| 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) |
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| 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) |
| spina ossis sphenoidalis | A posterior and downward projection from the greater wing of the sphenoid bone on either side, located posterolateral to the foramen spinosum, so-named for its proximity to the sphenoidal spine; gives attachment to the sphenomandibular ligament. Synonym: processus spinosus, spina ossis sphenoidalis, alar spine, angular spine, spina angularis, spinous process. (05 Mar 2000) |
| spina pedis | An obsolete term for a hard or soft corn. (05 Mar 2000) |
| spina peronealis | A projection from the lateral side of the calcaneus between the tendons of the peroneus longus and brevis. Synonym: trochlea peronealis, trochlea fibularis calcanei, peroneal pulley, processus trochlearis, spina peronealis, trochlear process. (05 Mar 2000) |
| spina pubis | A small projection at the anterior extremity of the crest of the pubis about 2 cm from the symphysis. Synonym: tuberculum pubicum, pubic spine, spina pubis. (05 Mar 2000) |
| spina scapulae | The prominent triangular ridge on the dorsal aspect of the scapula, providing attachment for the trapezius and deltoid muscles and separating the supra-and infraspinous fossae. Synonym: spina scapulae. (05 Mar 2000) |
| spina suprameatica | 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 trochlearis | A spicule of bone arising from the edge of the trochlear fovea, giving attachment to the pulley of the superior oblique muscle of the eyeball. Synonym: spina trochlearis. (05 Mar 2000) |
| spina tympanica major | The anterior edge of the tympanic notch (of Rivinus). Synonym: spina tympanica major. (05 Mar 2000) |