Transverse head of adductor hallucis

At a glance

English

Transverse head of adductor hallucis

Latin (TA2)

Caput transversum adductoris hallucis

System

Muscle

Region

Lower limb

Side

Paired, left and right

Inserts on

The fifth metatarsal bone, fourth metatarsal bone and third metatarsal bone

About the transverse head of adductor hallucis

Adductor hallucis has two heads in the third layer of the sole, and the transverse head is the smaller and more forward. Once called transversus pedis, it is a thin, flat band running straight across the foot just behind the bases of the toes, under the heads of the metatarsals. It lies deep to the long flexor tendons and the lumbricals.

Its fibres arise from the plantar ligaments, or plantar plates, of the metatarsophalangeal joints of toes three to five, and from the deep transverse metatarsal ligament between them. Sometimes only the third and fourth joints contribute. The fibres run medially across the sole and blend with the tendon of the oblique head, attaching with it to the outer side of the proximal phalanx base of the great toe through the lateral sesamoid bone.

The head pulls the great toe towards the second toe and helps hold the metatarsal heads together. Because it spans the front of the foot from side to side, it acts as a living tie for the transverse arch, resisting spreading of the forefoot when weight comes onto the ball of the foot. It is most active during push-off and when the forefoot must stay compact on uneven ground.

It is supplied by the deep branch of the lateral plantar nerve and receives blood from the plantar metatarsal arteries arising from the deep plantar arch. Along with the oblique head, it is part of the soft tissue balance around the first metatarsophalangeal joint that is disturbed in hallux valgus; surgeons sometimes release the adductor tendon to help correct that deformity. The head is small and occasionally absent.

Attachments, action and supply

Origin

Plantar ligaments of the third to fifth metatarsophalangeal joints and the deep transverse metatarsal ligament.

Insertion

Outer side of the proximal phalanx base of the great toe, blended with the oblique head and the lateral sesamoid.

Action

Adducts the great toe and helps hold the metatarsal heads together, supporting the transverse arch.

Nerve supply

Deep branch of the lateral plantar nerve (S2, S3).

Blood supply

Plantar metatarsal arteries from the deep plantar arch.