THE NERVOUS SYSTEM. 323 



the elbow, where it passes between the heads of the flexor carpi 

 ulnaris. Its branches are. in the forearm: 



,4-t^r 



Articular (elbow), supplies the elbow-joint; 



Muscular, to inner half of the deep flexors and flexor carpi ulnaris ; 

 Cutaneous, supplies the skin of the palm; 



Dorsal cutaneous, supplies both sides of the little finger and the 

 ulnar side of the ring finger; 



Articular (wrist), supply the wrist-joint. 



In the hand : 



Superficial palmar, supplies the skin of both sides of the little and 

 the ulnar side of the ring finger and palmaris brevis muscle ; 



Deep palmar, supplies the interossei, lumbricales, adductor pollicis, 

 and inner head of flexor brevis pollicis. 



The musculo-spiral nerve, derived from the posterior cord 

 of the brachial plexus, descends the arm in front of the teres 

 major and latissimus dorsi muscle, accompanies the superior 

 profunda artery through the musculo-spiral groove to the outer 

 side of the elbow, between the supinator longus and the brachialis 

 anticus, where it divides into the radial and posterior interosseous 

 nerves. Its branches are : 



Muscular, supply the supinator longus, external carpi radialis- 

 longior, triceps, anconcus, and brachialis anticus; 



Radial, descends in the course of the radial artery to three inches 

 above the wrist, where it becomes superficial, and supplies the adjoining 

 sides of the thumb and index, index and middle, middle and ring fingers. 



Cutaneous, supply the outer side of the arm, elbow, and radial side 

 of forearm and wrist; 



Posterior interosseous, passes through the supinator brevis muscle, 

 and supplies, as it descends, all the posterior brachial and radial muscles, 

 except those supplied by the muscular branches of the ulnar. It has a 

 ganglion upon it. 



DORSAL NERVES. The posterior divisions of the dorsal 

 nerves subdivide into the external and internal branches to supply 

 the muscles of the skin of the back. The anterior divisions of 

 the dorsal nerves (intercostal nerves), twelve in number., supply 

 the walls of the abdomen and thorax. They are divided into two 

 sets the six upper, distributed for the most part to the walls 

 of the chest, and the six lower, to the walls of the chest and 

 abdomen. The upper six dorsal nerves run between the two sets 

 of the intercostal muscles, accompanied by the intercostal vessels, 

 to supply the skin over the front of the chest and the mammae. 

 Their branches are: 



Lateral cutaneous, divide into two branches, anterior and posterior; 

 Anterior brandies, to the skin of the chest and mammae principally; 

 /'o.v/rn'or brunches, to the skin over the scapular and lower dorsal 

 regions. 



