Part 46

Insertion.—It becomes tendinous about the middle third of the metatarsus. Extending down the anterior face of the metatarsus it is inserted to the inner tubercle of the base of the first phalanx of the outer or fourth toe.

Shape.—Long, slender.

Relations.—Posteriorly with the metatarsus.

Action.—Pulls the fourth toe upward and inward.

=Flexor Hallucis Brevis.= Location.—Postero-internal side of the metatarsus.

Origin.—Side and lower margin of the inner aspect of the hypotarsus of the tarso-metatarsus and from the shaft of this bone immediately below it.

Insertion.—Winds round inner side of basal joint of the hallux and is inserted on its under side.

Shape.—Small flat muscle gradually tapering into a tendon.

Relations.—Posteriorly with the metatarsus.

Action.—To flex the hallux.

=Extensor Annularis Brevis.= Location.—On postero-external side of metatarsus.

Origin.—External aspect of the hypotarsus and the shaft below.

Insertion.—Supero-external part of the basal phalanx of the fourth toe.

Shape.—Small flat muscle.

Relations.—Posteriorly with the metatarsus.

Action.—Extensor of the fourth toe.

=Tibialis Posticus= (Fig. 24, No. 23). Location.—In the posterior tibial region.

Origin.—From the whole shaft of the fibula below the insertion of the biceps flexor cruris, and from the shaft of the tibia a short distance below this insertion. Also from the interosseous membrane, and the adjacent surface of the tibial shaft.

Insertion.—Passing in front of the external malleolus, crossing the ankle-joint, finally inserted into the outer edge of the summit of the tarso-metatarsal bone.

Shape.—Long, subcylindrical.

Relations.—Medially, with the flexor perforans digitorum pedis; superiorly, with the postero-external portion of the tibia.

Action.—Extends the metatarsus upon the tibia.

=Flexor Perforatus Indicis Secundus Pedis= (Fig. 17, No. 5). Location.—The posterior tibial region.

Origin.—From the external surface of the outer condyle of the femur, just below the head of the gastrocnemius.

Insertion.—Passing in an oblique manner along posterior to the tibia, extends through the superficial part of the tibial cartilage to the outer side of the leg; then crossing the tibio-tarsal joint, it passes through a special canal of the hypotarsus, down the back of the tarso-metatarsus, under the annular ligament of the sole of the foot and a cartilaginous structure below this ligament, over the trochlea, and is inserted to the middle shaft of the second phalanx of the second toe.

Shape.—Thin, flat, broadly spindle-shaped.

Relations.—Posteriorly, with the flexor perforatus medius secundus pedis, and anteriorly, with the flexor perforatus annularis primus pedis.

Action.—Flexes the toes.