THE THORAX AND THORACIC VISCERA. 77 



Intercostal nerves, 843-5. ( 82 3~5~ 6 ) 

 Upper group. Lower group. 

 First thoracic nerve. 

 Upper intercostal nerves. 



Lateral cutaneous nerves of the thorax. 



Anterior cutaneous nerves of the thorax. 

 Lower intercostal nerves. 



Branches. 



Expose and trace the intercostal arteries in two or three of the intercostal spaces, as the third, fifth, and 

 seventh. In the anterior portion of the upper intercostal spaces, expose the internal mammary and 

 anterior intercoslal arteries. 



Superior intercostal artery, 550. (540-1) 



Aortic intercostal arteries, subcostal artery, 581-2. (570-1) 



The intercostal portion. 



Collateral intercostal branch. 

 Internal mammary artery, 5489-50. (5389-40) 



Thoracic portion : 



Anterior intercostal arteries. 

 Perforating, or anterior perforating branches. 

 Intercostal veins, subcostal, 644-5. (632) 

 Internal mammary veins, 640. (628) 

 Intercostal lymphatics, 696. (681) 

 Internal mammary, sternal, or anterior intercostal glands, 696. (68 1) 



Remove the intercostal muscles from the anterior portion of the upper five intercostal spaces, exposing 

 the outer surface of the parietal pleura. With the finger carefully separate the pleura from the anterior 

 portion of the second, third, fourth, and fifth ribs and their costal cartilages, on each side ; also from the 

 intervening portion of the sternum. Divide the second, third, fourth, and fifth ribs at the axillary line. 

 I )ivide the sternum transversely below the cartilages of the first ribs, also just above the cartilages of the 

 sixth ribs. Beginning above, raise the sternum with its attached cartilages and ribs, drawing it forward and 

 downward, carefully separating the pleura and internal mammary arteries from it. With a chain hook 

 retain it at a right angle with the thoracic wall while the triangularis sterni is exposed, then remove it. 



Triangularis sterni, 421-2 ; Fig. 301. (418-19) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. 



Divide the pleura by a vertical incision about six inches from the median line, and by incisions parallel 

 with the second and sixth ribs, to within about three inches of the median line. The flap thus formed 

 can be turned forward, and the reflection of the pleura can be readily demonstrated, also the interval 

 of non-approximation of the pleural sacs. The visceral and parietal portions of the pleura should then 

 be traced and the relations studied. 



The pleurae, 958-60. (936-8-9) 



Visceral layer, or pleura pulmonalis. 

 Parietal layer, or pleura costalis. 

 Ligamentum latum pulmonalis. 

 Right pleural sac. 

 Inner surface. 

 Outer surface. 

 Viscera within the thoracic cavity, 936. (915) 



Heart. Lungs. 



Mediastinal space, 936-7-8. (915-16-17) 

 Superior mediastinum. 

 Anterior. Posterior. 

 Middle mediastinum. 

 Superior mediastinum : 

 Boundaries : In front. 

 Behind. 

 On each side. 

 Above. 

 Below. 



Middle mediastinum. 

 Anterior mediastinum. 

 Posterior mediastinum. 



