| 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) |
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| 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) |
| lateral sacral artery | <anatomy, artery> Usually one of two arteries which arise from the internal iliac artery or its branches; they supply muscles and skin in the neighborhood and send branches into the sacral canal, supplying radicular and spinal arteries, and continuing on to the skin and subcutaneous tissues overlying the sacrum. Synonym: arteria sacralis lateralis. (05 Mar 2000) |
| lateral sacral crests | Crests which are rough ridges lying lateral to the sacral foramina; they represent the fused transverse processes of sacral vertebrae. Synonym: cristae sacrales laterales. (05 Mar 2000) |
| lateral sacral veins | Several veins that receive the drainage of the sacral venous plexus and sacral intervertebral veins then accompany the corresponding artery and empty into the internal iliac vein on each side. Synonym: venae sacrales laterales. (05 Mar 2000) |
| abdominocardiac reflex | Mechanical stimulation (usually distention) of abdominal viscera causing changes (usually a slowing) in the heart rate or the occurrence of extrasystoles. (05 Mar 2000) |
| Abrams' heart reflex | A contraction of the myocardium when the skin of the precordial region is irritated. (05 Mar 2000) |
| accommodation reflex | Increased convexity of the lens, due to contraction of the ciliary muscle and relaxation of the suspensory ligament, to maintain a distinct retinal image. (05 Mar 2000) |
| Achilles reflex | A contraction of the calf muscles when the tendo calcaneus is sharply struck. Synonym: ankle jerk, ankle reflex, tendo Achillis reflex, triceps surae reflex. (05 Mar 2000) |
| acousticopalpebral reflex | A form of the wink reflex in which there is a contraction, sometimes very slight, of the orbicularis palpebrarum muscle when a sudden noise is made close to the ear; it is absent in labyrinthine disease with total deafness. Synonym: acousticopalpebral reflex, auropalpebral reflex, cochleo-orbicular reflex, startle reflex. (05 Mar 2000) |