I3IO 



HUMAN ANATOMY. 



the branches to the long and inner heads of the triceps. It passes backward, posterior to the 

 intercosto-humeral nerve, and after piercing the deep fascia, spreads out to be distributed to the 

 integument over the inner head of the triceps to within a short distance of the elbow (Fig. iioi). 

 It is accompanied by a small artery. 



The superior external cutaneous branch (n. cutaneus brachii posterior) (Fig. iioi) arises 

 from the musculo-spiral posterior to the external intermuscular septum and pierces the deep 

 fascia below the middle of the arm, between the external head of the triceps and the brachialis 

 amicus. It passes down with the cephalic vein and is distributed to the integument of the 

 external anterior portion of the arm down to or slightly below the elbow. 



The inferior external cutaneous branch (n. cutaneus antebrachii dorsalis) (Fig. 1102) arises 

 and becomes superficial similarly to and in common with the superior. After passing down the 



Fig. 



IIOI. 



"Cutaneous branches of circumflex nerve 



Brancii of intercosto- ' 

 humeral nerve 



Int. cutaneous branch of mus- 

 culo-spiral nerve 



Lesser internal cutaneous, 

 joined below the leader by 

 branch of intercosto-hu- 

 meral nerve 



Sup. ext. cutaneous branch of mus- 

 culo-spiral nerve 



Inf. ext. cutaneous branch of mus- 

 culo-spiral nerve 



Post, cutaneous 

 branch of musculo- 

 cutaneous nerve 



From post, branch of internal cutaneous nerve 



Superficial dissection of right arm, showing cutaneous nerves of posterior surface. 



arm it enters the forearm by crossing the dense fascia stretched between the olecranon and the 

 internal condyle of the humerus. From this point it continues its downward course along the 

 posterior aspect of the forearm as far down as the wrist or even onto the dorsum of the hand. 

 It is distributed to the skin of the posterior portion of the arm between the areas supplied by 

 the other cutaneous branches of the musculo-spiral and to that part of the posterior aspect of 

 the forearm between the portions supplied by the posterior branch of the internal cutaneous 

 and the posterior branch of the musculo-cutaneous. In the neighborhood of the wrist it inos- 

 culates with the musculo-cutaneous and sometimes with the branch to the dorsum of the hand 

 from the ulnar. 



(J.'The muscular branches (rr. musculares) are given off {aa) before the musculo-spiral 

 enters the musculo-spiral groove and {i>b) after leaving the groove. 



aa. Before entering the groove branches arise for the supply of the three heads of the 

 triceps and the anconeus. 



