Oblique head of adductor hallucis

At a glance

English

Oblique head of adductor hallucis

Latin (TA2)

Caput obliquum adductoris hallucis

System

Muscle

Region

Lower limb

Side

Paired, left and right

Arises from

The fourth metatarsal bone

About the oblique head of adductor hallucis

Adductor hallucis is a muscle of the third layer of the sole with two heads, oblique and transverse, that converge on the outer side of the great toe. The oblique head is by far the bulkier. It is a thick, fleshy mass that fills the hollow beneath the shafts of the lateral metatarsals and runs diagonally from the middle of the foot towards the base of the great toe.

It arises from the plantar surfaces of metatarsals two to four, near their bases, and from the fibrous sheath that holds the tendon of fibularis (peroneus) longus as it crosses the sole. Its fibres run forwards and medially. Near the great toe they join the lateral head of flexor hallucis brevis, and the combined tendon attaches, through the lateral sesamoid bone, to the outer side of the proximal phalanx base of the great toe. The transverse head joins the same tendon from the side.

The head draws the great toe towards the second toe, which counts as adduction in the foot because the reference line for toe movements runs along the second toe. It also helps flex the great toe at its base. Probably more important is its part in bracing the front of the foot: with the transverse head it ties the metatarsals together and supports the transverse arch during standing and push-off.

It lies deep, covered by the long flexor tendons, the lumbricals and flexor digitorum brevis, and its own deep surface rests against the interossei and the deep plantar arch. The deep branch of the lateral plantar nerve supplies it, along with the deep plantar arch and the plantar metatarsal arteries. Its pull is one of the forces that tilt the great toe outwards in hallux valgus, when the balance of muscles around the joint is lost.

Attachments, action and supply

Origin

Plantar surfaces of the bases of metatarsals two, three and four and the sheath of the fibularis longus tendon.

Insertion

Outer side of the proximal phalanx base of the great toe, through the lateral sesamoid and with the lateral head of flexor hallucis brevis.

Action

Adducts the great toe towards the second toe, assists flexion at its metatarsophalangeal joint and helps support the transverse arch.

Nerve supply

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

Blood supply

Deep plantar arch and plantar metatarsal arteries.