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Extensor hallucis brevis tendon

The extensor hallucis brevis (EHB) tendon is the short extensor tendon of the great toe, formed by the upper part of the extensor hallucis brevis muscle, located on the dorsum of the foot. It lies deep and lateral to the extensor hallucis longus tendon and provides dynamic extension to the metatarsophalangeal (MTP) joint of the hallux.

The EHB tendon is a key stabilizer during the early stance and push-off phases of gait, ensuring controlled toe extension and balance. It is particularly important for fine motor control of the hallux and assists the extensor hallucis longus (EHL) in coordinated toe elevation.

Synonyms

  • Short extensor tendon of the great toe

  • Dorsal short extensor of hallux

Origin, Course, and Insertion

  • Origin: From the superior and anterolateral surface of the calcaneus, lateral to the sinus tarsi, and from the inferior extensor retinaculum (as part of the extensor digitorum brevis complex)

  • Course: Fibers run obliquely forward and medially across the dorsum of the foot, forming a short thick tendon

  • Insertion: Onto the dorsal aspect of the base of the proximal phalanx of the great toe, lateral to the tendon of the extensor hallucis longus

Tendon Attachments

  • The EHB tendon passes deep to the superior and inferior extensor retinacula

  • It inserts into the proximal phalanx of the hallux, forming the medial part of the extensor expansion

  • Works synergistically with the EHL tendon to extend the great toe at the MTP joint

Relations

  • Superiorly: Skin and superficial fascia of the dorsum of the foot

  • Inferiorly: Dorsal aspect of the tarsal bones and extensor digitorum brevis

  • Medially: Extensor hallucis longus tendon

  • Laterally: Tendons of the extensor digitorum longus

  • Posteriorly: Dorsal surface of the calcaneus

Nerve Supply

  • Deep fibular (peroneal) nerve (L5–S1), branch of the common fibular nerve

Arterial Supply

  • Dorsalis pedis artery and its branches, primarily the lateral tarsal and arcuate arteries

Venous Drainage

  • Dorsal venous network of the foot, draining into the anterior tibial vein

Function

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

  • Assists EHL: Contributes to dorsiflexion of the hallux and stabilization of the first ray

  • Dynamic balance: Maintains dorsal foot stability during gait

  • Fine control: Provides subtle adjustments in toe extension during standing and walking

Clinical Significance

  • Tendinopathy: Common in overuse conditions such as running, jumping, or dancing

  • Traumatic tears: May occur in forced plantarflexion or direct trauma to dorsum of foot

  • Ganglion cysts: Can arise adjacent to the EHB tendon sheath

  • Post-surgical importance: Acts as a key anatomical landmark during dorsal foot procedures and hallux surgeries

  • Imaging relevance: MRI is the modality of choice for tendon integrity, partial tears, or peritendinitis

MRI Appearance

  • T1-weighted images:

    • Tendon: low signal (dark linear band) with uniform thickness

    • Muscle origin (EHB): intermediate signal intensity

    • Adjacent fat planes appear bright, helping delineate the tendon

    • Partial tear: focal intermediate-to-bright signal with loss of linear continuity

  • T2-weighted images:

    • Normal tendon: dark low-signal structure against intermediate muscle background

    • Muscle belly: intermediate-to-low signal, slightly darker than on T1

    • Pathology: bright focal signal indicating tendinopathy, inflammation, or partial tear

    • Fluid around tendon sheath appears hyperintense

  • STIR:

    • Normal tendon: dark linear appearance

    • Normal muscle: intermediate-to-dark signal intensity

    • Pathology (tendinitis, strain, edema): bright hyperintense signal in tendon sheath or myotendinous junction

  • Proton Density Fat-Saturated (PD FS):

    • Normal tendon: uniformly dark, sharply defined

    • Muscle: intermediate-to-dark homogeneous signal

    • Pathology: bright hyperintense regions within tendon (partial tear, peritendinitis, or reactive edema)

    • Best sequence for assessing subtle fiber disruption and peritendinous fluid

  • T1 Fat-Sat Post-Contrast:

    • Normal tendon: no significant enhancement

    • Tendinitis or tenosynovitis: shows focal or diffuse enhancement

    • Chronic degeneration: peripheral rim enhancement around low-signal fibrotic tissue

CT Appearance

Non-Contrast CT:

  • Tendon: soft-tissue density; appears as a thin band across dorsum of the foot

  • Muscle belly: visible as a small soft-tissue structure lateral to EHL

  • Chronic tendinopathy: may show subtle thickening or peritendinous calcifications

Post-Contrast CT (standard):

  • Tendon sheath enhancement in cases of inflammation or tenosynovitis

  • Muscle and tendon both enhance uniformly under normal conditions

  • Useful for assessing calcific changes, ossifications, or postoperative anatomy

MRI image

Extensor hallucis brevis tendon of the Foot axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Extensor hallucis brevis tendon of the Foot axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI image

Extensor hallucis brevis tendon of the Foot axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002

MRI image

Extensor hallucis brevis tendon of the Foot axial cross sectional anatomy 3T MRI AI enhanced radiology image

MRI image

Extensor hallucis brevis tendon of the Foot coronal cross sectional anatomy 3T MRI AI enhanced radiology image

CT image

Extensor hallucis brevis tendon ct axial 1

CT image

Extensor hallucis brevis tendon ct axial