Topics

Topic

design image
Fibula

The fibula is the slender lateral bone of the leg, running parallel to the tibia. Though it does not bear significant weight, it plays an essential role in ankle stability, muscle attachment, and providing support for the lateral aspect of the leg. Its length extends from the knee to the ankle, with the proximal head articulating with the tibia and the distal end forming the lateral malleolus.

The fibula is clinically important in trauma, reconstructive surgery (as a donor graft), and in assessing marrow pathology on imaging.

Synonyms

  • Calf bone

  • Lateral leg bone

Muscular Attachments

  • Head of fibula: Biceps femoris (insertion), fibular collateral ligament, soleus

  • Shaft of fibula:

    • Anterior compartment: Extensor digitorum longus, extensor hallucis longus, peroneus tertius

    • Lateral compartment: Peroneus longus, peroneus brevis

    • Posterior compartment: Tibialis posterior, flexor hallucis longus, soleus

  • Distal fibula (lateral malleolus): Peroneus longus, peroneus brevis (grooves behind the malleolus), and ligaments of the ankle joint

Relations

  • Medial: Tibia, interosseous membrane, anterior tibial vessels, deep peroneal nerve

  • Lateral: Skin and superficial fascia of the lateral leg

  • Anterior: Extensor compartment muscles and anterior tibial artery

  • Posterior: Flexor hallucis longus, peroneal vessels, tibial nerve proximally

  • Distally: Articulates with talus at ankle (lateral malleolus), stabilizes ankle joint

Nerve Supply

  • No direct motor innervation (being bone), but periosteum and marrow are supplied by branches of the peroneal artery and nutrient vessels with accompanying sympathetic nerves for vascular tone and nociception

Arterial Supply

  • Nutrient artery from the peroneal artery

  • Periosteal branches from anterior tibial and peroneal arteries

Venous Drainage

  • Nutrient and periosteal veins drain into the peroneal vein and anterior tibial vein, ultimately into the popliteal vein

Function

  • Provides attachment for muscles of anterior, lateral, and posterior leg compartments

  • Forms the lateral malleolus, a key stabilizer of the ankle joint

  • Acts as a strut maintaining tibiofibular integrity

  • Serves as a donor bone for grafting in reconstructive surgery

MRI Appearance

T1-weighted images:

  • Bone marrow shows intermediate to bright signal intensity depending on fatty content

  • Cortical bone appears as very low signal (dark line)

T2-weighted images:

  • Bone marrow shows intermediate to bright signal intensity

  • Cortical bone remains dark

Proton Density (PD):

  • Marrow signal is intermediate to bright

  • Cortical margins remain low signal

STIR (Short Tau Inversion Recovery):

  • Marrow signal is normally low

  • Pathology (edema, tumor, infection) appears as bright hyperintensity

Proton Density Fat-Saturated (PD FS):

  • Marrow normally shows low signal due to fat suppression

  • Pathology stands out as bright hyperintense areas

T1 Fat-Sat Post-Contrast:

  • Normal marrow enhances mildly and diffusely

  • Pathological marrow (infection, tumor, fracture) enhances more heterogeneously or focally

CT Appearance

Non-Contrast CT:

  • Cortical bone: hyperdense (bright white)

  • Medullary cavity: lower density with visible trabecular pattern

  • Fractures: seen as cortical discontinuities, sclerosis in healing

Post-Contrast CT:

  • Cortical bone does not enhance

  • Marrow may enhance mildly if vascularized

  • Pathology (infection, tumor, inflammation) shows abnormal soft tissue or marrow enhancement

MRI image

fibula coronal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

fibula sag cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

CT image

fibula ct coronal image

CT image

fibula sag cti image

CT 3D VRT image

Fibula 3d