508 NERVOUS SYSTEM. 



ham, and there divides into several filaments, which are distri- 

 buted to the integuments on the back of the leg. 



The Nervus Pudendalis Longus Superior comes from the 

 third and fourth sacral. It goes in company with the internal 

 pudic artery between the sacro-sciatic ligaments, and then di- 

 vides into two branches; the inferior is distributed to the inte- 

 guments and muscles of the perineum, to the urethra and scro- 

 tum; the superior passing alog the ramus of the ischium and 

 pubes with the trunk of the internal pudic artery, is distributed 

 to the obturator internus, accelerator urinae, urethra, and after- 

 wards, getting between the symphysjs of the pubes and the 

 penis, terminates on its integuments and the glans penis. 



The Nervus Ischiadicus, or the Great Sciatic, is the com- 

 mon trunk, formed from the sciatic plexus; it is much the 

 largest nerve in the body, and passes from the pelvis between 

 the pyriformis and the geminus superior. It crosses, vertical- 

 ly, the small rotator muscles of the thigh, being concealed by 

 the inferior edge of the glutseus magnus; it is there about half- 

 way between the tuberosity of the ischium and the trochanter 

 major. Thence it descends on the back of the adductor mag- 

 nus, at the outer edge of the long head of the biceps flexor cru- 

 ris. About half way down the thigh, sometimes a little lower, 

 the Sciatic Nerve divides into the Popliteal, or Posterior Tibi- 

 al, and Peroneal. Occasionally this division takes place as high 

 as the exit of the nerve from the pelvis; but in this case the 

 fasciculi are parallel with each other as far as the middle of the 

 thigh. From the trochanter minor to its usual place of division, 

 this nerve is parallel with, and on the back of the thigh bone; 

 afterwards the two branches begin to diverge. The popliteal 

 nerve continues straight downwards to the back and middle 

 of the knee-joint, and to the interstice between the heads of the 

 gastrocnemius muscle; whereas the peroneal nerve goes along 

 the inner posterior edge of the biceps flexor cruris, and passes 

 between its tendinous insertion and the external head of the 

 gastrocnemius muscle. 



In this course, the following branches are sent from the sci- 

 atic. -Twigs to the little rotator muscles of the thigh. The 

 Cutaneus Internus Superior, which arises near the upper part 

 of the thigh, and is distributed to the skin of the corresponding 



