II 



the N. ulnahs to this branch of the N. radiahs suppKed to the tensor fasciae 

 antebrachii. (b) A large fasciculus composed of several branches, some 

 of which recurve slightly around the tendon of the teres major and latis- 

 simus; all the branches of this fasciculus are distributed to the caput 

 longum tricipitis (PI. I, 41). (c) Branches to the caput laterale tricipitis, 

 caput mediale tricipitis, and anconeus. Of these branches the small one 

 to the caput mediale is readily found and traced to its muscle; the branches 

 to the caput laterale and anconeus, however, are more or less completely 

 hidden by the caput longum and caput laterale and often can be satis- 

 factorily demonstrated only after the caput laterale has been dissected 

 as follows: Turn aside the skin and the panniculus from the outer surface 

 of the triceps. The posterior surface of the caput laterale- may now be 

 freely separated from the caput longum, but in dissecting up the anterior 

 border of the muscle care should be taken not to cut the cutaneous nerve 

 (a branch of the N. radialis) which emerges from beneath the muscle at, 

 or close to, its anterior border (6 to 8 cm. distal to the cutaneous branch 

 of the N. axillaris, or 8 to 10 cm. from the posterior edge of the M. deltoideus, 

 PI. II, c). Transect the caput laterale a little distal to its middle and 

 freely reflect the distal portion of the muscle; the proximal portion of the 

 muscle can be turned aside only a little distance as the nerve and blood- 

 vessels to the muscle enter its deep or anterior face. Trace this nerve and 

 also the cutaneous branch to their origin from the N. radialis. Now trace 

 the main trunk of the N. radialis in its course along the musculo-spiral groove 

 to the point where it passes beneath the M. extensor carpi radialis at its 

 origin, near the proximal end of the external epicondyle of the humerus 

 (PL II, 1 1 , 25) . Remove the skin of the antebrachium as far as to the carpus. 

 Trace the cutaneous branches of the N. axillaris and the N. radalis, the 

 former to the antero-internal side of the antebrachium and the latter to 

 the antero-extemal side of the antebrachium. Both of these cutaneous 

 branches may readily be traced to near the carpus. The M. extensor carpi 

 radialis should now be dissected as follows: Transect it near the middle 

 and freely turn aside the distal portion, but in turning aside the proximal 

 part of the muscle care must be exercised to avoid cutting or breaking 

 the nerves and blood-vessels that enter the deep face of the muscle (near 

 the posterior border of the distal end of the M. brachialis). Now trace the 

 N. radialis beneath the proximal portion of the extensor carpi radiahs 

 taking care not to cut the branches of this nerve, usually three in number, 

 that enter the deep face of the muscle (PL II, d). The main nerve now 

 passes beneath the extensor digitalis commtinis, near the origin of the 

 muscle. Transect the extensor digitahs communis near the middle of the 

 antebrachium and as the proximal portion is reflected avoid breaking the 



