Home › Body Atlas › Nerves › Nerve to Piriformis

Nerve to Piriformis

nervus musculi piriformis

The nerve to piriformis arises from the dorsal divisions of the S1 and S2 ventral rami of the sacral plexus. It enters the piriformis muscle on its anterior surface within the greater sciatic foramen, providing its sole motor innervation. The nerve is short and enters the muscle directly, reflecting the piriformis muscle's purely intrapelvic neuromuscular connection that is distinct from the sciatic nerve passing below it.

Region: Pelvis & Hip

Clinical Relevance

Clinical Notes

The nerve to piriformis is rarely considered clinically but is relevant in piriformis syndrome management: electromyographic confirmation of piriformis denervation indicates a specific injury to this nerve rather than a general sciatic or sacral plexus problem. In surgical approaches dividing the piriformis for access to the sciatic notch (some hip replacement approaches), awareness of the nerve entering the anterior surface helps preserve piriformis function. Selective motor nerve blocks of the piriformis can be used therapeutically in piriformis syndrome.

Pathology

Common Injuries & Conditions

Piriformis Denervation

Injury to the nerve to piriformis from sacral plexus trauma or direct muscular injury produces electromyographic evidence of denervation confined to the piriformis, helping localise the level of sacral plexus injury and distinguish piriformis syndrome from other hip external rotator pathology.