| spina bifida cystica | A bony defect in the vertebral column through which the meningeal membranes that cover the spinal cord and part of the spinal cord protrude. An alternative term is meningomyelocele. (12 Dec 1998) |
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| spina bifida manifesta | A bony defect in the vertebral column through which the meningeal membranes that cover the spinal cord and part of the spinal cord protrude. An alternative term is meningomyelocele. (12 Dec 1998) |
| spina bifida occulta | Literally, a hidden cleft in the spine. A bony defect in the vertebral column which remains hidden, covered by skin (12 Dec 1998) |
| spina dorsalis | The series of vertebrae that extend from the cranium to the coccyx, providing support and forming a flexible bony case for the spinal cord. Synonym: columna vertebralis, backbone, dorsal spine, rachis, spina dorsalis, spina, spina, spinal column, spine, vertebrarium. (05 Mar 2000) |
| spina frontalis | S, nasalis ossis frontalis. (05 Mar 2000) |
| spina iliaca anterior inferior | Spine on the anterior border of the ilium between the anterior superior iliac spine and the acetabulum; site of origin for the direct head of the rectus femoris muscle. Synonym: spina iliaca anterior inferior. (05 Mar 2000) |
| spina iliaca anterior superior | The anterior extremity of the iliac crest, which provides attachment for the inguinal ligament and the sartorius muscle. Synonym: spina iliaca anterior superior. (05 Mar 2000) |
| spina iliaca posterior inferior | Spine at the inferior end of the posterior border of the ilium between the posterior superior iliac spine and the greater sciatic notch; it forms the upper margin of the latter. Synonym: spina iliaca posterior inferior. (05 Mar 2000) |
| spina iliaca posterior superior | The posterior extremity of the iliac crest, the uppermost point of attachment of the sacrotuberous and posterior sacroiliac ligaments; a readily apparent dimple occurs in the skin overlying the posterior superior iliac spine which is clinically useful as an indication of the level of the S-2 vertebra, the level of the inferior limit of the subarachnoid space. Synonym: spina iliaca posterior superior. (05 Mar 2000) |
| spina ischiadica | A pointed process from the posterior border of the ischium on a level with the lower border of the acetabulum; gives attachment to the 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. Synonym: spina ischiadica, ischiadic spine, sciatic spine. (05 Mar 2000) |
| spina meatus | Small bony prominence anterior to the supramastoid pit at the posterosuperior margin of the bony external acoustic meatus. Synonym: spina suprameatica, Henle's spine, meatal spine, spina meatus. (05 Mar 2000) |
| spina mentalis | A slight projection, sometimes two, in the middle line of the posterior surface of the body of the mandible, giving attachment to the geniohyoid muscle (below) and the genioglossus (above). Synonym: spina mentalis, genial tubercle. (05 Mar 2000) |
| spina nasalis anterior | A pointed projection at the anterior extremity of the intermaxillary suture; the tip, as seen on a lateral cephalometric radiograph, is used as a cephalometric landmark. Synonym: spina nasalis anterior. (05 Mar 2000) |
| spina nasalis ossis frontalis | A projection from the centre of the nasal part of the frontal bone, which lies between and articulates with the nasal bones and the perpendicular plate of the ethmoid. Synonym: spina nasalis ossis frontalis. (05 Mar 2000) |
| spina nasalis posterior | The sharp posterior extremity of the nasal crest of the hard palate. Synonym: spina nasalis posterior, posterior palatine spine. (05 Mar 2000) |