458 APPENDIX. 



{a) The anterior thoracic was probably cut in dissecting the 

 pectoral muscles; it may be found, but its distal end is probably 

 cut off. 



{b) The long thoracic is easily followed, 



(c) The subscapular. Follow the main artery before dissecting 

 its branches. Where the subscapular disappears between the long 

 head of the triceps, the latissimus dorsi, and the scapula, it may be 

 traced and found again as follows: Remove the skin from the outer 

 side of the shoulder, — taking great pains to remove otily the skin and 

 not to injure the vena cephalica (p. 319), a large vein that lies just 

 beneath the skin on the lateral surface of the shoulder, coming from 

 the elbow. The branches of the subscapular will be found appearing 

 on the lateral surface of the arm in the angle between the spino- 

 trapezius, the long head of the triceps, and the infraspinatus. The 

 distal branches may then be followed. 



{d) The posterior circumflex (p. 296) may be traced distad in a 

 similar manner, by seeking it beneath the caudal border of the 

 spinotrajiezius. (Do not injure the vena cephalica.) 



(e) The other branches of the brachial artery and vein present no 

 difificulty till we come to the coUateralis radialis superior (Fig. 122, .v). 

 This must be traced with great care, along with the vena mediana 

 cubiti (p. 319, and Fig. 122, y). Remove the skin from the e.xtensor 

 side of the forearm, taking great pains not to remove anything more 

 than the skin. The artery and vein lie beneath the skin and should 

 be tracetl to the hand (see Fig. 130). 



Along with the collateral radial artery trace the vena cephalica 

 (p. 319, and Fig. 130, a and c). Follow it across the shoulder, 

 noting the brancli to the posterior circumflex vein. 



The remainder of the blood-vessels of the arm present no special 

 difficulty (see Figs. 123 and 124), 



Make a diagram of the subclavian artery, as far as dissected. 



III. Remove the skin from the sides of the neck, exposing the 

 sternomastoid muscles and the external jugular veins crossing them 

 (see Fig. 131). Clean the surface of the sternomastoid muscles, 

 without injuring the vein; separate the two muscles caudad, and cut 

 each close to the attachment to the sternum. Find the sternohyoid 

 and sternothyroid muscles, and cut them close to their attachment 

 to the first rib. Uncover the right side of the thorax m the same 

 way as the left, cut the ribs without injury to the nerves and vessels 

 of the right axilla, cut the internal mammary artery and vein (after 

 tying the latter), and thus remove the sternum with nearly the entire 

 thoracic wall. 



The blood-vessels of the thorax may now be more completely 

 exposed, (If the nerves are to be dissected on the same specimen, 

 find the phrenic, vagus, and sympathetic nerves (Fig. 157), and take 

 the greatest pains not to injure them.) 



I. The coronary arteries and the veins of the heart (pp. 281 and 

 316). 



