TEE BEACHIAL PLEXUS. 



759 



and descending ramuscules, 

 enters the substance of the 

 coraco-radialis. It also fur- 

 nishes filaments to the coraco- 

 huraeralis, before its passage 

 between the two branches of 

 that muscle. Besides this, it 

 concurs, by a small branch, in 

 the formation of one of the 

 anterior thoracic nerves. 



12. Radial Nerve. (Figs. 347, 

 16 ; 348, 3.) 



This is certainly the largest 

 nerve furnished by the brachial 

 plexus. It arises chiefly from 

 the first dorsal pair, and is 

 directed backwards and down- 

 wards, on the inner face of the 

 subscapularis and adductor mus- 

 cle of the arm, whose direction 

 it crosses. In this portion of its 

 course, it proceeds parallel to 

 the humeral artery, from which 

 it is separated by the ulnar 

 nerve. Arriving at the deep 

 humeral artery, which it leaves 

 on the outside, it passes behind 

 the humerus with the divisions 

 of that artery, and enters be- 

 tween the large extensor and 

 short flexor of the fore-arm. 

 After creeping along the pos- 

 terior border of the latter 

 muscle, it gains the anterior 

 face of the ulnar and radial ar- 

 ticulations, where it is covered 

 by the two principal extensors 

 of the metacarpus and the pha- 

 langes, and meeting the radial 

 artery, accompanies it on to the 

 oblique extensor of the meta- 

 carpus. There it terminates by 

 two branches which enter the 

 texture of that muscle. 



1, Subscapular nerve ; 2, Axil- 

 lary nerve ; 3, Radial nerve ; 4, 

 Superficial ramuscule of the 

 musculo-cutaneous nerve ; 5, 

 Ulnar nerve ; 6, Its terminal 

 cutaneous branch. A, Anterior 

 radial artery. 



Fig. 348. 



EXTERNAL NERVES OF THE ANTERIOR LIMB. 



