| musculus sphincter vaginae | <anatomy> In the male: origin, the perineal membrane fascia on the dorsum of the bulb of the penis; insertion, central tendon of the perineum and the median raphe on the free surface of the bulb; action, constricts bulbous urethra when attempting to expel last drops following urination, or spasmodically with ejaculation to expel semen. In the female: origin, the dorsum of the clitoris, the corpus cavernosum, and the perineal membrane; insertion, central tendon of the perineum; action, acts as a weak sphincter of the vagina; when developed, is a part of "cross-member musculature" of pelvic floor which resists prolapse of pelvic viscera. Nerve supply, pudendal (deep perineal branch). Synonym: musculus bulbospongiosus, musculus bulbocavernosus, musculus ejaculator seminis, musculus sphincter vaginae, sphincter vaginae. (05 Mar 2000) |
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| musculus sphincter vesicae | The complete collar of smooth muscle cells of the neck of the urinary bladder which extend distally to surround the preprostatic sportion of the male urethra. There is not a comparable structure in the neck of the femoral bladder; the internal urethral sphincter may exist to prevent reflux of semen into bladder. Synonym: annulus urethralis, internal urethral sphincter, musculus sphincter vesicae, preprostate urethral sphincter, proximal urethral sphincter, sphincter muscle of urinary bladder. (05 Mar 2000) |
| myovascular sphincter | A sphincter having a muscular and a vascular (usually venous) component. See: myovenous sphincter. (05 Mar 2000) |
| myovenous sphincter | A sphincter having a muscular and a venous component, e.g., at the pharyngoesophageal junction and anal canal. (05 Mar 2000) |
| postpyloric sphincter | The duodenal portion of the sphincter or closing mechanism of the gastroduodenal pylorus. (05 Mar 2000) |
| prepapillary sphincter | A sphincter of duodenum described in the location oral to the major duodenal papilla. (05 Mar 2000) |
| prepyloric sphincter | A band of circular muscular fibres in the wall of the stomach near the gastroduodenal pylorus. (05 Mar 2000) |
| hepatopancreatic sphincter | The smooth muscle sphincter of the hepatopancreatic ampulla within the duodenal papilla. Synonym: musculus sphincter ampullae hepatopancreaticae, Glisson's sphincter, hepatopancreatic sphincter, Oddi's sphincter. (05 Mar 2000) |
| segmental sphincter | A sphincter of a segment of an organ, a tube, or a canal, and longer than an annular sphincter. (05 Mar 2000) |
| pyloric sphincter | A thickening of the circular layer of the gastric musculature encircling the gastroduodenal junction. Synonym: musculus sphincter pylori, sphincter muscle of pylorus. (05 Mar 2000) |
| Hyrtl's sphincter | A band, generally incomplete, of circular muscular fibres in the rectum about 10 cm above the anus (upper rectal ampulla). See: Nelaton's sphincter. (05 Mar 2000) |
| smooth muscular sphincter | A sphincter of smooth musculature. Synonym: smooth muscular sphincter. Origin: G. Lissos, smooth, + sphincter (05 Mar 2000) |
| sphincter | <anatomy> A ringlike band of muscle fibres that constricts a passage or closes a natural orifice, also called musculus sphincter. Origin: L., Gr. Sphinkter = that which binds tight (18 Nov 1997) |
| sphincter angularis | Angular sphincter, thickening of the circular muscular layer forming a proposed intermediate sphincter at the level of the angular notch of the stomach. While the thickening of the circular muscle may indicate the commencement of the pyloric antrum, true functional sphincteric activity distinct from the other peristaltic contractions of the stomach is not observed although some of these may in fact temporarily close off the antrum from the remainder of the stomach lumen. Synonym: antral sphincter, midgastric transverse sphincter, sphincter antri, sphincter intermedius, sphincter of antrum, sphincter of gastric antrum. (05 Mar 2000) |
| sphincter ani tertius | The third sphincter of the anorectum, a physiological sphincter at the sigmoidorectal junction. (05 Mar 2000) |