lateral they're caused by the brachiocephalic vein, trachea, and esophagus. There can be smaller notches near the superior anterior border for the first rib and subclavian artery. A groove for the azygous vein can be seen running horizontally above the hilum, and a groove for the esophagus can be seen running superior-inferior laterally to the hilum. The cardiac impression indents both the right and left lungs inferior-medial to the hilum. In the left lung, the aortic arch leaves a deep impression superior and lateral to the hilum; superior-inferior grooves above the hilum for the brachiocephalic vein and subclavian artery can also be seen. : : 7. What is the relationship of the bronchus, artery, and vein at the hilum of the right, and the left, lung. : In the right lung, the bronchus is superior, the artery is medial, and the veins are inferior. In the left lung, the artery is superior, the bronchus is lateral, and the veins are inferior. : : 8. What is the eparterial bronchus? : The primary bronchus in the right lung that is superior to the pulmonary artery. : : 9. What is a bronchopulmonary segment and why is it important? : : 10. Discuss the drainage of the pulmonary veins. : : 11. Discuss the difference between the pulmonary vasculature and the bronchial vasculature. : : 12. Discuss the mechanisms of respiration - especially about the visceral and parietal pleura. : : 13. Define three axes of movement of the thorax. : : 14. What muscle(s) is(are) responsible for quiet inspiration? : : 15. What muscle(s) is(are) responsible for quiet expiration?

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