SACRAL NERVES. 



167 



the pelvis at the upper portion of the thyroid foramen, 

 buted upon the obturator and adductor muscles. 



It is distri- 



SACRAL NERVES. 



Fig. 145. 



These are five and sometimes six in number ; the anterior trunks, 

 with a portion of the last dorsal, constitute the sacral plexus. From 

 it are given off a few small branches and to the viscera and muscles 

 within the pelvis. There also arise from it the gluteal,^ which 

 emerging from the sacro-sciatic notch, divides into two large 

 branches to supply the glutei muscles. The i7?ter97al pudic^ or supe- 

 rior long pudendal^ which accompanies the internal pudic artery, 

 and supplies the perineum, and organs of 

 generation ; it divides into two branches, 

 the superior continuing to the extremity of 

 the penis with the dorsal artery. The 

 lesser ischiatic* divides into the inferior 

 long pudefidal, which winds around the 

 tuberosity of the ischium, and is distributed 

 to the integuments of the perineum ; and the 

 posterior cutaneous^ a long filament passing 

 down the back of the thigh and leg, to be 

 spent upon the integuments. The great 

 sciatic^ is the largest nerve in the body ; it 

 escapes from the pelvis beneath the pyrifor- 

 mis muscle, and descends the back of the 

 thigh between the flexor muscles ; about one- 

 third above the knee it divides into two large 

 branches, called peroneal and popliteal. 

 The popliteal descends through the popli- 

 teal space, giving off numerous muscular 

 branches, one of which is the external saphe- 

 nous nerve, which becomes superficial near 

 the ankle, and is joined by the external 

 peroneo-cutaneous nerve ; it then passes 

 behind the external malleolus, and supplies 

 the external malleolus and the foot. The posterior tibial is a con- 

 tinuation of the popliteal, descending the back of the leg in company 

 with the posterior tibial artery ; it is finally distributed upon the sole 

 of the foot by two branches called the external ^wdi internal plantar 

 nerves. 



The peroneal nerve extends towards the head of the fibula, where 

 it gives off two small cutaneous branches^ distributed about the joint, 

 called internal and external perojieo-cutaneous ; the internal joins 

 with the external saphenous, and thus forms the communicans tibicB, 

 The peroneal now divides into the external peroneal and anterior 

 tibial ; the external peroneal passes down upon the fibular side of the 



