708 



THE NEKVOUS SYSTEM. 



Nerve to teres minor 

 Axillary nerve 



Branches to deltoid 



Lateral cutaneous 

 nerve of the arm 



Nerve to long 

 head of triceps 



NERVUS ULNARIS. 



The ulnar nerve arises from the medial cord of the brachial plexus, from 

 the eighth cervical and first thoracic nerves. It also occasionally has a root from 



the lateral cord of the 

 plexus (seventh cervical 

 nerve). In the axilla it 

 lies between the axillary 

 artery and vein, and behind 



^^gg^g55^^3j|gj^ the medial cutaneous nerve 



of the forearm (O.T. in- 

 ternal cutaneous); in the 

 proximal half of the arm 

 it lies on the medial side 

 of the brachial artery 

 anterior to the triceps 

 muscle. In the distal 

 half of the arm it is separ- 

 ated from the brachial 

 artery ; and passing behind 

 the intermuscular septum, 

 and in front of the medial 

 head of the triceps in com- 

 pany with the superior 

 ulnar collateral (O.T. in- 

 ferior profunda) artery, it 

 reaches the interval be- 

 tween the medial epicon- 

 dyle of the humerus and 

 the olecranon. It is there 

 protected by an arch of 

 deep fascia stretching be- 

 tween the epicondyle and 

 the olecranon. It enters 

 the forearm between the 

 humeral and ulnar origins 

 of the flexor carpi ulnaris, 

 and courses distally be- 

 tween the flexor carpi 

 ulnaris and flexor digi- 

 torum profundus. In the 

 distal half of the forearm 

 it becomes comparatively 

 superficial, lying on the 

 medial side of the ulnar 

 artery, overlapped by the 

 tendon of the flexor carpi 

 ulnaris. Just proximal to 

 the transverse carpal liga- 

 ment, and lateral to the 

 pisiform bone, it pierces the 

 deep fascia, in company 

 with the artery, and passes 

 into the hand over the 

 transverse carpal ligament. Reaching the palm it divides, under cover of thej 

 palmaris brevis muscle, into its two terminal branches, superficial and deep. 

 Branches. The ulnar nerve gives off no branches till it reaches the forearm. 

 In the forearm it gives off articular, muscular, and cutaneous branches. 



---Radial nerve 



Posterior cu- 

 ""taneous nerve 

 of the arm 



Proximal branch of dorsal 



cutaneous nerve of -- 

 forearm 



Distal branch of dorsal 



cutaneous nerve ... 

 of forearm 



Ulnar nerve 



FIG. 619. THE AXILLARY AND RADIAL NERVES. 



