288 ANATOMY OF THE RABBIT 



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 mal- 

 leolus 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 or sural nerve separates from the tibial 

 before it reaches the gastrocnemius muscle and accompanies the 

 small saphenous artery and vein on the posterior margin of the 

 lateral head of the gastrocnemius. It is distributed in the skin and 

 fascia of the ankle and heel, one terminal branch passing under the 

 external malleolus to the lateral and ventral surfaces of the calcaneus. 



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 

 exposed by 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, where it 

 becomes associated with the peroneal artery. It passes with the 

 latter over the fibular side of the crural ligament and branches over 

 the whole dorsal surface of the foot (a distribution somewhat more 

 extensive than in most animals). The nerve distributes branches 

 to the tibialis anterior, to the extensor digitorum longus, and to 

 the peronaeus muscles. 



In man and most mammals, a common peroneal nerve divides into a super- 

 ficial and a deep branch, but the latter appears to be absent in the rabbit. 



The Lumbosacral Plexus 

 The structure of the lumbosacral plexus may be examined by 

 breaking 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 portion of the psoas and 

 iliacus muscles may be picked away with the forceps, and the 



