n :  either of two notches on the dorsal border of the hipbone on each side that when closed off by ligaments form the corresponding sciatic foramina:  a  :  a relatively large notch just above the ischial spine that is converted into the greater sciatic foramen by the sacrospinous ligament - called also greater sciatic notch   b  :  a smaller notch just below the ischial spine that is converted to the lesser sciatic foramen by the sacrospinous ligament and the sacrotuberous ligament - called also lesser sciatic notch  .
 
 
 
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