408 SPECIAL ANATOMY. 



skin of the arm, on the posterior surface, downwards as far as the 

 olecranon, on the inside ; as well as the anterior surface ; uniting 

 above the olecranon with the principal trunk of the middle cutane- 

 ous nerve. 



2. N. cutaneus medius s. internus major, arises from the in- 

 ferior portion of the plexus or from n. ulnaris and medianus (at 

 first on the ven. axillar., then on the ven. basilica), afterwards 

 between them, downwards along the boundary of the anterior and 

 internal surface of the upper arm, beneath the fascia, giving above 

 branches to the axilla and to the skin along the m. biceps, and 

 divides into an external branch for the anterior surface and an in- 

 ternal for the ulnar border of the fore-arm, the branches of which 

 extend as far as the carpal articulation. 



In the bend of the arm it is situated over ven. mediana, rather 

 internally, towards the condylus internus. (The outer side of the 

 vein is therefore selected in venesection.) 



3. JV. cutaneus externus s. musculo-cutaneus s. perforans Cas~ 

 serii, arises close to the n. medianus or with it, from the fifth to 

 the seventh cervical nerves, perforates the m. coracoideus and 

 passes obliquely between biceps and brachial. intern, outwards, 

 passes downwards to the v. cephalica, and close to this on the 

 fore-arm, in the inferior half of which it divides into a volar and 

 a branch for the radial border, which terminates in the skin over 

 the carpal articulation. Branches to : m. coraco-brachialis, 

 biceps, brachialis internus, and to the skin of the anterior sur- 

 face of the lower arm. 



660. Muscular nerves. 



4. N. axillaris s. circumflexus humeri, arises from the inferior, 

 middle part of the plexus, curves inwards and backwards, behind 

 anconceus long, [triceps] around the highest part of the humerus 

 with art. circumfl. humeri post., and terminates in the skin be- 

 tween the axilla and upper arm on the posterior surface. Branches 

 to : m. subscapul., [?] teres major [?] and minor, deltoid, to art. 

 axillaris, the shoulder joint, and into the bones ; lastly : 



N. cutaneus humeri posterior superior [there are generally 

 two, even three branches], perforates the m. deltoideus, 

 and ramifies in the posterior, superior, and outer region of 

 the upper arm. 



5. Nerv. ulnaris s. cubitalis, arises from the inner part of the 

 plexus, from the sixth to the eighth cervical, and first dorsal nerve, 

 passes downwards on the inner side of art. axillar. and brachi- 

 alis behind ven. axillaris, perforates the fascia, and goes between 



