Anatomy of pelvic arteries adjacent to the sacrospinous ligament: importance of the coccygeal branch of the inferior gluteal artery

OBJECTIVE: To describe the arterial vascular anatomy in the area of the sacrospinous ligament. METHODS: Cadaver pelvises were dissected to reveal the anatomy of the sacrospinous ligament with emphasis on vascular and neuroanatomy. Flexible rulers were used to measure the coccygeal branch in five hemipelvises. RESULTS: The pudendal vessels and nerve pass immediately medial and inferior to the ischial spine (within 0.5 cm of the spine) and behind the sacrospinous ligament. The pudendal artery lies anterior to the sacrotuberous ligament, which passes behind the ischial spine to its attachment at the posterior ischial tuberosity. The inferior gluteal artery originates from the posterior or the anterior branch of the internal iliac artery to pass behind the sciatic nerve and the sacrospinous ligament. There is a 3- to 5-mm window in which the inferior gluteal vessel is left uncovered above the top of the sacrospinous ligament and below the lower edge of the main body of the sciatic nerve plexus. The coccygeal branch of the inferior gluteal artery passes immediately behind the midportion of the sacrospinous ligament and pierces the sacrotuberous ligament in multiple sites. The main body of the inferior gluteal artery leaves the pelvis by passing posterior to the upper edge of the sacrospinous ligament and following the inferior portion of the sciatic nerve out of the greater sciatic foramen. CONCLUSION: Sutures placed through the sacrospinous ligament at least 2.5 cm from the ischial spine along the superior border of the sacrospinous ligament and without transgressing the entire thickness are in an area generally free of arterial vessels.