Individual Variation.—In T.p. 3L,R ([Fig. 11]B), an extra branch arises from the tibial nerve as a separate (fourth) division; it enters the medial head of M. flexor perforatus digiti IV and also gives off a twig that anastomoses with the posterior division (left leg) or with the first branch of the posterior division (right leg). In T.p. 3R ([Fig. 11]B), a large extra branch arises from the proximal part of the medial division and passes medial and then deep to the medial head of M. flexor perforatus digiti III, perforates the tendinous part of the medial head of M. flexor perforatus digiti II, and joins the posterior division (lateral to the medial head of M. flexor perforatus digiti III). A similar branch is found in T.p. 3L except that it arises from the proximal part of the posterior (rather than the medial) division. In T.p. 3R ([Fig. 11]B), the branch to M. gastrocnemius pars externa arises so far proximally that it appears as a separate (fifth) division of the tibial nerve. In two legs, the branch of the medial division that supplies M. gastrocnemius pars media sends a twig into the distal end of M. femorocruralis ([Fig. 11]A).
T. cupido
Individual Variation.—In one leg, an extra branch of the medial division arises immediately distal to the branch to M. gastrocnemius pars media and enters the proximal end of the medial head of M. flexor perforatus digiti III. In one instance, the branch to M. gastrocnemius pars interna passes through a gap in the origin of M. plantaris rather than distal to the origin of the latter.
P. p. jamesi
Individual Variation.—The branch to M. gastrocnemius pars interna gives a minute twig to the deep surface of the free belly of M. plantaris in one leg.
