Origin: Tendons of flexor digitorum longus
Insertion: Medial aspect of extensor expansion over lateral four digits
Nerve: Plantar nerve
Action: Flex proximal phalanges and extend middle and distal phalanges of lateral four digits
The Lumbricales are four small muscles, accessory to the tendons of the Flexor digitorum longus and numbered from the medial side of the foot; they arise from these tendons, as far back as their angles of division, each springing from two tendons, except the first. The muscles end in tendons, which pass forward on the medial sides of the four lesser toes, and are inserted into the expansions of the tendons of the Extensor digitorum longus on the dorsal surfaces of the first phalanges.
Variations.—Absence of one or more; doubling of the third or fourth. Insertion partly or wholly into the first phalanges.