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Lateral dorsal cutaneous nerve

The lateral dorsal cutaneous nerve is the terminal continuation of the sural nerve as it crosses the lateral aspect of the ankle to reach the dorsum of the foot. It provides sensory innervation to the lateral dorsum of the foot and the fifth toe, contributing to the cutaneous nerve network of the ankle and foot.

This small but clinically important nerve is vulnerable to trauma, compression, or surgical injury around the lateral malleolus, particularly in fractures, surgical incisions, and tight footwear. Injury can cause numbness, tingling, or burning pain along the lateral foot border.

Synonyms

  • Lateral terminal branch of the sural nerve

  • Lateral dorsal nerve of the foot

  • Lateral dorsal sensory branch of the sural nerve

Origin, Course, and Insertion

  • Origin: Arises as the terminal continuation of the sural nerve at the level of the lateral malleolus.

  • Course: Curves anteriorly below and in front of the lateral malleolus, passing beneath the fibular retinaculum, then runs along the lateral margin of the foot.

  • Termination: Ends as fine cutaneous branches over the lateral aspect of the fifth toe and adjoining dorsolateral skin of the foot.

Relations

  • Superiorly: Lateral malleolus and fibular retinaculum

  • Inferiorly: Lateral border of the foot

  • Anteriorly: Extensor digitorum brevis and lateral tarsal structures

  • Posteriorly: Continuation of the sural nerve behind the lateral malleolus

  • Medially: Dorsal venous arch and small veins of the foot

  • Laterally: Skin and superficial fascia of the lateral dorsum

Function

  • Sensory innervation: Provides cutaneous sensation to the lateral dorsal aspect of the foot and the lateral side of the fifth toe

  • Protective role: Conveys pain, touch, and temperature sensations

  • Clinical significance: Helps differentiate sural neuropathy from peroneal or tibial nerve lesions in sensory mapping

Clinical Significance

  • Entrapment: Compression beneath the fibular retinaculum or in scar tissue after lateral ankle surgery

  • Trauma: Direct laceration or traction injury during lateral malleolar fractures or surgical fixation

  • Sural neuropathy: May extend to affect its terminal branch, causing sensory loss on the lateral dorsum

  • Symptoms: Burning, tingling, numbness, or pain radiating along the lateral border of the foot

  • Iatrogenic injury: Possible during ankle arthroscopy, Achilles tendon surgery, or lateral malleolar approaches

MRI Appearance

  • T1-weighted images:

    • Normal nerve: thin, linear, low-to-intermediate signal structure along the lateral ankle

    • Surrounded by bright subcutaneous fat

    • In neuropathy: nerve may appear thickened or hyperintense due to edema or fibrosis

  • T2-weighted images:

    • Normal: intermediate signal, slightly brighter than muscle but darker than fat

    • Pathology: focal or diffuse hyperintense signal indicates neuritis or entrapment

    • Chronic fibrosis may appear as thickened low-signal band

  • STIR (Short Tau Inversion Recovery):

    • Normal: low signal (dark)

    • Pathologic nerve: bright hyperintense, indicating edema or inflammatory changes

    • Useful in detecting subtle entrapment around the lateral malleolus

  • Proton Density Fat-Saturated (PD FS):

    • Normal: linear, dark structure along lateral ankle and foot border

    • Neuropathy or inflammation: bright hyperintense signal with perineural edema

    • Surrounding fat suppression enhances contrast between normal and abnormal nerve

  • T1 Fat-Sat Post-Contrast:

    • Normal: minimal or no enhancement

    • Pathologic: enhancement of the nerve or perineural tissue seen in neuritis, entrapment, or scarring

    • Postoperative changes: irregular enhancement around scar tissue

CT Appearance

Non-Contrast CT:

  • Nerve not directly visualized (small soft-tissue structure)

  • Indirect clues: Perineural fat plane distortion, surgical scar, or adjacent bony abnormality

  • May show soft tissue thickening or edema near the lateral malleolus

Post-Contrast CT (standard):

  • Normal nerve: not significantly enhanced

  • Pathologic nerve: enhancing soft tissue around its course, indicating inflammation or fibrosis

  • May reveal entrapment by callus, implant, or fibrotic tissue

MRI images

Lateral dorsal cutaneous nerve axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

Lateral dorsal cutaneous nerve axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI images

Lateral dorsal cutaneous nerve axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002

MRI images

Lateral dorsal cutaneous nerve coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

Lateral dorsal cutaneous nerve sagl cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000