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Superior gluteal nerve

The superior gluteal nerve is a motor nerve arising from the sacral plexus. It originates from the posterior divisions of L4, L5, and S1 spinal nerves. It passes through the greater sciatic foramen above the piriformis muscle and divides into superior and inferior branches. It is the only nerve that exits the pelvis superior to the piriformis muscle.

The superior gluteal nerve innervates the gluteus medius, gluteus minimus, and tensor fasciae latae muscles, playing a crucial role in hip abduction and pelvic stabilization. Clinically, injury to this nerve leads to the characteristic Trendelenburg gait.

Synonyms

  • N. gluteus superior

  • Posterior branch of sacral plexus (L4–S1)

Origin, Course, and Branches

  • Origin: Posterior divisions of the ventral rami of L4, L5, and S1 nerves in the sacral plexus

  • Course:

    • Emerges from the sacral plexus in the pelvis

    • Exits the pelvis via the greater sciatic foramen above the piriformis muscle

    • Travels laterally between the gluteus medius and gluteus minimus muscles

    • Divides into superior and inferior branches

  • Branches:

    • Superior branch: Supplies the gluteus medius muscle

    • Inferior branch: Supplies gluteus medius, gluteus minimus, and tensor fasciae latae muscles

Relations

  • Anteriorly: Pelvic bones (ilium) and internal iliac vessels

  • Posteriorly: Gluteus medius muscle

  • Superiorly: Iliac crest and gluteal aponeurosis

  • Inferiorly: Piriformis muscle and superior gluteal vessels

Function

  • Motor innervation to gluteus medius, gluteus minimus, and tensor fasciae latae

  • Responsible for hip abduction and medial rotation of the thigh

  • Maintains pelvic stability during walking and single-leg stance

  • Essential for normal gait and posture

Clinical Significance

  • Injury (trauma, pelvic surgery, injection injury) causes weakness of hip abduction and positive Trendelenburg sign

  • Entrapment may occur at the greater sciatic foramen

  • Superior gluteal neuropathy may cause lateral hip pain, gait disturbance, and gluteal atrophy

  • Important to recognize in hip and pelvic imaging and sciatic foramen pathology

MRI Appearance

T1-weighted images:

  • Nerve appears as a thin low-to-intermediate signal intensity structure against bright fat planes

T2-weighted images:

  • Nerve demonstrates intermediate to mildly hyperintense signal compared to muscle

  • Abnormal nerve (edema, neuritis) appears brighter

STIR (Short Tau Inversion Recovery):

  • Normal nerve shows low signal

  • Pathology shows bright hyperintensity (entrapment, inflammation)

T1 Fat-Sat Post-Contrast:

  • Normal nerve shows minimal or no enhancement

  • Pathologic nerve enhances focally or diffusely (neuritis, tumor infiltration)

3D T2 SPACE / CISS:

  • Nerve shows intermediate to mildly hyperintense signal compared to muscle

  • Surrounded by bright fat/CSF, which provides excellent contrast

  • Allows precise delineation of its course between gluteus medius and minimus

CT Appearance

Non-Contrast CT:

  • Nerve is not directly visualized; inferred by location near superior gluteal vessels between gluteal muscles

  • Fat planes outline the region where the nerve runs

Post-Contrast CT:

  • Nerve does not enhance significantly

  • Pathology (tumors, inflammatory infiltration) may appear as enhancing soft tissue masses or stranding along the nerve course

MRI image