THIGH AND BUTTOCK. 



nerve to the Quadratus femoris, and often from the front of 

 the great sciatic (tibial) near its origin ; they enter the back of 

 the capsule. [649] 



Posterior Series. 



The nerve to the Pyriformis arises from the back of the sec- 

 ond, or first and second sacral nerves and enters the front of 

 the muscle. The superior gluteal arises from the back of the 

 fourth and fifth lumbar and first sacral nerves, and runs out- 

 ward above the Pyriformis and then across the Gluteus mini- 

 mus, under the Gluteus maximus and medius, to end in the 

 under surface of the Tensor vaginae femoris; it supplies the 

 Gluteus medius and minimus. The inferior gluteal arises from 

 the back of the fifth lumbar and first two sacral nerves, runs 

 under the Pyriformis, and at once divides into branches to the 

 Gluteus maximus. [649] 



The nerve to the short head of the Biceps arises from the fifth 

 lumbar and first two sacral nerves, and it usually descends in 

 the sheath of the great sciatic nerve to the mid-thigh. An ar- 

 ticular branch, to the outer side of the knee-joint, generally 

 arises from the great sciatic (peroneal) with the preceding, 

 descends under the Biceps, and divides into upper and lower 

 branches. [649] 



Peroneal or External Popliteal. After leaving the great 

 sciatic this descends through the upper and outer part of the 

 popliteal space, under the Biceps, and then over the outer head 

 of the Gastrocnemius, ending about an inch below the head of 

 the fibula. Collateral branches; to the knee-joint and short 

 head of the Biceps as described just above; sural and peroneal 

 communicating (cutaneous), arising in the popliteal space and 

 descending to the leg. Terminal branches; anterior tibial, re- 

 current tibial, and musculo-cutaneous. [650] 



Tibial or Internal Popliteal. After leaving the great sci- 

 atic, this descends through the popliteal space under the ham- 

 strings, Gastrocnemius, and Plantaris, crossing over the pop- 

 liteal vessels from without inward and then over the Popliteus ; 



[285] 



