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Dorsal interossei tendon hand

The dorsal interossei tendons are the terminal tendinous expansions of the dorsal interosseous muscles, intrinsic muscles located between the metacarpal bones. These tendons insert onto the proximal phalanges and extensor expansions of the index, middle, and ring fingers.

The dorsal interossei abduct the fingers away from the midline of the hand and contribute significantly to metacarpophalangeal (MCP) joint flexion and interphalangeal (IP) joint extension, working in synergy with lumbricals and the extensor mechanism. Their tendons are essential for fine motor control and precision movements of the digits.

Synonyms

  • Dorsal interosseous tendon

  • Tendon of dorsal interossei muscle

  • Interosseous extensor contribution

Origin, Course, and Insertion

Origin (muscular):

  • Adjacent sides of two neighboring metacarpal shafts (except thumb and little finger)

Course:

  • Tendinous fibers extend distally on the dorsolateral aspect of the metacarpals

  • Join the extensor hood and pass to the proximal phalanx base

Insertion:

  • Proximal phalanx: Base of proximal phalanx on radial or ulnar side depending on finger

  • Extensor expansion (dorsal digital hood): Contributes to lateral bands assisting finger extension

Relations

  • Dorsally: Extensor tendons and dorsal aponeurosis

  • Palmarly: Palmar interossei, deep transverse metacarpal ligament

  • Laterally: Neurovascular bundles along each finger

  • Proximally: Metacarpal shafts and intermetacarpal fascia

  • Distally: Proximal phalanx and extensor expansion system

Function

  • Finger abduction: Move fingers away from midline (3rd digit axis)

  • MCP joint flexion: Assist lumbricals in flexing MCP joints

  • IP joint extension: Via contribution to extensor mechanism

  • Precision motion: Stabilize digits during grip, writing, and fine manipulation

  • Dynamic balance: Maintain finger alignment during power and precision tasks

MRI Appearance

T1-weighted images:

  • Tendons appear as dark, low-signal linear structures

  • Muscle bellies show intermediate signal

  • Fat between intermetacarpal spaces appears bright, highlighting tendon contours

  • MCP joint capsule and extensor hoods show low-signal fibrous structure

T2-weighted images:

  • Tendons: Low signal (dark)

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

  • Joint fluid: bright, outlining extensor hood contributions

  • Clear delineation between tendon, muscle belly, and adjacent soft tissue

STIR:

  • Tendons: dark to intermediate due to dense collagen

  • Muscle: intermediate-to-dark

  • Fat is fully suppressed, improving contrast around intermetacarpal spaces

  • Normal appearance is uniform without hyperintense signal

CT Appearance

Non-Contrast CT:

  • Tendons appear as soft-tissue density linear bands crossing MCP region

  • Muscle shows slightly higher density than surrounding fat

  • Bony anatomy (metacarpals, proximal phalanges) sharply defined

  • Extensor hood visible as thin soft-tissue band over proximal phalanx

MRI images

dorsal interossei tendon hand MRI axial image-img-00000-00000

MRI images

dorsal interossei tendon hand MRI axial image-img-00000-00000_00001