Interosseous muscle III

The interosseous muscle III is one of the interosseous muscles of the foot, located on the palmar surface of the metatarsal III. This group of muscles has a very different arrangement depending on the species.

Conformation: It is a long penniform muscle along the ventral surface of the metatarsal III.

Origin: On the proximal end of the metatarsal III and on the nearby tarsal structures.

Insertion: On the proximal sesamoid bones.

Vascularization: Palmar metacarpal arteries.

Variations:

• In equids, this muscle is the only functional interosseous muscle. There are two small remnants of the interosseous muscles II and IV corresponding to the reduced metatarsal bones II and IV in this species. This muscle is mainly fibrous with a few rare fleshy bundles. It originates at the end of the metatarsal III, but also partly originates at the tuberosity of tarsal bone IV and on the palmar surface of the calcaneus. It inserts on the external surfaces of the proximal sesamoid bones and gives two stripes that extend towards the dorsal surface of the toe to join the tendon of the extensor digitalis longus muscle.