Superior gluteal nerve
Nervus gluteus superior
A branch of the sacral plexus (L4–S1) that leaves the pelvis above piriformis to supply gluteus medius, gluteus minimus and tensor fasciae latae. These are the hip abductors that keep the pelvis level when walking, and their paralysis produces a positive Trendelenburg sign.
Overview
The superior gluteal nerve arises from the posterior divisions of L4, L5 and S1. It is the only nerve to leave the pelvis through the greater sciatic foramen above piriformis, together with the superior gluteal artery and vein. It then runs laterally between gluteus medius and gluteus minimus, supplying both, and ends in tensor fasciae latae.
These muscles are the main hip abductors and medial rotators. More importantly, in the stance phase of gait they hold the pelvis level by pulling the ilium of the stance side toward the femur, which stops the pelvis dropping on the side of the swinging leg. When the nerve or the muscles fail, the pelvis tilts down on the opposite (unsupported) side whenever the patient stands on the affected leg.
- Location
Greater sciatic foramen (suprapiriform) → between gluteus medius and minimus → tensor fasciae latae.
Anatomy
- Innervation
Gluteus medius, gluteus minimus and tensor fasciae latae (no cutaneous branches).
- Nerve roots
L4, L5, S1.
- Course
Sacral plexus → greater sciatic foramen above piriformis (with the superior gluteal vessels) → between gluteus medius and minimus → ends in tensor fasciae latae.
Function
- Abduction and medial rotation of the hip
- Stabilisation of the pelvis on the stance leg during walking (preventing contralateral pelvic drop)
Clinical significance
Trendelenburg sign and gait
When the patient stands on the affected leg, the pelvis drops on the opposite side (a positive Trendelenburg sign). When walking, they lurch the trunk toward the affected side to keep the centre of gravity over the stance hip ("waddling" or gluteal gait; bilateral palsy causes a waddle). Causes include hip arthroplasty through a lateral approach, pelvic fractures, poorly placed intramuscular injections and L5 radiculopathy. The sign is also positive with hip osteoarthritis, hip dysplasia and coxa vara.
Safe gluteal intramuscular injection
Give gluteal injections in the upper outer (superolateral) quadrant of the buttock, which is clear of the sciatic nerve in the lower medial area. Better still, use the ventrogluteal site (gluteus medius, in the triangle between the ASIS, the iliac tubercle and the greater trochanter). This also avoids the main trunk of the superior gluteal nerve and vessels, which emerge more medially at the upper border of piriformis.
Test yourself
When standing on the right leg, the patient's left side of the pelvis drops. Which nerve is injured?
- Left superior gluteal nerve
- Right superior gluteal nerve
- Right inferior gluteal nerve
- Right femoral nerve
Answer: Right superior gluteal nerve
A positive Trendelenburg sign means the hip abductors (gluteus medius and minimus) of the stance leg have failed. They are supplied by the superior gluteal nerve (L4–S1), so the lesion is on the right and the unsupported left side drops.
Compiled from standard anatomy and physiology references — see the Nervous System sources. For education only; not medical advice.