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Oblique head of adductor hallucis muscle

The oblique head of the adductor hallucis muscle is a deep intrinsic muscle of the sole of the foot, forming part of the third muscular layer along with the flexor hallucis brevis. It plays a key role in adducting the great toe, stabilizing the first metatarsophalangeal (MTP) joint, and maintaining the transverse arch of the foot.

It arises from the bases of the second to fourth metatarsals and the sheath of the fibularis longus tendon, and it joins the transverse head to insert via a common tendon into the lateral side of the base of the proximal phalanx of the hallux. Its deep position and relationship to the plantar vessels make it clinically and surgically important during reconstructive and vascular procedures involving the plantar arch.

Synonyms

  • Oblique adductor of the great toe

  • Adductor hallucis obliquus

Origin, Course, and Insertion

  • Origin: Bases of the second, third, and fourth metatarsal bones; sheath of the fibularis (peroneus) longus tendon; and the plantar aspect of the cuboid

  • Course: Fibers run obliquely medially and anteriorly across the sole of the foot, converging to form a tendon that joins the transverse head of adductor hallucis

  • Insertion: Lateral side of the base of the proximal phalanx of the great toe, along with the lateral sesamoid bone and the common adductor tendon

Tendon Attachments

  • Inserts via a common tendon (shared with the transverse head) into the lateral sesamoid and lateral base of the proximal phalanx

  • The fibular sesamoid bone acts as a pulley for the tendon during toe adduction

  • Closely associated with the lateral plantar artery and deep plantar arch

Relations

  • Superiorly: Deep plantar vessels and nerves

  • Inferiorly: Plantar aponeurosis and subcutaneous fat

  • Medially: Flexor hallucis brevis and medial sesamoid

  • Laterally: Transverse head of adductor hallucis and plantar interossei muscles

  • Posteriorly: Deep branch of the lateral plantar artery and nerve

  • Anteriorly: First metatarsophalangeal joint capsule

Nerve Supply

  • Deep branch of the lateral plantar nerve (from tibial nerve, roots S2–S3)

Arterial Supply

  • Deep plantar arch (from lateral plantar artery)

  • Contributions from medial plantar artery and first plantar metatarsal artery

Venous Drainage

  • Deep plantar venous arch and medial plantar veins, draining into the posterior tibial vein

Function

  • Adduction of the great toe: Draws the hallux toward the second toe

  • Transverse arch support: Maintains the integrity of the metatarsal arch during stance and propulsion

  • Joint stabilization: Supports the first MTP joint during gait and push-off

  • Synergistic activity: Works with flexor hallucis brevis and abductor hallucis for dynamic control of the hallux

Clinical Significance

  • Overuse strain: Common in athletes or dancers; may cause plantar midfoot pain

  • Nerve entrapment: Compression of deep branch of the lateral plantar nerve can cause focal weakness and tenderness in the deep sole

  • Surgical relevance: Important landmark during plantar arch or neuroma surgery

  • Imaging importance: Assessed for muscle strain, tear, denervation, or atrophy in chronic neuropathies (tarsal tunnel syndrome, diabetic neuropathy)

MRI Appearance

  • T1-weighted images:

    • Normal muscle: intermediate signal intensity with visible fascicular pattern

    • Tendon: low signal (dark band) joining the lateral sesamoid and proximal phalanx

    • Fatty intermuscular planes: bright signal separating it from adjacent muscles

    • Muscle atrophy (in neuropathy): increased signal intensity (fatty infiltration)

  • T2-weighted images:

    • Normal muscle: intermediate-to-low signal, darker than on T1

    • Tendon: uniformly low signal

    • Pathology: bright hyperintense areas representing strain, partial tear, or inflammation

    • Chronic denervation: diffuse high T2 signal followed by muscle atrophy

  • STIR:

    • Normal muscle: intermediate-to-dark signal intensity

    • Acute strain or inflammation: bright hyperintense regions within muscle belly or tendon

    • Surrounding fascial edema or fluid: high signal intensity

  • Proton Density Fat-Saturated (PD FS):

    • Normal: intermediate-to-dark homogeneous muscle signal

    • Pathologic: focal bright hyperintensity indicating muscle edema, strain, or partial tear

    • Denervation edema: diffuse bright signal across muscle belly

  • T1 Fat-Sat Post-Contrast:

    • Normal: mild uniform enhancement

    • Inflammation, tendinitis, or postoperative change: shows focal enhancement at tendon or myotendinous junction

    • Chronic fibrosis: peripheral rim enhancement with central low signal

CT Appearance

Non-Contrast CT:

  • Muscle: soft-tissue density in deep plantar layer

  • Tendon: fine linear soft-tissue structure inserting onto base of proximal phalanx

  • Adjacent sesamoid: dense ovoid bone lateral to first metatarsal head

  • Chronic changes: calcification or atrophy in long-standing neuropathy

Post-Contrast CT (standard):

  • Muscle enhances uniformly

  • Areas of inflammation, fibrosis, or peritendinous thickening show increased enhancement

  • Useful in identifying postoperative fibrosis, chronic tendinopathy, or atrophic muscle changes

MRI images

oblique head of Adductor hallucis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI images

oblique head of Adductor hallucis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002

MRI image

oblique head of Adductor hallucis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

oblique head of Adductor hallucis muscle coronal ct image