Lumbricals of foot

The lumbricals of the foot (Latin: musculi lumbricales pedis) are four small intrinsic muscles of the foot. They belong to the central compartment (middle group) of the plantar foot muscles. The name of these muscles comes from the Latin word lumbricus which means "worm" because the lumbricals have a worm-like appearance.

Lumbricals of foot
OriginTendons of flexor digitorum longus muscle
Insertion Extensor expansions of toes 2 - 5
Action

Flexion of toes at 2nd - 5th metatarsoophalangeal joints

Extension of toes at 2nd - 5th interphalangeal joints

Innervation

Lumbrical I - medial plantar nerve (C2 - S3)

Lumbricals II, III, IV - lateral plantar nerve (S2 - S3)

Blood supply Medial and lateral plantar arteries

Origin

The lumbrical muscles arise from the tendons of the flexor digitorum longus muscle.

Insertion

The lumbricals insert at the extensor expansions of the second to fifth fingers of the foot.

Action

The lumbricals provide toe flexion at the second to fifth metatarsophalangeal joints. Also, they extend toes at the second to fifth interphalangeal joints.

Innervation

The first lumbrical is innervated by the medial plantar nerve (S2 - S3), while the rest of the lumbricals receive nerve supply from the lateral plantar nerve (S2 - S3). Both are terminal branches of the tibial nerve.

Blood supply

The lumbricals of the foot receive arterial blood supply from the lateral and medial plantar arteries. Both are terminal branches of the posterior tibial artery.