Structures That Pass Through the Greater Sciatic Notch

The Greater Sciatic Notch is a passage from the pelvis into the buttock and thigh. The greater sciatic notch is the large, deep notch on the posterior part of the pelvis. The ischial spine separates the greater and lesser sciatic notches. The lesser sciatic notch is formed by the sacrotuberous ligament and the sacrospinous ligaments. The sacrospinous ligament separates the greater sciatic and lesser sciatic foramina.

The greater sciatic notch provides passage to many structures either above or below the piriformis muscle. The piriformis muscle originates from the sacrum and the greater sciatic notch and then inserts into the greater trochanter of the femur. There are structures that pass through the greater sciatic notch either above or below the piriformis muscle.

Structures passing above the piriformis muscle:

1. Superior Gluteal Artery
2. Superior Gluteal Nerve (L4-S1)

The superior gluteal artery could be injured from pelvic fractures or from harvesting of bone graft. Pelvic fractures may cause significant bleeding.

Arterial bleeding is sometimes difficult to control. When the bleeding is severe, the superior gluteal artery is responsible for the majority of the bleeding. Pelvic bleeding is usually venous or from the fracture itself. Harvesting of bone graft may also harm the superior gluteal artery. The superior gluteal nerve can be injured during Watson-Jones or lateral approaches if the incision extends more than 5cm above the acetabulum.

There are structures that pass from the greater sciatic notch below the piriformis muscle, and there is a mnemonic for it—POPS IQ (Pudendal Nerve, Nerve to the Obturator Internus, Posterior femoral cutaneous nerve, Sciatic Nerve, Inferior gluteal artery and nerve, Nerve to Quadratus Femoris).

1. Pudendal Nerve—below the piriformis
2. Nerve to Obturator Internus Muscle—nerves to superior gemellus and obturator internus
3. Posterior Cutaneous Nerve of the Thigh—below piriformis
4. Sciatic Nerve (below piriformis)—between the piriformis and superior gemellus muscles, the sciatic nerve is L4-S3.
5. Inferior Gluteal Artery & Nerve (below piriformis)—L5-S2
6. Nerve to Quadratus Femoris (below piriformis)—it gives branch to the quadratus femoris muscle and one to the inferior gemellus muscle.

There are three structures that pass from the greater sciatic notch into the lesser sciatic notch.

1. Nerve to obsturator Internus
2. Internal Pudendal Artery
3. Pudendal Nerve