640 



SPINAL NERYES. 



Fig. 350. Cutaneous Nerves of 

 Riuht Upper Extremity. Anterior 

 View. 



The Subscaplular Nerves, three in number, supply the Subscapularis, Teres 

 Major, and Latissimus Dorsi muscles. 



The upper subscapular nerve, the smallest, enters the upper part of the Sub- 

 scapularis muscle. 



The lower subscapular nerve enters the axillary border of the Subscapularis, 

 and terminates in the Teres Major. The latter muscle is sometimes supplied 

 by a separate branch. 



The long subscapular, the largest of the three, descends along the lower border 



of the Subscapularis to the Latissimus Dorsi, 

 through which it may be traced as far as its 

 lower border. 



The Circumflex Nerve (Fig. 353) supplies some 

 of the muscles, and the integument of the shoul- 

 der, and the shoulder-joint. It arises from the 

 posterior cord of the brachial plexus, in common 

 with the musculo-spiral nerve. It passes down 

 behind the axillary artery, and in front of the 

 Subscapularis; and, at the lower border of that 

 muscle, passes backwards, and divides into two 

 branches. 



The upper branch winds round the neck of the 

 humerus, beneath the Deltoid, with the posterior 

 circumflex vessels, as far as the anterior border 

 of the muscle, supplying it, and giving off cuta- 

 neous branches, which pierce it to ramify in the 

 integument covering its lower part. 



The lower branch, at its origin, distributes fila- 

 ments to the Teres Minor and back part of the 

 Deltoid muscles. Upon the filament to the for- 

 mer muscle a gangliform enlargement usually 

 exists. The nerve then pierces the deep fascia, 

 and supplies the integument over the lower two- 

 thirds of the posterior surface of the Deltoid, as 

 well as that covering the long head of the 

 Triceps. 



The circumflex nerve, before its division, gives 

 off an articular filament, which enters the shoul- 

 der-joint below the Subscapularis. 



The Musculo-cutaneous Nerve (Fig. 352) (exter- 

 nal cutaneous, perforans Casserii), supplies some 

 of the muscles of the arm, and the integument of 

 the forearm. It arises from the outer cord of the 

 brachial plexus, opposite the lower border of the 

 Pectoralis Minor. It then perforates the Coraco- 

 brachialis muscle, and passes obliquely between 

 the Biceps and Brachialis Anticus, to the outer 

 side of the arm, a little above the elbow, where it 

 perforates the deep fascia and becomes cutaneous. 

 This nerve, in its course through the arm, sup- 

 plies the Coraco-brachialis, Biceps, and Brachialis 

 Anticus muscles, besides sending some filaments 

 to the elbow-joint and humerus. 



The cutaneous portion of the nerve passes be- 

 hind the median cephalic vein, and divides, opposite the elbow-joint, into an 

 anterior and a posterior branch. 



The anterior branch descends along the radial bonier of the forearm to the 

 wrist. It is here placed in front of the radial artery, and, piercing the deep 



