Ischium- ischial spine

Medial view (deep surface), right side

Medial view (deep surface), left side

Medial view (deep surface), right and left respectively

In addition to being important to the Boston Red Sox, gold fish, and butterflies (I think Al was losing it when we got to this lab) the ischial spine is the attachment for the sacrospinous ligament. The sacrospinous ligament is a triangular shaped ligament that is strong, attaching the coccyx and sacrum to the ischial spine. With the sacrotuberous ligament it forms the boundaries for the lesser sciatic foramen. Functionally it of great significance because with the sacrotuberous ligament it prevents the sacrum from rotating and breaking away from the os coxae. Because of the force from the lumbar vertebrae pushing inferiorly on the sacral promontory, it would rotate forward and inferiorly if it were not for these two ligaments.