POSTERIOR TIBIAL NERVE. 677 



b. The small nerve of the idantaris muscle is derived from the outer of the branches 

 just described, or directly from the main trunk (internal popliteal). 



c. The soleus receives a branch of considerable size, which enters the muscle on the 

 posterior aspect after descending to it in front of the gastrocnemius. 



d. The nerve of the popliteus muscle lies deeper than the preceding branches, and 

 arises somewhat below the joint ; it descends along the outer side of the popliteal 

 vessels, and, after turning beneath the lower border of the muscle, enters the deep or 

 anterior surface. 



EXTERNAL OE SHORT SAPHENOUS NERVE. 



The cutaneous branch of the internal popliteal nerve (ramus communicans 

 tibialia) descends along the leg beneath the fascia, resting on the gastro- 

 cnemius, in the furrow between the heads of the muscle, to about midway 

 between the knee and the foot. Here it perforates the fascia, and a little 

 lower down is usually joined by a branch from the external popliteal nerve 

 (communicans peronei). After receiving this communicating branch, the 

 external saphenous nerve descends beneath the integument near the outer 

 side of the tendo Achillis in company with the short saphenous vein, and 

 turns forwards beneath the outer malleolus to end in the skin at the side of 

 the foot and on the little toe. On the dorsum of the. foot this nerve com- 

 municates with the musculo- cutaneous nerve. 



In many cases, the external saphenous nerve supplies the outer side of the fourth 

 toe, as well as the little toe. The union between the saphenous nerve and the branch 

 cf the external popliteal nerve occurs in some cases higher than usual, occasionally even 

 at or close to the popliteal space. It sometimes happens that the communication 

 between the nerves is altogether wanting ; in which case the cutaneous nerve to the 

 foot is generally continued from the branch of the internal popliteal nerve. 



POSTERIOR TIBIAL NERVE. 



The internal popliteal nerve receives the name of posterior tibial at the 

 lower margin of the popliteus muscle. It passes down the leg with the pos- 

 terior tibial artery, lying for a short distance at the inner side of the vessel, 

 and afterwards at the outer side ; the artery inclining inwards from its origin 

 while the nerve continues its straight course. In the interval between the 

 inner malleolus and the heel, it divides into the two plantar nerves (internal 

 and external). The posterior tibial nerve, like the accompanying vessels, is 

 covered at first by the muscles of the calf of the leg, afterwards only by 

 the integument and fascia, and it rests upon the deep-seated muscles. 



Lateral branches. The deep muscles on the back of the leg and the 

 integument of the sole of the foot receive branches from the posterior tibial 

 nerve in its course along the leg. 



a. The muscular branches emanate from the upper part of the nerve, either sepa- 

 rately or by a common trunk ; and one is distributed to each of the deep muscles, 

 viz., the tibialis posticus, the long flexor of the toes, and the long flexor of the great 

 toe. The branch which supplies the last-named muscle runs along the peroneal 

 artery before penetrating the muscle. 



b. A calcaneo-plantar cutaneous branch is furnished from the posterior tibial nerve ; 

 the plantar part perforates the internal annular ligament, and ramifies in the integu- 

 ment at the inner side of the sole of the foot, and beneath the heel. 



INTERNAL PLANTAR NERVE. 



The internal plantar, the larger of the two nerves to the sole of the foot, 

 into which the posterior tibial divides, accompanies the internal or smaller 

 plantar artery, and supplies nerves to both sides of the three inner toes, and 

 to one side of the fourth. From the point at which it separates from the 



