[TA] a pointed process from the posterior border of the ischium on a level with the lower border of the acetabulum; gives attachment to the coccygeus muscle and sacrospinous ligament; the pudendal nerve passes dorsal to the ischial spine, which is palpable per vagina or rectum, and thus is used as a target for the needle tip in administering a pudendal nerve block. SYN: spina ischiadica [TA], ischiadic spine, sciatic spine.