Lower limb

Lumbrical muscles of the foot

Musculi lumbricales pedis

Origin

Tendons of flexor digitorum longus, at the level of the midfoot

Insertion

Medial side of the base of the proximal phalanx and the dorsal extensor expansion of toes 2 to 5

Function

Flex the MTP joints while simultaneously extending the IP joints of toes 2-5

Innervation

1st lumbrical: medial plantar nerve; 2nd-4th lumbricals: lateral plantar nerve (both branches of the tibial nerve)

Movement & chain

Together with the interossei, produce a controlled 'toe-off' during the push-off phase of the gait cycle, by extending the toes while the ball of the foot is still loaded.

Palpation

Located in the deep central plantar foot arising from the FDL tendons; not individually palpable.

Clinical

Coordinate MTP flexion with IP extension; loss of intrinsic function in diabetic neuropathy produces claw toe deformities.

Segmental innervation

Tibial nerve, S1-S2 (via the plantar nerves).

In clinical practice

Diabetic foot inspection and pressure ulcer prevention; monitor for friction points from footwear or bedding and ensure correct anti-embolism stocking fit.

Region in the model

Lower limb