210 ELEMENTS OF MAMMALIAN ANATOMY. 



aspect of the biceps to the cranial aspect of the forearm, 

 where it becomes subcutaneous. It supplies the biceps and 

 coracoid muscles and the skin of the forearm. The internal 

 cutaneous arises from the first thoracic and passes along the 

 ventral side of the arm, becoming subcutaneous just proxi- 

 mad of the elbow, where it is distributed to the skin of the 

 'arm and forearm on the caudal and ventral aspects. 



The musculo spiral arises from the seventh and eighth 

 cervical and first thoracic nerves. It is the largest com- 

 ponent of the brachial plexus. It winds obliquely around 

 the humerus to the cranial aspect, where it divides into two 

 branches, the radial and the posterior interosseous. The 

 radial nerve is the smaller and becomes subcutaneous near 

 the elbow, and passes along the radial region. The pos- 

 terior interosseous proceeds along the dorsal aspect of the 

 forearm to the wrist, where it divides into branches supply- 

 ing the digits. 



The median nerve arises from the seventh and eighth 

 cervical and first thoracic. It follows the course of the 

 brachial artery, passing through the supracondylar foramen 

 to the elbow, where it passes beneath the pronator teres to 

 the carpal region, and supplies the first, second, and third 

 digits. It also supplies the pronator teres and flexor 

 muscles of the forearm. 



The ulnar nerve (Fig. 105) is derived from the eighth 

 cervical and first thoracic. It courses with the brachial 

 artery to the middle of the humerus, where it turns caudad 

 to pass between the olecranon process and internal condyle 

 of the humerus. It is here subcutaneous and furnishes the 

 sensation experienced when one strikes what is popularly 

 called his " funny bone," but what is really the ulnar nerve. 

 It then passes down the ulnar side of the forearm, supply- 

 ing some of the flexor muscles, and finally divides to supply 

 the fourth and fifth digits. The ventral branches of the 



