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Anterior division of obturator nerve (Anterior branch of obturator nerve)

The anterior division of the obturator nerve is a terminal branch of the obturator nerve (L2–L4), arising after the nerve passes through the obturator canal. It primarily supplies motor innervation to medial thigh adductor muscles and provides cutaneous innervation to the medial aspect of the thigh. It is clinically significant in nerve entrapments, pelvic surgeries, and evaluation of thigh and groin pain.

Synonyms

  • Obturator nerve (anterior branch)

  • Superficial branch of obturator nerve

  • Anterior obturator division

Origin, Course, and Termination

  • Origin:

    • Arises from the obturator nerve after it passes through the obturator canal in the pelvis

  • Course:

    • Descends in the medial thigh

    • Lies anterior to the adductor brevis muscle

    • Runs between the adductor longus (anteriorly) and adductor brevis (posteriorly)

    • Gives off motor and sensory branches along its path

  • Termination:

    • Ends by joining with the cutaneous branch to supply the medial thigh skin

Relations

  • Anteriorly: Adductor longus muscle

  • Posteriorly: Adductor brevis muscle

  • Medially: Gracilis muscle

  • Laterally: Femoral vessels in the upper thigh

Branches

  • Muscular branches: Supply adductor longus, adductor brevis, and gracilis

  • Cutaneous branch: Provides sensation to the skin on the medial aspect of the thigh

  • Articular branch: Contributes to hip joint innervation

Function

  • Motor: Innervates adductor longus, adductor brevis, and gracilis (aiding thigh adduction)

  • Sensory: Supplies sensation to the medial thigh skin via cutaneous branch

  • Articular: Contributes to sensory innervation of the hip joint capsule

Clinical Significance

  • Injury can cause weakness of thigh adduction and sensory loss on medial thigh

  • Involved in obturator neuropathy, which may occur due to pelvic trauma, surgery, or compression (e.g., hernia, pelvic tumors)

  • Important in nerve blocks for analgesia during hip or thigh surgeries

  • Must be considered in pelvic lymph node dissection and gynecological procedures

MRI Appearance

T1-weighted images:

  • Appears as a thin, linear, low-to-intermediate signal structure between adductor muscles

  • Surrounded by high-signal fat, which enhances its visibility

T2-weighted images:

  • Nerve demonstrates low signal intensity

  • Pathology (edema, neuritis, compression) appears as localized high signal intensity

STIR (Short Tau Inversion Recovery):

  • Normal nerve remains dark

  • Inflamed or compressed nerve becomes bright

T1 Fat-Sat Post-Contrast:

  • Normal nerve shows no significant enhancement

  • Pathology may show focal or diffuse enhancement (neuritis, tumor infiltration)

CT Appearance

Non-Contrast CT:

  • Nerve is not clearly visualized, but its course can be inferred by fat planes between adductor muscles

  • Enlarged or mass-affected nerves may appear as soft tissue thickening in expected location

Post-Contrast CT:

  • Normal nerve does not enhance significantly

  • Pathologic processes (tumor, infection, inflammation) may appear as enhancing soft tissue along its course

MRI image

Anterior division of obturator nerve MRI axial anatomy image-img-00000-00000

MRI image

Anterior division of obturator nerve MRI axial anatomy image-img-00000-00000_00001

MRI image

Anterior division of obturator nerve MRI axial anatomy image-img-00000-00000_00002

MRI image

Anterior division of obturator nerve MRI axial anatomy image-img-00000-00000_00003