| musculus sphincter ani externus | A fusiform ring of striated muscular fibres surrounding the anus, attached posteriorly to the coccyx and anteriorly to the central tendon of the perineum; it is subdivided, often indistinctly, into a subcutaneous part, a superficial part and a deep part for descriptive purposes. Synonym: musculus sphincter ani externus, external sphincter muscle of anus. (05 Mar 2000) |
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| musculus sphincter ductus choledochi | Smooth muscle sphincter of the common bile duct immediately proximal to the hepatopancreatic ampulla; it is this sphincter that controls the flow of bile in the duodenum. Synonym: musculus sphincter ductus choledochi, Boyden's sphincter, choledochal sphincter, sphincter muscle of common bile duct. (05 Mar 2000) |
| musculus sphincter ductus pancreatici | Smooth muscle sphincter of the main pancreatic duct immediately proximal to the hepatoduodenal, ampulla. Synonym: musculus sphincter ductus pancreatici, pancreatic sphincter, sphincter muscle of pancreatic duct. (05 Mar 2000) |
| musculus sphincter oris | <anatomy, muscle> Origin, by nasolabial band from septum of the nose, by superior incisive bundle from incisor fossa of maxilla, by inferior incisive bundle from lower jaw each side of symphysis; insertion, fibres surround mouth between skin and mucous membrane of lips and cheeks, and are blended with other muscles; action, closes lips; nerve supply, facial. Synonym: musculus orbicularis oris, musculus sphincter oris, orbicular muscle of mouth, sphincter oris. (05 Mar 2000) |
| musculus sphincter pupillae | A ring of smooth muscle fibres surrounding the pupillary border of the iris. Synonym: musculus sphincter pupillae, sphincter muscle of pupil. (05 Mar 2000) |
| musculus sphincter pylori | 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) |
| 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) |
| 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) |
| arteria bulbi urethrae | A branch of the internal pudendal artery which supplies the bulb of the penis including the bulbar urethra. Synonym: arteria bulbi penis, arteria bulbi urethrae. (05 Mar 2000) |
| bulbus urethrae | The expanded posterior part of the corpus spongiosum of the penis lying in the interval between the crura of the penis. Synonym: bulbus penis, bulb of corpus spongiosum, bulb of urethra, bulbus urethrae. (05 Mar 2000) |
| pars membranacea urethrae masculinae | The portion of the male urethra, about 1 cm in length, extending from the prostate to the beginning of the urethra in the corpus spongiosum just beyond the bulb. Synonym: pars membranacea urethrae masculinae, membranous urethra. (05 Mar 2000) |
| pars prostatica urethrae | The prostatic part of the male urethra, about 2.5 cm in length, that traverses the prostate; it includes the seminal colliculus, and the ejaculatory and prostatic ducts open into it. Synonym: pars prostatica urethrae. (05 Mar 2000) |
| pars spongiosa urethrae masculinae | The portion of the male urethra, about 15 cm in length, which traverses the corpus spongiosum. Synonym: pars spongiosa urethrae masculinae, pars cavernosa, penile urethra, spongy part of the male urethra. (05 Mar 2000) |
| corpus cavernosum urethrae | The median column of erectile tissue located between and ventral to the two corpora cavernosa penis; posteriorly it expands into the bulbus penis and anteriorly it terminates as the enlarged glans penis; it is traversed by the urethra. Synonym: corpus cavernosum urethrae, spongy body of penis. Corpus spongiosum urethrae muliebris, the submucous coat of the female urethra, containing a venous network that insinuates itself between the muscular layers, giving to them an erectile nature. (05 Mar 2000) |
| hemispherium bulbi urethrae | One of the lateral halves of the bulb of the penis that are separated by a median groove on the posterior part of the undersurface. Synonym: hemispherium bulbi urethrae. (05 Mar 2000) |