154 Anatomy of the Rabbit. 



saphenous nerve, and is continued as the posterior tibial vein (v. tibialis 

 posterior), to the plantar surface of the foot. 



The popliteal vein, the root of the femoral, accompanies the corre- 

 sponding artery in the popliteal fossa. It receives the small saphenous 

 vein (v. saphena parva) from the posterior margin of the lateral head of 

 the gastrocnemius. 



The sciatic vein is continued on the lateral surface of the leg as the 

 anterior tibial vein (v. tibialis anterior) . It receives the accessory small 

 saphenous vein (v. saphena parva accessoria) from the posterior surface, 

 and is continued to the dorsum of the foot passing to the fibular side of 

 the crural ligament. 



***The greater saphenous nerve, the posterior branch of the femoral 

 nerve, accompanies first the femoral artery and afterwards the great 

 saphenous artery, passing distad to the medial surface of the leg. 



The tibial nerve, the posterior division of the sciatic, passes between 

 the medial and lateral heads of the gastrocnemius to the medial surface 

 of the head of the plantaris. It traverses the leg, lying on the medial 

 surface first of the popliteus and afterwards of the flexor digitorum 

 longus, and passing beneath the medial malleolus reaches the plantar 

 -surface of the foot. In the proximal portion of the leg it distributes 

 muscular branches to the flexor group. 



The lesser saphenous nerve (n. saphenus minor) accompanies the 

 small saphenous artery and vein on the posterior margin of the lateral 

 head of the gastrocnemius. 



The peroneal nerve, the anterior division of the sciatic, passes distad, 

 lying at first between the insertion of the biceps and the lateral head of 

 the gastrocnemius, and thus appearing on the surface after the removal 

 of the former. It perforates the anterior portion of the lateral head of 

 the gastrocnemius and afterwards the fused heads of the peronaeus 

 tertius and flexor digitorum longus, traversing the leg at first behind 

 the peronaeus longus and then around its medial margin to the front of 

 its tendon. It passes to the fibular side of the crural ligament and thence 

 to the dorsum of the foot. The nerve distributes branches to the 

 tibialis anterior and extensor digitorum longus. 



The structure of the lumbosacral plexus may be examined by break- 

 ing away the ventral portion of the pelvis, or by dividing the sacroiliac 

 articulation in such a way that the two sides of the pelvis may be pressed 

 apart, the ventral or pelvic face of the sacrum being thus exposed. 

 The posterior portions of the psoas and iliacus muscles may be picked 

 away with the forceps, and the abductor caudae anterior muscle (p. 183) 

 may be detached from its origin on the ischial spine. 



The lumbosacral plexus (plexus lumbosacralis) is formed by the 

 ventral roots of the four posterior lumbar and four sacral spinal nerves. 

 It is divisible into a lumbar plexus (plexus lumbalis), from which arises 

 the femoral nerve, and a sacral plexus (plexus sacralis), from which 

 arises the sciatic nerve. 



The femoral nerve is formed from the fifth, sixth, and seventh lumbar, 

 especially from the loop connecting the fifth and sixth (ansa lumbalis n). 

 From the same loop arises a smaller, obturator nerve (n. obturatorius), 



