Abductor digiti minimi of foot

At a glance

English

Abductor digiti minimi of foot

Latin (TA2)

Abductor digiti minimi pedis

System

Muscle

Region

Lower limb

Side

Paired, left and right

About the abductor digiti minimi of foot

This muscle lies in the first, most superficial layer of the sole, along its lateral border, where it forms much of the soft ridge on the outer side of the foot. Its counterpart in the upper limb is the abductor of the little finger in the hand. Along its inner edge run the lateral plantar nerve and vessels.

It has a wide origin at the back of the sole. Fibres come from both the lateral and medial processes of the calcaneal tuberosity and from the bone between them, from the plantar aponeurosis above which it lies, and from the fibrous septum separating it from flexor digitorum brevis. The belly runs forwards along the outer edge of the foot. Its tendon slides over a smooth groove under the fifth metatarsal's base, then attaches with flexor digiti minimi brevis to the outer edge of the little toe's proximal phalanx at its base. Some deep fibres often end on the tuberosity of the fifth metatarsal and are sometimes named as a separate slip.

The muscle abducts the little toe and flexes it at its metatarsophalangeal joint. In practice the abduction is slight; its larger role is to help support the lateral longitudinal arch and to brace the outer border of the foot while standing and walking.

Because it works constantly in upright posture it can be strained and sore in people who stand or run a great deal. The first branch of the lateral plantar nerve, which supplies this muscle, can be trapped near the heel, causing heel pain that is easily mistaken for plantar fasciitis. Where a sixth toe is present, the muscle may attach to it instead. The muscle is also used by surgeons as a small flap to cover defects of the heel.

Attachments, action and supply

Origin

Lateral and medial processes of the calcaneal tuberosity, the bone between them, the plantar aponeurosis and the adjacent intermuscular septum.

Insertion

Outer edge of the little toe's proximal phalanx at its base, together with flexor digiti minimi brevis.

Action

Abducts the little toe and flexes it at the metatarsophalangeal joint; supports the lateral longitudinal arch.

Nerve supply

Lateral plantar nerve, from the tibial nerve (S2, S3).

Blood supply

Lateral plantar artery and the plantar digital artery of the little toe.