774 



THE NERVOUS SYSTEM. 



tfuprascapular. 







Circumflex. 



finger, it supplies the Adductores transversus et obliquus pollicis and the inner head 

 of the Flexor brevis pollicis. It also sends articular filaments to the wrist-joint. 



It will be remembered that the inner part of the Flexor profundus digitorum 

 is supplied by the ulnar nerve ; the two inner Lumbricales, which are connected 

 with the tendons of this part of the muscle, are therefore supplied by the same 

 nerve. The outer part of the Flexor profundus is supplied by the median nerve ; 

 the two outer Lumbricales, which are connected with the tendons of this part of 



the muscle, are therefore sup- 

 plied by the same nerve. 

 Brooks states that in twelve 

 instances out of twenty-one he 

 found that the third lumbrical 

 received a twig from the median 

 nerve, in addition to its branch 

 from the ulnar. 



The Musculo-spiral Nerve 

 (Fig. 414), the largest branch 

 of the brachial plexus, supplies 

 the muscles of the back part 

 of the arm and forearm, and 

 the integument of the same 

 parts, as well as that of the 

 back of the hand. It arises 

 from the posterior cord of the 

 brachial plexus, of which it 

 may be regarded as the con- 

 tinuation. It receives filaments 

 from the sixth, seventh, and 

 eighth, and sometimes also from 

 the fifth cervical nerves. At 

 its commencement it is placed 

 behind the axillary and upper 

 part of the brachial arteries, 

 passing down in front of the 

 tendons of the Latissimus dorsi 

 and Teres major. It winds 

 round the hurnerus in the mus- 

 culo-spii'al groove with the su- 

 perior profunda artery, passing 

 from the inner to the outer side 

 of the bone, between the inter- 

 nal and external heads of the 

 Triceps muscle. It pierces the 

 external intermuscular septum, 

 and descends between the 

 Brachialis anticus and Supi- 

 nator longus to the front of 

 the external condyle, where it 

 divides into the radial and 

 posterior interosseous nerves. 



The branches of the mus- 

 culo-spiral nerve are 

 Muscular. 

 Cutaneous. 



FIG. 414. The suprascapular, circumflex, and musculo-spiral "Rorliril 



nerves. 



Posterior interosseous. 

 The muscular branches are divided into internal, posterior, and external ; 



