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Transverse head of adductor hallucis muscle

The transverse head of the adductor hallucis is one of two heads of the adductor hallucis muscle — the other being the oblique head. It lies in the third layer of the sole, deep to the plantar aponeurosis and flexor tendons. This head forms a horizontal band across the forefoot, connecting the plantar ligaments of the metatarsophalangeal (MTP) joints.

The transverse head plays a vital role in adduction of the great toe, stabilization of the forefoot, and maintenance of the transverse metatarsal arch. It is an important structure in gait dynamics and forefoot biomechanics, especially during toe-off.

Synonyms

  • Transverse part of adductor hallucis

  • Transverse head of the great toe adductor

Origin, Course, and Insertion

  • Origin: Plantar ligaments of the third, fourth, and fifth metatarsophalangeal joints, and deep transverse metatarsal ligament

  • Course: Fibers run medially and obliquely across the metatarsal heads toward the great toe

  • Insertion: Lateral side of the base of the proximal phalanx of the great toe via the lateral sesamoid bone, where it joins the tendon of the oblique head of adductor hallucis

Tendon Attachments

  • Joins the tendon of the oblique head of adductor hallucis near the lateral sesamoid bone

  • Inserts into the lateral side of the base of the proximal phalanx of the hallux

  • Connects with the deep transverse metatarsal ligament, stabilizing the metatarsal heads

Relations

  • Superiorly: Plantar ligaments of MTP joints and interosseous muscles

  • Inferiorly: Plantar aponeurosis

  • Medially: Oblique head of adductor hallucis

  • Laterally: Flexor digiti minimi brevis and lateral plantar vessels

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

Nerve Supply

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

Arterial Supply

  • Deep plantar arch, formed by the lateral plantar artery and the deep plantar branch of the dorsalis pedis artery

Venous Drainage

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

Function

  • Adduction of the great toe: Pulls the hallux medially toward the second toe

  • Transverse arch support: Maintains integrity of the forefoot’s transverse arch

  • Stabilization: Reinforces the MTP joints during toe-off

  • Dynamic balance: Assists in distributing plantar pressure during propulsion

Clinical Significance

  • Forefoot pain: Overuse or strain may cause metatarsalgia

  • Hallux valgus: Weakness or imbalance may contribute to lateral deviation of the hallux

  • Flatfoot deformity: Loss of transverse arch support increases stress on this muscle

  • Nerve entrapment: Compression of deep branch of lateral plantar nerve may reduce adductor strength

  • Surgical relevance: Important in bunion correction and sesamoid alignment procedures

MRI Appearance

  • T1-weighted images:

    • Muscle: intermediate signal intensity, clearly separable from surrounding fat

    • Tendon: low signal (dark linear band) near lateral sesamoid and proximal phalanx

    • Fat around muscle appears bright, enhancing anatomical contrast

  • T2-weighted images:

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

    • Tendon: uniformly low signal

    • Pathology: hyperintense foci at tendon or myotendinous junction indicating strain or partial tear

    • Surrounding edema or inflammatory change: localized bright hyperintensity

  • STIR:

    • Normal: intermediate-to-dark signal intensity

    • Pathologic changes: bright hyperintense signal in cases of edema, inflammation, or muscle injury

    • Useful for identifying early interstitial edema or denervation changes

  • Proton Density Fat-Saturated (PD FS):

    • Normal: intermediate-to-dark signal, homogeneous appearance

    • Pathology: bright linear or patchy hyperintensity suggesting tendinitis or tear

    • Accurately depicts peritendinous fluid or inflammatory changes near the lateral sesamoid

  • T1 Fat-Sat Post-Contrast:

    • Normal: mild homogeneous enhancement

    • Inflamed tendon sheath or fascia: focal or diffuse enhancement

    • Chronic tendinopathy: rim enhancement with central low-signal fibrosis

CT Appearance

Non-Contrast CT:

  • Muscle: uniform soft-tissue density crossing transversely over metatarsal heads

  • Tendon: faint linear soft-tissue density extending to base of proximal phalanx

  • Sesamoid bone: dense, ovoid ossicle at the first metatarsal head

  • Chronic pathology: sclerosis or irregularity at lateral sesamoid or metatarsal heads

Post-Contrast CT (standard):

  • Muscle: enhances homogeneously

  • Inflamed peritendinous or intermetatarsal tissue: shows focal enhancement

  • Useful for evaluating postoperative scarring, fibrosis, or soft-tissue mass effect in the forefoot

MRI images

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

MRI images

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

MRI images

Transverse head of Adductor hallucis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00003

MRI image

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

CT image

Transverse head of Adductor hallucis muscle ct axial