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Dorsal interossei tendons of foot

The dorsal interossei tendons are the terminal tendinous extensions of the dorsal interossei muscles, located in the fourth (deepest) layer of the foot, between the metatarsal bones. They form part of the dorsal group of intrinsic foot muscles, primarily responsible for abducting the toes (spreading them away from the 2nd digit) and assisting in flexion at the metatarsophalangeal (MTP) joints and extension at the interphalangeal joints.

There are four dorsal interossei muscles and tendons, each arising from adjacent sides of two metatarsals. The tendons insert onto the proximal phalanges and dorsal digital expansions, providing fine control of toe movement and contributing to metatarsal stability during gait.

Synonyms

  • Dorsal intermetatarsal tendons

  • Dorsal abductors of the toes

Origin, Course, and Insertion

  • Origin: From the adjacent sides of the metatarsal shafts of the 1st to 5th toes (two-headed origin between each pair of metatarsals)

  • Course: Fibers converge into tendons that pass distally over the interosseous spaces toward the bases of the proximal phalanges

  • Insertion:

    • First dorsal interosseous tendon: Inserts on the medial side of the proximal phalanx of the 2nd toe

    • Second to fourth dorsal interossei tendons: Insert on the lateral sides of the proximal phalanges of the 2nd, 3rd, and 4th toes respectively

    • Each tendon also contributes to the dorsal digital expansion (extensor hood)

Tendon Attachments

  • Tendons attach to the proximal phalangeal bases and blend with the extensor expansion

  • They pass beneath the deep transverse metatarsal ligament and are stabilized by intermetatarsal fascia

  • Function synergistically with the extensor digitorum longus and lumbricals to balance toe movement

Relations

  • Superficial: Dorsal fascia and extensor tendons (particularly extensor digitorum longus)

  • Deep: Interosseous fascia, plantar interossei muscles, and metatarsal bones

  • Medially: Tendons of extensor hallucis brevis

  • Laterally: Tendons of extensor digitorum brevis and adjacent neurovascular bundles

Nerve Supply

  • Lateral plantar nerve (deep branch, S2–S3) — all dorsal interossei tendons

  • Occasionally minor contribution from the deep fibular (peroneal) nerve to the first dorsal interosseous tendon

Function

  • Toe abduction: Abduct the toes away from the 2nd toe (reference line of the foot)

  • MTP joint flexion: Assist in flexion at metatarsophalangeal joints

  • Interphalangeal joint extension: Via insertion into extensor expansion

  • Foot stabilization: Maintain transverse arch of the foot

  • Dynamic balance: Fine-tune toe positioning during walking and running

Clinical Significance

  • Tendinopathy or strain: Overuse injuries common in athletes and dancers

  • Intermetatarsal bursitis: Adjacent inflammation may irritate dorsal interossei tendons

  • Morton’s neuroma association: Chronic irritation in the intermetatarsal space may mimic tendon pain

  • Muscle imbalance: Weakness can cause altered toe alignment or metatarsalgia

  • Surgical relevance: Dorsal interossei tendons are landmarks during dorsal foot surgery and nerve decompression

MRI Appearance

  • T1-weighted images:

    • Muscle bellies: intermediate signal intensity, clearly separated between metatarsals

    • Tendons: low signal (dark) linear structures inserting onto proximal phalanges

    • Fat between tendons: bright, enhancing contrast between fascicles

    • Partial tears: focal discontinuity or hyperintense gaps

  • T2-weighted images:

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

    • Tendons: very low signal (black) with uniform thickness

    • Pathology: bright hyperintense foci along tendons or at myotendinous junctions in cases of tendinopathy or strain

    • Intermetatarsal bursitis: bright signal between adjacent tendons

  • STIR:

    • Normal muscle: intermediate-to-dark signal

    • Normal tendons: low signal (dark)

    • Pathology: bright hyperintense areas along tendon or in surrounding soft tissue (indicative of inflammation, edema, or entrapment)

  • Proton Density Fat-Saturated (PD FS):

    • Normal muscle: intermediate-to-dark homogeneous signal

    • Normal tendons: dark, sharply defined fibers

    • Pathology: bright hyperintensity in tendons or myofascial planes from strain or microtears

    • Excellent for detecting subtle intermetatarsal edema and small tendon injuries

  • T1 Fat-Sat Post-Contrast:

    • Normal tendon: minimal or no enhancement

    • Inflamed tendons or peritendinous tissues: smooth linear or peritendinous enhancement

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

CT Appearance

Non-Contrast CT:

  • Tendons: appear as fine linear soft-tissue densities between metatarsal bones

  • Muscle bellies: soft-tissue density filling intermetatarsal spaces

  • Bony landmarks: clearly visible metatarsal shafts and phalangeal bases outlining tendon paths

  • Chronic pathology: subtle thickening or small calcifications at tendon insertions

Post-Contrast CT (standard):

  • Muscle bellies: homogeneous enhancement

  • Inflamed or thickened tendons: mild linear enhancement along intermetatarsal space

  • Useful in detecting chronic fibrosis, scarring, or entrapment syndromes in dorsal foot spaces

MRI images

Dorsal interossei tendons of foot sfov of the Foot axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

Dorsal interossei tendons of foot sfov of the Foot axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI images

Dorsal interossei tendons of foot sfov of the Foot axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002