NEUROLOGY 283 



side of the plexus. It divides into two main branches, one going 

 to the latissimus dorsi and the other to the scapulo-humeralis 

 muscle. From the side are given off branches which supply the 

 patagii muscle and enter into the formation of the dorso-cutaneous 

 plexus. 



The axillaris springs from the second and the third root of the 

 brachial plexus, extends in a lateral direction, passing the ventral 

 and distal rim of the insertional part of the posterior scapulo-hu- 

 meralis or teres et infraspinatus and enters near the capsular liga- 

 ment of the shoulder -joint. It gives off to this joint a small branch, 

 called the recurrent articularis, which passes outward between the 

 triceps brachialis and the humerus. It lies on the inner side of the 

 major deltoid, and patagii muscles, and also the skin of the lateral 

 shoulder and the upper arm region. The recurrent axillaris commu- 

 nicates with the main branch of the radial nerve. 



The cutaneus brachii superior is a small nerve which springs 

 from the last brachial plexus root and passes between the skin and 

 the triceps brachii muscle on the dorsal surface of the upper arm, 

 or brachial, region. It extends down over the elbow region, where 

 it gives off numerous branches to the skin of these regions, to the 

 meta-patagium and to the extensor muscles of the upper arm. 



The brachialis longus superior is a large nerve trunk which springs 

 from most of the other plexus roots. It extends around to the 

 dorsal side of the upper arm and supplies the skin, the feathers, and 

 the muscles of the forearm and the hand. Branches from this nerve 

 trunk supply the triceps brachii and other muscles of the region. 

 The main branch passes between the radius and the ulna, and, pass- 

 ing the elbow-joint, gives off branches to that joint. Passing on, it 

 divides into two branches. One of these extends superficially over 

 the upper part of the condylus ulnaris and supplies the extensor 

 digitorum communis and the extensor metacarpi ulnaris, or flexor 

 metacarpi radialis muscles, and, continuing superficially to the 

 ulnar side, is distributed to the skin of the region. The second, a 

 deep branch, extends on the ulnar side of the radius over the ex- 

 tensor indicis longus, and innervates the latter muscle, the extensor 

 pollicis longus, the extensor pollicis brevis, the adductor pollicis, the 

 interosseous palmaris, and the flexor digitorum. 



The inferior brachial plexus gives off the following branches: 



The supra-coracoideus, a large nerve which springs from the 



