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Interosseous membrane of leg

The interosseous membrane of the leg is a strong fibrous sheet connecting the interosseous borders of the tibia and fibula, extending from just below the tibial tuberosity to the superior surface of the talus, where it continues into the inferior tibiofibular syndesmosis. It serves as a firm yet flexible partition separating the anterior and posterior compartments of the leg and provides attachment for several deep leg muscles.

The membrane also acts as a stabilizer for the tibia and fibula, maintaining their spacing during movement and weight-bearing. Openings in the membrane allow passage of vessels between compartments, particularly the anterior tibial vessels and deep peroneal nerve, which pierce the membrane superiorly.

Synonyms

  • Middle tibiofibular ligament

  • Crural interosseous membrane

  • Tibiofibular interosseous septum

Origin, Course, and Insertion

  • Origin: Arises from the interosseous border of the tibia, extending obliquely downward and laterally

  • Course: Fibers run predominantly downward from the tibia to the fibula; the upper part contains an oval aperture for passage of the anterior tibial vessels; a smaller inferior opening allows communication with the inferior tibiofibular syndesmosis

  • Insertion: Attaches along the interosseous crest of the fibula and continues inferiorly into the interosseous ligament at the distal tibiofibular joint

Relations

  • Anteriorly: Tibialis anterior, extensor hallucis longus, and extensor digitorum longus (muscles of the anterior compartment)

  • Posteriorly: Tibialis posterior and flexor hallucis longus muscles

  • Superiorly: Pierced by the anterior tibial vessels and deep fibular (peroneal) nerve

  • Inferiorly: Continues with the interosseous ligament of the distal tibiofibular syndesmosis

  • Laterally: Fibula

  • Medially: Tibia

Nerve Supply

  • Sensory twigs from the deep fibular (peroneal) nerve and tibial nerve

Function

  • Structural support: Binds the tibia and fibula together, maintaining the integrity of the leg’s bony framework

  • Compartmental separation: Divides the leg into anterior and posterior compartments

  • Muscle attachment: Provides surface area for deep flexors and extensors

  • Force transmission: Transfers axial and torsional loads between tibia and fibula during weight-bearing and locomotion

  • Neurovascular pathway: Allows passage of the anterior tibial artery and deep fibular nerve through its upper aperture

Clinical Significance

  • Syndesmotic injuries: High ankle sprains may disrupt the interosseous membrane, leading to tibiofibular instability

  • Compartment syndrome: Acts as a rigid boundary that may limit expansion during hemorrhage or swelling

  • Fracture association: Tibial and fibular shaft fractures may involve tearing of the membrane, affecting alignment

  • Surgical relevance: Must be preserved during fasciotomy and tibial fixation procedures

  • Imaging importance: MRI helps evaluate tears, inflammation, and interosseous edema in trauma and overuse injuries

MRI Appearance

  • T1-weighted images:

    • Normal membrane: low signal (dark linear structure) between tibia and fibula

    • Surrounding muscle: intermediate signal

    • In tears: disruption or focal hyperintense gap in the membrane

    • Fat around the membrane appears bright, outlining its course

  • T2-weighted images:

    • Normal: low signal, slightly darker than on T1

    • Pathology: bright hyperintense signal representing edema, hematoma, or partial rupture

    • Fluid-sensitive sequences highlight peri-membranous inflammation or hemorrhage

  • STIR:

    • Normal: uniformly dark linear band

    • Pathology: hyperintense changes consistent with edema, tearing, or syndesmotic sprain extension

  • Proton Density Fat-Saturated (PD FS):

    • Normal: dark, well-defined fibrous band between tibia and fibula

    • Tears or sprains: bright linear signal within or adjacent to the membrane

    • Best for identifying partial-thickness disruptions or interosseous edema

  • T1 Fat-Sat Post-Contrast:

    • Normal: minimal or no enhancement

    • Pathologic: enhancement along disrupted fibers or at tibiofibular attachment sites

    • Indicates inflammatory or post-traumatic change

CT Appearance

Non-Contrast CT:

  • The membrane itself is not distinctly visualized (thin soft tissue density between tibia and fibula)

  • Indirect findings: widening of interosseous space or tibiofibular diastasis suggestive of membrane injury

  • Associated fractures or ossification may be visible in chronic trauma

Post-Contrast CT (standard):

  • The membrane remains poorly defined without intra-articular contrast

  • Perimembranous soft tissue swelling or hematoma may be inferred

  • Chronic injury may demonstrate calcification or scarring along the membrane

MRI image

Interosseous membrane of leg axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Interosseous membrane of leg axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI image

Interosseous membrane of leg axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002

MRI image

Interosseous membrane of leg axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00003