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Lateral calcaneal branches of sural nerve

The lateral calcaneal branches of the sural nerve are small cutaneous branches arising from the sural nerve in the distal leg or around the ankle region. They supply sensory innervation to the skin over the lateral aspect of the heel and the proximal lateral foot.

These branches are variable in number and size and may arise either directly from the sural nerve or from its terminal continuation, the lateral dorsal cutaneous nerve. They play an important role in cutaneous sensation of the heel, and their injury or entrapment can lead to lateral heel pain, paresthesia, or numbness—especially after ankle surgery, trauma, or tight footwear compression.

Synonyms

  • Lateral calcaneal nerves

  • Heel branches of the sural nerve

  • Cutaneous branches of the sural nerve to the heel

Origin, Course, and Insertion

  • Origin: Emerge from the sural nerve as it descends along the posterior aspect of the lateral ankle or the lower one-third of the leg.

  • Course: Small branches curve anteriorly and inferiorly around the posterolateral aspect of the calcaneus, coursing superficial to the Achilles tendon and deep to the skin and subcutaneous tissue.

  • Termination: Supply the lateral and posterolateral skin of the heel and occasionally the proximal lateral surface of the foot.

Relations

  • Superiorly: Sural nerve and small saphenous vein

  • Inferiorly: Lateral aspect of calcaneus and skin of heel

  • Anteriorly: Lateral dorsal cutaneous nerve and peroneal tendons

  • Posteriorly: Achilles tendon and its paratenon

  • Laterally: Subcutaneous fat and skin

  • Medially: Plantar branches of the tibial nerve (distinct territory division at heel midline)

Function

  • Sensory innervation: Provides cutaneous sensation to the lateral aspect of the heel and proximal lateral foot.

  • Protective feedback: Carries sensory input for pressure and pain over the heel during standing and walking.

  • Clinical relevance: Serves as an anatomical landmark in sural nerve conduction studies and nerve graft harvesting.

Clinical Significance

  • Neuropathy: Entrapment or injury may cause numbness, burning, or tingling over the lateral heel.

  • Trauma and surgery: Frequently affected during Achilles tendon repair, calcaneal fracture fixation, or ankle incision.

  • Iatrogenic injury: May result from ankle arthroscopy portals or lateral calcaneal osteotomies.

  • Sural nerve harvest: Injury to these branches can cause localized heel anesthesia post-surgery.

  • Imaging relevance: MRI and high-resolution ultrasound are useful for detecting neuromas, entrapment, or postoperative scarring.

MRI Appearance

  • T1-weighted images:

    • Normal branches: low to intermediate signal linear or thread-like structures within the subcutaneous fat.

    • Surrounding fat: bright signal, improving nerve visibility.

    • Entrapment or neuroma: focal thickening or intermediate-to-bright signal intensity.

  • T2-weighted images:

    • Normal nerve: slightly darker than on T1, with low-to-intermediate signal.

    • Pathologic nerve (neuritis or injury): hyperintense, swollen, or irregular appearance.

    • Post-traumatic or post-surgical fibrosis: may show mixed signal intensity adjacent to calcaneus or Achilles tendon.

  • STIR:

    • Normal: nerves appear as low signal threads in the subcutaneous tissue.

    • Pathology: bright hyperintense signal indicates inflammation, edema, or neuroma.

  • Proton Density Fat-Saturated (PD FS):

    • Normal: low-signal fine linear nerve within bright fat background.

    • Entrapment or inflammation: focal or diffuse hyperintensity along course of nerve.

    • Best sequence for detecting subtle neuritis and postsurgical scarring.

  • T1 Fat-Sat Post-Contrast:

    • Normal: minimal enhancement.

    • Pathology: nodular or diffuse enhancement seen in traumatic neuroma, neuritis, or perineural scar formation.

CT Appearance

Non-Contrast CT:

  • Lateral calcaneal branches not directly visible.

  • Indirect signs of injury: soft-tissue thickening, scarring, or fat stranding near the Achilles tendon or lateral heel.

  • Calcaneal fractures or osteotomies may cause entrapment of nearby nerve branches.

Post-Contrast CT (standard):

  • Nerves remain indistinct; however, perineural enhancement or adjacent soft-tissue changes may suggest neuritis or postoperative fibrosis.

  • Useful in conjunction with MRI for surgical planning or trauma assessment.

MRI images

Lateral calcaneal branches of sural nerve axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

Lateral calcaneal branches of sural nerve axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI images

Lateral calcaneal branches of sural nerve axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002