Ligaments and foramina of gluteal region

Ligaments of gluteal region:

The two important ligaments of the gluteal region are sacrotuberour and sacrospinous ligaments. These ligaments stabilize the sacrum and prevent its rotation at the sacroiliac joint by the weight of vertebral column.

Sacrotuberous ligament: It connects the back of the sacrum to the ischial tuberosity. It is attached to lower part of the sacrum and ischial tuberosity and converts the lesser sciatic notch of hip bone into lesser sciatic foramen.

Sacrospinous ligament: It connects the back of sacrum to the spine of ischium. It is attached to the lower part of sacrum and ischial spine and converts the greater sciatic notch of the hip bone into greater sciatic foramen.

Foramina of gluteal region:

There are two important foramina in the gluteal region: greater sciatic foramen and lesser sciatic foramen.
Greater sciatic foramen:

It is formed by the greater sciatic notch of hip bone and sacrospinous ligament. Sacrotuberous ligament also plays some role in formation of this foramen. The greater sciatic foramen provides an exit from the pelvis into the gluteal region and structures that come from pelvis into the leg pass through this foramen.

The following structures pass through this foramen.

  • Prirformis muscle
  • Sciatic nerve
  • Posterior Cutaneous nerve of thigh
  • Superior and inferior gluteal nerves
  • Nerves to obturator internus muscle and quadratus femoris muscle
  • Pudendal nerve
  • Superior and inferior gluteal arteries
  • Internal pudendal artery and vein

Lesser sciatic foramen:

It is formed by the lesser sciatic notch of hip bone and the sacrotuberous ligament. Sacrospinous ligament also plays some role in formation of this foramen. In contrast to the greater sciatic foramen, it provides and entrance into the pelvis from the gluteal region, so the structures that go to the pelvis from gluteal region pass through it. In this way, its presence enables blood vessels and nerves that have left the pelvis through the greater sciatic foramen above the pelvic floor to reenter the perineum below the pelvic floor.

The following structures pass through it.

  • Tendon of obturator internus muscle
  • Nerve to obturator internus
  • Pudendal nerve
  • Internal pudendal artery and vein