Greater sciatic foramen

The greater sciatic foramen is a critical anatomical passage in the pelvis that allows for the transition of several vital structures between the pelvic cavity and the gluteal region.^[1]

Location

Located in the posterior pelvis, the greater sciatic foramen is bordered by several bony landmarks and ligaments:

• Above and in front by the posterior margin of the hip bone.
• Behind by the sacrotuberous ligament.
• Below by the sacrospinous ligament.^[8]
• And, finally, it has a bony floor made up of the sacrum and the coccyx.

Structure

Shape: It is a roughly triangular opening, larger at the top and tapering down. Borders: The foramen's superior border is the greater sciatic notch of the ilium, the inferior border is framed by the sacrotuberous and sacrospinous ligaments, and posteriorly, it is bordered by the sacrum.

Function

Neurovascular Passage: The primary function of the greater sciatic foramen is to act as a passageway for numerous neurovascular structures.^[6] This includes the large sciatic nerve, the posterior cutaneous nerve of the thigh, and the pudendal nerve, among others. Muscular and Tendinous Passage: Several muscles and tendons also navigate through this foramen, such as the piriformis muscle, which exits the pelvis to enter the gluteal region. Vascular Structures: It allows for the passage of the superior and inferior gluteal arteries, veins, and nerves.^[3]

Clinical Significance

The greater sciatic foramen holds immense clinical relevance due to the essential structures it accommodates.^[4] Notably, the sciatic nerve, the largest nerve in the body, passes through this foramen, and its entrapment or irritation can lead to sciatica—a condition characterized by pain, tingling, or numbness radiating down the leg. The foramen's relation to the piriformis muscle is also significant; if the muscle becomes hypertrophic or spasmodic, it can compress the sciatic nerve, resulting in piriformis syndrome.^[2] Furthermore, the superior and inferior gluteal arteries, which supply blood to parts of the pelvis and gluteal region, traverse the foramen, making it a vital area to be aware of during surgeries to avoid inadvertent injury.^[5] Additionally, when accessing the gluteal region in procedures, like gluteal injections or hip surgeries, knowledge of the greater sciatic foramen's anatomy ensures avoidance of nerve or vascular damage.