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Extensor hallucis brevis muscle

The extensor hallucis brevis (EHB) is a small, flat muscle located on the dorsum of the foot. It arises from the superolateral surface of the calcaneus and runs obliquely forward to insert on the proximal phalanx of the great toe. It lies just medial to the extensor digitorum brevis and lateral to the extensor hallucis longus tendon, assisting in extension of the great toe at the metatarsophalangeal joint.

EHB is clinically significant because its tendon may be mistaken for a split tendon of the extensor hallucis longus. It may also be affected by trauma, tendon tears, or space-occupying lesions on the dorsum of the foot.

Synonyms

  • Short extensor of the great toe

  • Brevis extensor hallucis

Origin, Course, and Insertion

  • Origin: Superolateral surface of calcaneus, lateral talocalcaneal ligament, and inferior extensor retinaculum

  • Course: Fibers run obliquely forward and medially across the dorsum of the foot

  • Insertion: Dorsal aspect of the base of the proximal phalanx of the great toe

Tendon Attachments

  • Runs medial to the extensor digitorum brevis tendons

  • Inserts on the dorsum of the proximal phalanx of the hallux

  • Variations: May blend with the extensor hallucis longus tendon

Relations

  • Superiorly: Extensor hallucis longus tendon

  • Inferiorly: Dorsal surface of the calcaneus and talus

  • Medially: First metatarsal and great toe

  • Laterally: Extensor digitorum brevis

Nerve Supply

  • Deep fibular (peroneal) nerve (L5–S1)

Arterial Supply

  • Dorsalis pedis artery (branch of anterior tibial artery)

Venous Drainage

  • Dorsalis pedis vein draining into the anterior tibial vein

Function

  • Extension of hallux: Extends proximal phalanx of the great toe at the metatarsophalangeal joint

  • Synergist muscle: Assists extensor hallucis longus in hallux extension

  • Clinical marker: Helps differentiate between EHB and EHL tendon injuries on imaging

Clinical Significance

  • Tendon variations: May be mistaken for split EHL tendon on imaging or surgery

  • Injury: Vulnerable to trauma, lacerations, or strain on the dorsum of the foot

  • Masses: Hypertrophy or accessory slips may simulate a soft-tissue tumor

  • Imaging relevance: MRI is useful for identifying tears, tendon variants, and accessory slips

MRI Appearance

  • T1-weighted images:

    • Normal muscle: intermediate signal

    • Tendon: low signal (dark band)

    • Tears or inflammation: focal hyperintensity or tendon discontinuity

  • T2-weighted images:

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

    • Normal tendon: uniformly dark

    • Pathology: tendinopathy or partial tear shows bright hyperintense signal within tendon or sheath

  • STIR:

    • Muscle: intermediate-to-dark

    • Pathology: bright hyperintensity from edema, strain, or peritendinitis

  • Proton Density Fat-Saturated (PD FS):

    • Normal muscle: intermediate-to-dark signal

    • Tendon: sharply dark

    • Tears: bright signal clefts within tendon substance

    • Excellent for detecting subtle tears or accessory tendon slips

  • T1 Fat-Sat Post-Contrast:

    • Normal tendon: minimal or no enhancement

    • Inflammatory conditions: tendon sheath or adjacent tissues enhance

    • Postsurgical or scar tissue: enhancing; recurrent tear: non-enhancing gap

CT Appearance

Non-Contrast CT:

  • Muscle appears as soft tissue density on dorsum of foot

  • Tendon visible as fine linear density extending to proximal phalanx

  • Chronic tendinopathy may cause tendon thickening or calcifications

Post-Contrast CT (standard):

  • Muscle enhances homogeneously

  • Inflammation or synovitis around tendon may show soft-tissue enhancement

  • Tears: tendon gap may be visualized indirectly if surrounded by fluid density

MRI image

Extensor hallucis brevis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Extensor hallucis brevis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI image

Extensor hallucis brevis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002

MRI image

Extensor hallucis brevis muscle coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Extensor hallucis brevis muscle satital ct image