THIGH AND BUTTOCK. 



through the sacro-sciatic ligament to the skin near the coc- 

 cyx. [655-658] 



Small Sciatic. Springing from the backs of the first three 

 sacral nerves at the junction of the sacral and pudendal plex- 

 uses, this runs through the great sciatic notch below the Pyri- 

 formis, descends behind the great sciatic, and then continues 

 over the hamstrings to end as the sural branches. It is purely 

 cutaneous, and has the following branches : Perineal (inferior 

 pudendal) ; arising at the lower border of the Gluteus maxi- 

 mus and running inward over the hamstrings below the isphial 

 tuberosity, this becomes subcutaneous over the pubic arch 

 and supplies the scrotum and root of the penis (labium majus 

 and clitoris) communicating with the pudic and ilio-inguinal ; 

 collateral branches supply the upper and inner part of the 

 thigh. Gluteal; many large branches arising under the Gluteus 

 maximus and piercing the fascia lata along its lower border to 

 supply the lower half of the buttock, from the great trochanter 

 almost to the coccyx. Femoral; two sets, internal and exter- 

 nal, pierce the fascia lata at intervals and supply the back of the 

 thigh on its inner and outer sides respectively. Sural; two or 

 more branches which pierce the popliteal fascia and supply 

 the calf. [655] 



Pudic. Arising usually from the second, third, and fourth 

 sacral this runs through the great sacro-sciatic foramen below 

 the great sciatic nerve, and across the ischial spine (or lesser 

 sacro-sciatic ligament) ; then running through the small sacro- 

 sciatic foramen with the pudic artery, and along the outer wall 

 of the ischio-rectal fossa in a special sheath of parietal pelvic 

 fascia, it divides at the base of the triangular ligament into the 

 perineal nerve and the dorsal nerve of the penis. The inferior 

 hemorrhoidal, its other branch, arises in the back of the ischio- 

 rectal fossa usually, but may arise separately from the plexus 

 (third and fourth sacral) and accompany the pudic. All these 

 branches of the pudic go to the perineum and adjacent genitals 

 (see page 203). [658] 



[287] 



