Corpus: Greater ischiadic foramen

The greater sciatic foramen is a passageway for important pathways in the pelvic region that is limited by bone and ligament structures.

The greater sciatic foramen is bordered by the following structures:

• cranially: by the sacroiliac joint and the sacroiliac anterior ligament
• lateral: from the greater sciatic notch
• medial: from the sacrotuberous ligament
• caudal: from the sacrospinous ligament and from the ischial spine

The piriformis muscle runs through the large ischial hole and divides it into an upper, suprapiriform and a lower, infrapiriform part. Several vessels and nerves run through these gaps.

Foramen suprapiriforme[Bearbeiten]

• Superior gluteal artery: The superior gluteal artery, which arises from the internal iliac artery, supplies the gluteus medius, gluteus minimus and gluteus maximus muscles.
• Superior gluteal vein: its catchment area includes the gluteus maximus muscle, the gluteus medius muscle and the gluteus minimus muscle. The superior gluteal vein flows into the internal iliac vein.
• Superior gluteal nerve: The superior gluteal nerve, which originates from the sacral plexus, innervates the gluteus medius muscle, the gluteus minimus muscle and the tensor fasciae latae muscle.

Foramen infrapiriforme[Bearbeiten]

• Inferior gluteal artery: The gluteus maximus muscle and the dorsal part of the thigh belong to the supply area of the inferior gluteal artery coming from the internal iliac artery.
• Inferior gluteal vein: Its catchment area includes the gluteus maximus muscle and the dorsal part of the thigh. It flows into the internal iliac vein.
  
• Inferior gluteal nerve: The inferior gluteal nerve originates from the sacral plexus and innervates the gluteus maximus muscle.
• Ischiadicus nerve: The ischiadicus nerve supplies the ischiocrural muscles and all muscles caudal to the knee joint. Its sensory supply area includes the skin caudal to the knee joint (with the exception of the medial side).
• Posterior femoral cutaneous nerve: The posterior femoral cutaneous nerve, which is part of the sacral plexus, supplies the dorsal side of the thigh with sensory information.
• Nervus musculi quadrati femoris: It supplies the quadratus femoris muscle.
• Internal pudendal artery: The internal pudendal artery originates from the internal iliac artery and runs to the urogenital region. It supplies the rectum and structures in the urogenital region.
• Internal pudendal vein: The catchment area of the internal pudendal vein includes the urogenital region. It flows into the internal iliac vein.
• Pudendal nerve: The pudendal nerve supplies the sphincter ani externus muscle, the muscles in the urogenital region and the skin on the dorsal side of the external genitalia.
• Internal obturator nerve: Supplies the internal obturator muscle.

The latter 4 structures first run through the infrapiriform foramen, then pass around the ischial spina and enter the lesser ischial foramen.

See also: Piriformis syndrome, Foramen ischiadicum minus