BY WILLIAM A. IIASWELL, M.A., B.SC. 305 



The sciatic nerves run parallel with the sciatic artery down the 

 thigh. The internal sciatic nerve gives off, while in the thigh, a 

 long cutaneous branch to the outside of the leg ; it then sends 

 off a communicating branch to the external popliteal nerve, and 

 a little lower down gives off a branch which runs down to the ham, 

 where it bifurcates — one division ending in the gastrocnemius 

 externus, the other passing deeper to supply the flexor perf oratus 

 sccundus secundi digiti and flexor perforatus secundus tertii digiti. 

 Soon afterwards the main trunk (internal popliteal nerve J bifurcates; 

 the outer branch breaks up into numerous twigs for the supply 

 of the inner group of superficial flexors of the toes ; the inner 

 sends off (1) a long slender twig which passes down the leg on 

 the surface of the flexor profundus digitorum, and the flexor 

 lomms hallucis, and afterwards in contact with the tibia to the 

 ankle, where it becomes cutaneous; (2) branches of supply for 

 the gastrocnemius interims and tibialis posticus muscles ; (3) 

 branches to the flexor longus hallucis and flexor profundus 

 digitorum. 



The external sciatic nerve ( 'external popliteal) gives off in the thigh 

 a branch of supply for the biceps muscle. It subsequently gives 

 origin to a long branch, which, (after passing with the main 

 trunk of the nerve under the ligament of the biceps), runs down 

 to the foot beneath the superficial flexor muscles. A series of 

 branches then radiate from the main trunk of the nerve as it passes 

 beneath the tendon of the biceps in the back of the leg ; the first 

 of these passes to the front of the leg, the next two or three 

 supply the two outer superficial flexors, the peroneus longus, the 

 extensor communis digitorum and the tibialis anticus. The main 

 trunk finally divides into two branches which turn round the 

 outside of the fibula to the front of the leg. 



Of these, the outer runs superficially over the ankle-joint giving 

 off in its course some small branches to the deeper structures on 

 the front of the tarso-metatarsus, and finally divides at the base 

 of the outer toe, supplying branches to both sides of that digit 



