| sacral plexus | Formed by the fourth and fifth lumbar (lumbosacral trunk) and first, second, and third sacral nerves; it lies on the inner surface of the posterior wall of the pelvis usually embedded in the piriformis muscle; its nerves supply the lower limbs, its major product being the sciatic nerve. Synonym: plexus sacralis, ischiadic plexus, sciatic plexus. (05 Mar 2000) |
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| sacral promontory | The most prominent anterior projection of the base of the sacrum. Synonym: pelvic promontory, promontorium ossis sacri, promontory of the sacrum. (05 Mar 2000) |
| sacral region | The area of the back overlying the sacrum. Synonym: regio sacralis. (05 Mar 2000) |
| sacral splanchnic nerves | Branches from the sacral sympathetic trunk that pass to the inferior hypogastric plexus; part of the abdominopelvic (sympathetic) splanchnic nerves, but their specific function is unclear. They tend to be confused with the pelvic splanchnic nerves, which are much more significant structures. Synonym: nervi splanchnici sacrales. (05 Mar 2000) |
| sacral triangle | The surface area over the sacrum. (05 Mar 2000) |
| sacral tuberosity | A rough prominence on the lateral surface of the sacrum posterior to the auricular surface for attachment of posterior sacroiliac ligaments. Synonym: tuberositas sacralis. (05 Mar 2000) |
| sacral veins | See: lateral sacral veins, median sacral vein. (05 Mar 2000) |
| sacral venous plexus | A venous plexus on the pelvic surface of the sacrum, formed by tributaries to the lateral sacral veins. Synonym: plexus venosus sacralis. (05 Mar 2000) |
| sacral vertebrae | The segments of the vertebral column, usually five in number, that fuse to form the sacrum. Synonym: vertebrae sacrales. (05 Mar 2000) |
| intermediate sacral crests | Crests formed by the fusion of articular processes of all the sacral vertebrae. Synonym: articular crests, cristae sacrales intermediae. (05 Mar 2000) |
| acoustic crest | An elevation on the inner surface of the ampulla of each saemicircular duct; filaments of the vestibular nerve pass through the crista to reach hair cells on its surface; the hair cells are capped by the cupula, a gelatinous protein-polysaccharide mass. Synonym: crista ampullaris, acoustic crest, transverse septum. (05 Mar 2000) |
| acousticofacial crest | The part of the neural crest from which the ganglia of the seventh and eighth cranial nerves develop. (05 Mar 2000) |
| alveolar crest | The portion of the alveolar bone extending beyond the periphery of the socket, lying interproximally, the top of the residual alveolar bone. (05 Mar 2000) |
| ampullary crest | An elevation on the inner surface of the ampulla of each saemicircular duct; filaments of the vestibular nerve pass through the crista to reach hair cells on its surface; the hair cells are capped by the cupula, a gelatinous protein-polysaccharide mass. Synonym: crista ampullaris, acoustic crest, transverse septum. (05 Mar 2000) |
| anterior lacrimal crest | A vertical ridge on the lateral surface of the frontal process of the maxilla that forms part of the medial rim of the orbit. Synonym: crista lacrimalis anterior. (05 Mar 2000) |