Spinal Nerves. 



151 



3. External or m u s c u 1 o- 

 cutaneous, N. cutaneus braclui 

 externus s. musculo-cutaneus arises 

 from the outer cord of the bra- 

 chial plexus. It perforates the 

 M. coraco-bracliialis, passes ob- 

 liquely between M. biceps and 

 M. bracliialis anticus to the elbow, 

 where it pierces the fascia of 

 the upper arm, accompanies the 

 cephalic vein to the back of the 

 hand and communicates with the 

 dorsal branch of the radial nerve. 

 It supplies the MM. coraco-bra- 

 chialis, biceps and brachialis anticus, 

 and the integument on the radial 

 side of the forearm. 



4. Circumflex, N. circum- 

 flexus s. axillaris, arises from the 

 posterior cord of the plexus, and 

 winds around the neck of the 

 humerus in company with the 

 posterior circumflex artery; it 

 supplies the capsule of the shoul- 

 der-joint; with a cutaneous branch 

 the posterior region of the shoul- 

 der and upper arm ; with muscu- 

 lar branches the M. teres minor 

 and M. ddtoides (see Fig. 499). 



5. Median nerve, N. me- 

 dianus, arises by two ropts, one 

 from the outer and one from the 

 inner cord of the brachial ple- 

 xus; these embrace the lower 

 part of the axillary artery (see 

 Fig. 493). It descends in the 

 Sulcus bicipitalis interims, lying 

 at first to the outer side of the 

 brachial artery, then crosses the 

 vessel above the elbow and lies 

 to its inner side, and beneath 

 the M. pronator radii teres and 

 M. flexor carpi radialis, to within 

 two inches above the annular liga- 

 ment, where it becomes more super- 



H. MUSCULO-CUTAN. 

 N. RADIAL. 

 R. PROFUND. 



r-N. MEDIAN. 



N. MUSCULO- 

 CUTAN 



R. CUTAN. 

 N. AXILLAR. 



A. Irachial 



R. SUPERF. 



INTEROSS. INT. 



'.4.. ulnar. 



N. ULNAR. 

 A- radial. 



. PROFUND. 

 N. ULNAR. 



495, The Nerves at the 



Flexor Surface of the 



Upper Extremity. 



