extremities. 65 



5, Great sciatic, or great femoro-popliteal. — 

 Passes tlirouo^h tlie 2:reat sciatic notch outside the isclii- 

 atic ligament, over the small glutens, behind the 

 gemelli of the pelvis and the square crural, bends 

 downwards behind the femur in front of the ischio- 

 tibial muscles, passes between the bellies of the 

 bifemoro-calcaneus, behind the perforatus, reaches the 

 hock, and at the os calcis divides into the external and 

 internal plantar nerves. Collateral branches : 1 — The 

 external sciatic-popliteal, or small femoro-popliteal, 

 runs forwards and downwards between the long vastus 

 and the gastrocnemius externus, and on the outside 

 of the superior extremity of the leg terminates in the 

 musculo-cutaneous and anterior tibial branches. The 

 musculo-cutaneous passes under the tibial aponeurosis 

 between the anterior and lateral extensors of the pha- 

 langes, becoming subcutaneous to terminate. The 

 anterior tibial runs under the anterior extensor pedis 

 to the front of the hock, with the pedal artery down 

 to the fetlock, where it ends by cutaneous filaments. 

 2 — Branches to the deep muscles of the internal crural 

 region. Leaving the sciatic at the middle of the supra- 

 cutyloid crest, these branches pass behind the coxo- 

 femoral joint and branch off to the muscles. 3 — 

 Branches to the posterior crural muscles, rising from 

 the sciatic at the gemelli muscles, and then te.'minating 



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