The sacrotuberous and sacrospinous ligaments close the greater and lesser sciatic notches, respectively, forming foramen from which structures enter or leave the pelvis and perineum. These two ligaments resist backward rotation of the inferior end of the sacrum and provide an origin for the gluteus maximus muscle.
• Greater Sciatic Foramen – doorway for structures entering or leaving the pelvis (e.g. sciatic nerve).
• Lesser Sciatic Foramen – doorway for structures entering or leaving the perineum (e.g. pudendal nerve).
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