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Metatarsal interosseous ligaments

The metatarsal interosseous ligaments are strong fibrous bands connecting the bases of the second to fifth metatarsal bones on their adjacent sides. They form a key component of the intermetatarsal joint complex, providing stability and preventing excessive separation of the metatarsal bases during weight-bearing and locomotion.

These ligaments are important static stabilizers of the transverse arch of the foot, working in coordination with the deep transverse metatarsal ligament, interossei muscles, and plantar fascia. They also play a crucial role in maintaining the metatarsal alignment and load distribution during walking and running.

Synonyms

  • Intermetatarsal interosseous ligaments

  • Dorsal interosseous metatarsal ligaments

  • Ligamenta interossea metatarsalia

Attachments (Origin and Insertion)

  • Origin: Lateral aspect of the base of the medial metatarsal (second to fourth)

  • Insertion: Medial aspect of the base of the adjacent lateral metatarsal (third to fifth)

  • These ligaments are absent between the first and second metatarsals, allowing greater mobility at the first tarsometatarsal joint.

Course

  • Each ligament runs transversely between adjacent metatarsal bases, deep to the dorsal ligaments and superficial to the plantar ligaments.

  • They are short and robust, oriented slightly obliquely from dorsal to plantar, helping stabilize the transverse metatarsal arch.

  • Together, they form a fibrous intermetatarsal tunnel, through which interosseous muscles, vessels, and nerves pass.

Relations

  • Dorsally: Dorsal intermetatarsal ligaments and dorsal interosseous muscles

  • Ventrally (Plantar side): Deep transverse metatarsal ligament and plantar interossei

  • Laterally: Intermetatarsal bursae

  • Medially: Intermetatarsal spaces containing neurovascular bundles

Nerve Supply

  • Deep branch of the lateral plantar nerve

  • Interosseous branches of the deep fibular (peroneal) nerve

Function

  • Stabilization: Maintains alignment between adjacent metatarsal bones

  • Arch support: Reinforces the transverse metatarsal arch

  • Load distribution: Aids in even weight transfer across the forefoot

  • Restriction of movement: Limits excessive spreading of metatarsal bases

  • Assists foot rigidity: Provides static support during push-off phase of gait

Clinical Significance

  • Sprains or tears: May result from forced abduction or torsion injuries of the forefoot

  • Intermetatarsal bursitis: Inflammation between ligaments may mimic Morton’s neuroma symptoms

  • Degenerative changes: Seen in chronic overuse or biomechanical imbalance (e.g., flatfoot deformity)

  • Surgical importance: Key structure preserved or repaired during corrective forefoot procedures

  • Imaging relevance: MRI is essential for evaluating ligament integrity in forefoot trauma or metatarsalgia

MRI Appearance

  • T1-weighted images:

    • Ligaments appear as thin low-signal (dark) bands between adjacent metatarsal bases.

    • Surrounding muscle and fat show intermediate to high signal, highlighting ligament contrast.

    • Tears or sprains present as discontinuity or intermediate signal thickening.

  • T2-weighted images:

    • Normal ligament remains low signal and well defined.

    • Acute injury shows focal bright hyperintense signal within or around the ligament due to edema.

    • Chronic degeneration may appear as thickened, irregular low-to-intermediate signal bands.

  • STIR:

    • Normal ligament is dark.

    • Edema, bursitis, or inflammation shows bright hyperintense signal between metatarsal bases.

  • Proton Density Fat-Saturated (PD FS):

    • Ligament appears as a thin, dark linear structure.

    • Partial tear: bright signal line traversing ligament fibers.

    • Complete tear: discontinuity with fluid-filled hyperintense gap.

    • Excellent for detecting subtle sprains and soft-tissue edema.

  • T1 Fat-Sat Post-Contrast:

    • Normal ligament shows minimal or no enhancement.

    • Inflamed or healing ligament exhibits periligamentous enhancement.

    • Chronic scarring: irregular enhancement due to fibrotic tissue.

CT Appearance

Non-Contrast CT:

  • Ligaments not well visualized directly (soft-tissue density).

  • Indirect findings include joint space asymmetry, periarticular calcification, or metatarsal base malalignment.

  • Chronic traction may cause subtle cortical irregularity or sclerosis at ligament attachment sites.

Post-Contrast CT (standard):

  • Ligaments show mild uniform enhancement due to vascularized connective tissue.

  • Adjacent bursitis or synovitis may appear as enhancing soft-tissue thickening between metatarsal bases.

  • CT helps detect associated osseous injury, small avulsion fragments, or degenerative changes.

MRI images

Metatarsal interosseous ligaments coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

Metatarsal interosseous ligaments coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI images

Metatarsal interosseous ligaments coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002

MRI images

Metatarsal interosseous ligaments coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00003