| plexus sacralis medius | A lymphatic plexus formed of lymph nodes and connecting vessels situated chiefly in the mesorectum anterior and inferior to the sacral promontory. Synonym: plexus sacralis medius. (05 Mar 2000) |
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| plexus venosus sacralis | 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) |
| crista sacralis | One of three rough irregular ridges on the posterior surface of the sacrum; median sacral crest; lateral sacral crests. Synonym: crista sacralis. (05 Mar 2000) |
| crista sacralis mediana | An unpaired crest formed by the fused spinous processes of the upper four sacral vertebrae. Synonym: crista sacralis mediana. (05 Mar 2000) |
| hiatus sacralis | A normally-occurring gap at the lower end of the sacrum, exposing the vertebral canal, due to failure of the laminae of the last sacral segment to coalesce. It is closed by the sacrococcygeal ligament, and provides cannular access to the sacral epidural space for administration of anaesthetics (caudal nerve blocks). Synonym: hiatus sacralis. (05 Mar 2000) |
| hiatus totalis sacralis | Developmental clefting in all sacral vertebrae; may also involve adjacent lumbar vertebrae. (05 Mar 2000) |
| tuberositas sacralis | 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) |