The =tibial nerve= (N. tibialis), also termed the posterior tibial, is
the direct continuation of the great sciatic nerve (Figs. 451, 455, 458,
459, 527). It passes down between the two heads of the gastrocnemius,
and accompanies the recurrent tibial vessels to the distal third of the
leg, where it divides into internal and external plantar nerves. In the
upper third of the leg it lies along the inner side of the superficial
flexor under cover of the internal head of the gastrocnemius; lower down
it is covered by the common deep fascia and is situated in the space
between the deep flexor and the inner border of the tendo Achillis.
At the usual point of election for tibial neurectomy, _i. e._, about a
handbreadth above the level of the tuber calcis, the nerve lies in
areolar tissue and fat in a fascial compartment formed by the special
fascia of the deep flexor in front and by the common fascia and the
accessory or tarsal tendon of the semitendinosus and biceps femoris
behind and internally.
At its origin the tibial nerve gives off a =muscular branch= (Ramus
muscularis distalis), the divisions of which pass between the two heads
of the gastrocnemius and radiate to supply that muscle, the popliteus,
the soleus, and the flexors of the digit. Small cutaneous twigs are also
detached along the course of the nerve.
[Illustration: