INSERTION.--The common belly terminates approximately two thirds of the way down the shank; the slender ossified tendon begins along the posteromedial edge of the common belly, continues distally along the posterior surface of the shank, and becomes flexible before passing through the canal in the tibial cartilage that lies posteromedial to the canal for M. flexor digitorum longus. The tendon passes with the tendon of M. flexor perforatus digiti II (medial to the latter) through a canal in the hypotarsus (see M. flexor perforatus digiti II); just below the hypotarsus, the tendon becomes superficial to the tendon of M. flexor perforatus digiti II and farther distally becomes lateral and finally deep to the latter; the tendon is ossified for most of the length of the tarsometatarsus. At the distal end of this bone, the tendon expands before passing onto the ventral surface of digit II between the tendons of Mm. flexor perforatus digiti II and flexor digitorum longus; at the level of the first phalanx, the edges of the tendon extend dorsally around the tendon of M. flexor digitorum longus and fuse, forming a sheath around the latter; the latter emerges from the sheath near the distal end of the first phalanx; the tendon attaches to the proximal end of the subarticular cartilage ventral to the first interphalangeal joint (the strongest attachment is on the medial side). INNERVATION.--The lateral division of the tibial nerve sends twigs into the posteromedial edge of the posterior head. INDIVIDUAL VARIATION.--In one leg, the fleshy part of the anterior head is unusually long. In another leg, the anterior head is entirely tendinous. In one leg, a bundle of fibers of the posterior head attaches to the deep surface of the distal part of the patellar tendon. In one leg, near the middle of the tarsometatarsus a rather long and narrow but thick and strong vinculum arises from the tendon of M. flexor perforatus digiti II and, farther distally, joins the tendon of M. flexor perforans et perforatus digiti II. _T. cupido_ INDIVIDUAL VARIATION.--In one leg, the posterior head arises in part from the distolateral edge of the patellar tendon and in another, in part from the superficial surface of the distolateral corner of the patellar tendon. _P. p. jamesi_ INDIVIDUAL VARIATION.--None of significance. =_M. Flexor Perforans et Perforatus Digiti III_=, Figs. 12, 14 _T. pallidicinctus_