302 JOUKNAL OF CoM PA K A 11 VK NkUKOI.OGV. 



cephalic braiicJi is distributed to the M. gluteus medius (M. 

 gl. med.), which lies ectad of the nerve and whose ental 

 surface it penetrates; tlie caudal branch is distributed to the 

 M; gluteus minimus (M. gl. min.), which lies entad and 

 caudad — these two rami are the homologue of the superior 

 branch of anthropotomy; the middle branch — inferior of 

 anthropotomy — the largest branch, perforates the M. gluteus 

 minimus and innerves the M. tensor vaginae femoris (T.V.F.), 

 in which it can be traced to the distal fourth. A few fila- 

 ments are given to the M. gluteus minimis. 



N. ISCHIADICUS. 



The great sciatic nerve (Fig. Ischiad.) is the largest of 

 the spinal nerves; its ectal origin is the sacral plexus, or the 

 union of the first and second sacral nerves. Within the 

 pelvis, its course is caudad to the sciatic foramen; peripherad 

 of the pelvis it lies upon the ectal border of the M. obturator 

 internus and the MM. gemelli, mesad of the great trochanter, 

 laterad of the ischiac tuberosity, and entad of the MM. pyri- 

 formis, biceps and glutei. Its exposure is effected in the 

 meros by the removal of the M. gluteus maximus and the M. 

 biceps. The great sciatic nerve is cutaneous and muscular in 

 its distribution; it supplies the integument of nearly all the 

 caudal limb, and the muscles of the meros, the crus, and the 

 pes as given below. 



Principal Rami. — The Jirst branch is given off at the 

 union of the second sacral nerve, and innerves the M. quad- 

 ratus femoris (Fig. Qiiad.). The second branch is the sciatic 

 root of the pudic nerve (q. v.), in common with the root of a 

 gluteal nerve (b. v.). The third branch is a considerable 

 nerve entad of the M. pyriformis, and which is divided into 

 three smaller rami: (a) the first of which enters the ental 

 surface of the M. biceps, 5-8 mm. peripherad of its origin 

 (Fig. M. bi.); [b) the second is covered by the M. biceps, 

 to which it gives it ramulus at its mesal (lower) border, and 

 continues entad of the M. semi-tendinosus and a plexus ot 



