Adductor hallucis Muscle (Adductor obliquus hallucis) arises by two heads—oblique and transverse and is responsible for adducting the big toe. It has two heads, both are innervated by the lateral plantar nerve.
Adductor hallucis is a two-headed, intrinsic muscle of the sole of the foot. Among the three vertical groups of plantar foot muscles (lateral, central and medial), adductor hallucis muscle functionally belongs to the medial group of plantar foot muscles. However, it is anatomically located within the central compartment of foot.
Foot muscles are also divided horizontally into four layers from superficial to deep. In that classification, adductor hallucis comprises the third layer of plantar foot muscles, together with the flexor hallucis brevis and flexor digiti minimi Brevis.
Structure of Adductor Hallucis Muscle
Oblique head
The oblique head is a large, thick, fleshy mass, crossing the foot obliquely and occupying the hollow space under the first, second, third and fourth metatarsal bones.
It arises from the bases of the second, third, and fourth metatarsal bones, and from the sheath of the tendon of the Peronæus longus, and is inserted, together with the lateral portion of the Flexor hallucis brevis, into the lateral side of the base of the first phalanx of the great toe.
Transverse head
The transverse head (Transversus pedis) is a narrow, flat fasciculus which arises from the plantar metatarsophalangeal ligaments of the third, fourth, and fifth toes (sometimes only from the third and fourth), and from the transverse ligament of the metatarsals.
It is inserted into the lateral side of the base of the first phalanx of the great toe, its fibers blending with the tendon of insertion of the oblique head.
Origin and insertion
Adductor hallucis consists of the two heads; oblique and transverse. They have different origins, but share a common insertion.
The oblique head consists of lateral and medial parts. Both parts originate from the bases of metatarsal bones 2-4, cuboid, lateral cuneiform bones and tendon of fibularis longus. They both then course anteromedially, with the medial part blending with the tendon of flexor hallucis brevis on the lateral sesamoid bone of great toe. The lateral part meets with the tendon of the transverse head of adductor hallucis.
The transverse head originates as three bands from the plantar metatarsophalangeal ligaments of toes 3-5 and deep transverse metatarsal ligaments located between the respective toes. The bands course medially and fuse into a unique muscle belly which inserts together with the oblique head into the lateral surface of the base of proximal phalanx of great toe.
Note that the transverse head is quite variable; sometimes it might be absent, while in other situations it can attach to the first metatarsal bone and comprise the opponens hallucis muscle.
Oblique and Transverse Head of Adductor Hallucis Muscle
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The adductor hallucis has two heads, an oblique head, and a transverse head
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Origin: The oblique head originates at the proximal ends of the metatarsals two thourgh four, and the transverse head originates via MTP ligaments of digits three through five
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Insertion: inserts at the proximal phalanx of the great toe
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Action: The primary action is to adduct the great toe
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Blood Supply: First plantar metatarsal artery
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Innervation: Deep branch of lateral plantar
Nerve Supply of
Adductor hallucis is innervated by the deep branch of lateral plantar nerve (S2, S3), which stems from the tibial nerve.
Blood Supply
The main vascular source for this muscle is the posterior tibial artery with its branches;
- Deep branches of medial plantar artery
- Lateral plantar artery and its branches; deep plantar arch and plantar metatarsal arteries 1-4
Function
Adductor hallucis muscle has two actions at the first metatarsophalangeal joint;
- It adducts the great toe, i.e. pulls it towards the foot’s midline.
- Together with flexor hallucis longus, it flexes the great toe.
These actions play important roles in the terminal stance phase of the gait cycle. By flexing and adducting the big toe, adductor hallucis reinforces the forefoot as the center of gravity for the body weight before the heel lifts up. In addition, due to the horizontal position of its transverse head, it stabilizes the foot arches and fixes the forefoot.
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