Inferior Gluteal NerveEdit

The inferior gluteal nerve is a major motor nerve of the gluteal region. It arises from the sacral plexus and provides the primary neural input to the gluteus maximus, the large muscle that powerfully extends and externally rotates the hip and helps stabilize the pelvis during locomotion. The nerve typically carries fibers from nerve roots L5 to S2 and travels with accompanying vessels as it leaves the pelvis to enter the gluteal region. It is commonly described as a branch of the sacral plexus that travels through the greater sciatic foramen.

Anatomy and course - Origin and roots: The inferior gluteal nerve originates from the anterior divisions of the ventral rami of the sacral nerves, usually carrying fibers from L5 to S2. It may receive variable contribution from adjacent roots, as seen in some individuals. - Exit and path: The nerve exits the pelvis through the greater sciatic foramen inferior to the piriformis muscle, then dives deep to the gluteus maximus as it approaches its target. - Relations: It travels with the inferior gluteal vessels and lies in close association with the gluteus maximus muscle, supplying its deep surface and providing articular branches in some individuals. - Branches: The primary motor branches go to the gluteus maximus. In some cases, small articular branches to the hip joint or adjacent tissues may arise.

Structure and innervation - Target muscle: The sole and principal innervation provided by the inferior gluteal nerve is to the gluteus maximus, the strongest extensor of the hip. - Functional fibers: The nerve contains motor fibers that drive hip extension and external rotation, and may contribute to stabilization of the pelvis during weight-bearing activities.

Function - Primary actions: By innervating the gluteus maximus, the inferior gluteal nerve enables powerful hip extension (for example, standing from a seated position, climbing stairs, rising from a chair, and running). It also assists in external rotation of the thigh and in maintaining hip and trunk stability during movement. - Clinical relevance: Weakness or injury to this nerve impairs activities requiring strong hip extension, such as rising from a chair or climbing and sprinting, and can contribute to gait abnormalities when the buttock power is compromised.

Clinical significance - Etiology of injury: The inferior gluteal nerve can be affected by trauma to the pelvis or hip, surgical procedures in the gluteal region, or compression. Iatrogenic injury can occur during intramuscular injections into the gluteal region if injections are placed too deeply or in an incorrect location. Pelvic fractures, dislocations, or prolonged lithotomy positioning can also put the nerve at risk. - Presentation: Individuals with injury to the inferior gluteal nerve may experience weakness of hip extension, difficulty with rising from a seated position, trouble climbing stairs or running, and a reduction in the power phase of gait. The exact pattern depends on the extent and location of the nerve involvement. - Diagnosis and testing: Clinicians use a combination of physical examination (strength testing of hip extension), nerve conduction studies, and electromyography (electromyography), along with imaging studies such as magnetic resonance imaging (magnetic resonance imaging), to assess nerve integrity and rule out other causes of hip weakness. - Management: Treatment ranges from conservative approaches—physical therapy to strengthen the gluteus maximus and improve functional gait, activity modification, and analgesia—to surgical or interventional approaches if there is persistent entrapment or inaccessible pathology. Recovery depends on the mechanism of injury and the extent of nerve damage.

Clinical considerations and variations - Variants: Like many peripheral nerves, the inferior gluteal nerve can show anatomical variation. In some individuals, branches to the gluteus maximus may originate from different points along the sacral plexus, or additional small neurological contributions to nearby musculature may be present. - Differential diagnosis: Weakness in hip extension can arise from injury to the inferior gluteal nerve, but other conditions—such as problems with the gluteus maximus muscle itself, adjacent nerves, or pineal or spinal nerve roots—must be distinguished through careful clinical and electrodiagnostic evaluation.

Imaging and diagnostics - Electrophysiology: Electromyography (electromyography) and nerve conduction studies help determine whether the inferior gluteal nerve is impaired and assess the extent of denervation in the gluteus maximus. - Imaging: Magnetic resonance imaging (magnetic resonance imaging) and, when indicated, ultrasound may visualize nerve pathways, identify compression, and assess associated soft-tissue pathology.

See also - gluteus maximus - sacral plexus - greater sciatic foramen - piriformis - hip joint - intramuscular injection - electromyography - magnetic resonance imaging