GREAT SCIATIC NERVE 



ro7 



posterior head of the superficial gluteus. The inferior nerve runs downward and 

 backward on the sacro-sciatic ligament and divides into the posterior cutaneous 

 nerve and muscular branchc^s which supply the semitendinosus. The former (N. 

 cutaneus femoris caudalis) passes through the biceps femoris, emerges between 

 that muscle and the semitendinosus a little below the level of the tuber ischii, and 

 ramifies subcutaneously on the outer and posterior surfaces of the hip and thigh 

 (Fig. 525). 



Great Sciatic Nerve 

 The great sciatic nerve (N. ischiadicus) (Figs. 451, 455, 526), the largest in 

 the body, is derived chiefiy from the last lumbar and the sacral roots of the lumbo- 

 sacral plexus, but may receive a fasciculus from the third sacral nerve also. It 



Sncral spines 



Aponeurosis 

 of lomjissi- 

 mus dor si 



lumbar 

 vertebrce 



Sacro-sciatic 

 ligament 



Coccygeal 

 vertebrce 



Lateral sacro- / ■^'/^ "V' 



iliac ligament \ , 



MaynmiUnry 

 process 



Branches of anterior gluteal artery 

 and nerve 



Tube 

 ischii 



Lesser Gemel- Anastomosis 

 sciatic lus between ob- 



foramen lurator and 



internal pvdic 

 veins 



Fig. 526. 

 Nervus i.schiadicus = great sciatic 



A cetab ular fossa 



" Acetabular notch 



Pubic eminence 



^Obturator artery 

 ^Obturator internus 

 ''Obturator vein 



— Vessels and Nerves on Pelvic W.\ll of Horse. 



nerve; n. glut. inf.=anterior ghifeal nerve; n. pudendus = internal pudic nerve. 

 (.\fter Schmaltz, Atlas d. .\nat. d. Pferdes.) 



emerges through the great sacro-sciatic foramen as a l)road fiat band — blended at 

 first with the posterior gluteal nerve — which passes downward and backward on 

 the lower part of the sacro-sciatic ligament and on the origin of the deep gluteus 

 muscle. It turns downward in the hollow between the trochanter major and the 

 tuber ischii over the gemellus, the tendon of the obturator internus, and the quad- 

 ratus femoris. In its descent in the thigh it lies between the biceps femoris ex- 

 ternally and the adductor, semimem}:)ranosus, and semitendinosus internally, and 

 it is continued between the two heads of the gastrocnemius as the tibial nerve. Its 

 chief branches are as follows : 



