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Extensor digitorum longus muscle

The extensor digitorum longus (EDL) is one of the four muscles of the anterior compartment of the leg. It lies lateral to the tibialis anterior and contributes tendons to the second through fifth toes. Its strong tendonous slips extend across the dorsum of the foot, enabling extension of the toes and assisting in dorsiflexion of the foot at the ankle.

The EDL is clinically relevant in anterior compartment syndromes, tendon injuries, and foot deformities. On imaging, it can be assessed for muscle trauma, denervation, or compartment pathology.

Synonyms

  • EDL muscle

  • Long toe extensor muscle

  • Extensor digitorum longus of the leg

Origin and Insertion

  • Origin: Lateral condyle of tibia, superior three-quarters of medial fibular surface, and interosseous membrane

  • Course: Descends along the anterior leg, lateral to tibialis anterior, forming a tendon at the ankle that passes beneath the superior and inferior extensor retinacula

  • Insertion: Tendon divides into four slips inserting onto the middle and distal phalanges of the second through fifth toes

Nerve Supply

  • Deep peroneal (fibular) nerve (L4–L5)

Arterial Supply

  • Anterior tibial artery

Venous Drainage

  • Drains into anterior tibial vein → popliteal vein

Function

  • Extension of toes 2–5 at metatarsophalangeal and interphalangeal joints

  • Assists in dorsiflexion of the foot at the ankle

  • Contributes to eversion of the foot

MRI Appearance

T1-weighted images:

  • Normal muscle shows low-to-intermediate signal intensity

  • Fatty septa and surrounding subcutaneous fat are bright

T2-weighted images:

  • Muscle shows low-to-intermediate baseline signal

  • Injury, edema, or inflammation appear as bright areas

STIR (Short Tau Inversion Recovery):

  • Normal muscle: low-to-intermediate signal

  • Pathology (strain, inflammation, compartment syndrome): bright hyperintensity

Proton Density Fat-Saturated (PD FS):

  • Normal muscle: low-to-intermediate signal

  • Acute injuries, tendinopathy, or edema: bright signal

T1 Fat-Sat Post-Contrast:

  • Normal muscle: mild homogeneous enhancement

  • Infection or tumor: heterogeneous or focal enhancement

  • Abscess: peripheral rim enhancement with central low signal

CT Appearance (Axial)

Non-Contrast CT:

  • Muscle appears as a soft tissue density structure in the anterior leg compartment, lateral to tibialis anterior and medial to peroneus longus

  • Separated from other muscles by thin fat planes and fascial boundaries

  • Normal muscle: homogeneous density

  • Hemorrhage: hyperdense

  • Chronic atrophy: low-density fatty replacement

Post-Contrast CT:

  • Normal muscle: mild homogeneous enhancement

  • Inflammation or infection: increased enhancement with adjacent fat stranding

  • Tumors: heterogeneous or nodular enhancement

  • Abscess: central hypodensity with peripheral rim enhancement

MRI image

Extensor digitorum longus muscle sag cross sectional anatomy 3T radiology anatomy image-img-00000-00000

MRI image

extensor digitorum longus muscle anatomy 3t mri image

MRI image

extensor digitorum longus

CT image

Extensor digitorum longus muscle axial ct image 1

CT image

Extensor digitorum longus muscle axial ct image 2

CT image

Extensor digitorum longus muscle axial ct image

MRI image

Extensor digitorum longus muscle MRI sag cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Extensor digitorum longus muscle MRI sag cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

CT image

Extensor digitorum longus muscle ct axial