Search results
Results from the WOW.Com Content Network
The internal anal sphincter, IAS, or sphincter ani internus is a ring of smooth muscle that surrounds about 2.5–4.0 cm of the anal canal. It is about 5 mm thick, and is formed by an aggregation of the smooth (involuntary) circular muscle fibers of the rectum. It terminates distally about 6 mm from the anal orifice. [citation needed]
The internal urethral sphincter is a urethral sphincter muscle which constricts the internal urethral orifice. It is located at the junction of the urethra with the urinary bladder and is continuous with the detrusor muscle, [1][2] but anatomically and functionally fully independent from it. [3] It is composed of smooth muscle, so it is under ...
The internal sphincter is a continuation of the detrusor muscle and is made of smooth muscle, therefore it is under involuntary or autonomic control. This is the primary muscle for prohibiting the release of urine. The female or male external sphincter muscle of urethra (sphincter urethrae): located in the deep perineal pouch, at the bladder's ...
The external urethral sphincter is a striated muscle that allows voluntary control over urination. [4] The internal sphincter, formed by the involuntary smooth muscles lining the bladder neck and urethra, receives its nerve supply by the sympathetic division of the autonomic nervous system. [5] The internal sphincter is present both in males ...
The internal anal sphincter (an involuntary muscle) responds to the pressure by relaxing, thus allowing the feces to enter the canal. The rectum shortens as feces are pushed into the anal canal and peristaltic waves push the feces out of the rectum.
Lateral internal sphincterotomy is an operation performed on the internal anal sphincter muscle for the treatment of chronic anal fissure. The internal anal sphincter is one of two muscles that comprise the anal sphincter which controls the passage of feces. The procedure helps by lowering the resting pressure of the internal anal sphincter ...
Transphincteric fistulae begin between the internal and external sphincter muscles or behind the anus, cross the external sphincter muscle and open an inch or more away from the anus. [3] [9] [10] These may take a 'U' shape and form multiple external openings. This is sometimes termed a 'horseshoe fistula.' [2]
Proctalgia fugax. Specialty. General surgery. Proctalgia fugax, a variant of levator ani syndrome, is a severe, episodic pain in the regions of the rectum and anus. [1] It can be caused by cramping of the levator ani muscle, particularly in the pubococcygeal part. [2]