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Lateral sural cutaneous nerve

The lateral sural cutaneous nerve is a sensory branch of the common fibular (peroneal) nerve in the popliteal fossa. It provides cutaneous innervation to the skin of the posterolateral aspect of the proximal leg. It is also clinically important because it often gives rise to the communicating peroneal nerve, which joins with the medial sural cutaneous nerve to form the sural nerve.

This nerve is relevant in peripheral nerve imaging, nerve conduction studies, and as a landmark in nerve graft harvesting or entrapment syndromes.

Synonyms

  • Lateral cutaneous nerve of the calf

  • Lateral sural branch of the common fibular nerve

  • External sural cutaneous nerve

Origin, Course, Branches, and Sensory Distribution

  • Origin:

    • Arises from the common fibular (peroneal) nerve in the popliteal fossa, usually near the lateral head of the gastrocnemius

  • Course:

    • Runs distally and laterally across the popliteal fossa

    • Travels over the lateral head of the gastrocnemius muscle

    • Descends along the posterolateral aspect of the leg in the superficial fascia

  • Branches:

    • Communicating peroneal branch (peroneal anastomotic branch):

      • Joins the medial sural cutaneous nerve from the tibial nerve to form the sural nerve

    • Cutaneous branches:

      • Supply skin of the lateral and posterior aspect of the upper calf

  • Sensory Distribution (“Insertion”):

    • Skin over the lateral upper one-third of the posterior leg

    • Contributes to sural nerve distribution over the lower posterior-lateral calf and foot when communication is present

Relations

  • Anteriorly: Lateral head of gastrocnemius muscle

  • Posteriorly: Popliteal fascia and skin of the popliteal fossa

  • Laterally: Fibular head and common fibular nerve

  • Medially: Popliteal vessels and tibial nerve (proximal relation)

Function

  • Provides pure sensory innervation to the posterolateral upper leg

  • Contributes to the sural nerve via the communicating branch, extending sensory coverage to the lower leg and lateral foot

Clinical Significance

  • Can be a donor in sural nerve graft harvesting

  • Entrapment or trauma may cause localized sensory deficits along lateral calf

  • May be affected in common fibular nerve injuries

  • Variations in communicating branches influence the formation of the sural nerve (important in nerve conduction studies and surgeries)

MRI Appearance

T1-weighted images:

  • Nerve appears as a thin linear low-to-intermediate signal structure surrounded by bright fat in the popliteal fossa and leg

T2-weighted images:

  • Nerve shows intermediate to mildly hyperintense signal compared to muscle

  • Pathology (edema, trauma, neuritis) appears brighter

STIR (Short Tau Inversion Recovery):

  • Normal nerve: low signal

  • Inflamed or injured nerve: bright hyperintensity

Proton Density Fat-Saturated (PD FS):

  • Normal nerve: low-to-intermediate signal

  • Pathology (neuropathy, injury): bright focal or diffuse signal

T1 Fat-Sat Post-Contrast:

  • Normal nerve: minimal enhancement

  • Pathological nerve: focal or diffuse enhancement in neuritis, trauma, or tumor infiltration

3D T2 SPACE / CISS:

  • Nerve shows intermediate to mildly hyperintense signal compared to muscle

  • Surrounded by bright fat/CSF, providing excellent contrast for nerve tracing

  • Useful in detecting small lesions or entrapment

CT Appearance

Non-Contrast CT:

  • Nerve not directly visualized

  • Appears as a soft tissue strand within surrounding fat at the posterolateral calf and popliteal fossa

  • Localized fat stranding may suggest injury or inflammation

Post-Contrast CT:

  • Nerve itself does not enhance

  • Pathology (nerve sheath tumors, inflammatory infiltration) may appear as enhancing soft tissue along its course

  • Associated muscle edema or fat stranding may highlight indirect pathology

MRI image

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

MRI image

Lateral sural cutaneous nerve mri scan

MRI image

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

MRI image

Lateral sural cutaneous nerve

CT image

Lateral Sural Cutaneous Nerve ct axial image