anorectal flexure

(redirected from anorectal angle)

a·no·rec·tal flex·ure

[TA]
the anteroposterior curve or angle, with convesity directed anteriorly, of the anorectal junction; tonus of the puborectalis (muscle) produces the angle for maintaining fecal continence; relaxation of the muscle allows the angle to be reduced for defecation.

anorectal flexure

The sharp forward bend at the anorectal junction as the rectum passes through the pelvic diaphragm muscles. This acute bend, which is normally maintained by the puborectalis sling muscles, helps to keep feces in the rectum. During defecation the pelvic diaphragm muscles relax (so the puborectalis sling relaxes) and the sharp bend between rectum and anus straightens; this makes the passage of feces from rectum to anus easier.
See also: flexure
References in periodicals archive ?
4) The muscles of the pelvic floor normally maintain the anorectal angle.
Through both still images and a dynamic series of images as the patient defecates, defecography shows the anorectal angle, which is a function of the levator ani.
The puborectalis muscle surrounding the anorectal junction then relaxes to allow the straightening of the anorectal angle.
It accentuates the action of the puborectalis by also pulling the anorectal junction forward anteriorly to further increase the anorectal angle.
The anorectal angle is the angle formed between the axis of the anal canal and the rectum.
A flap of anterior rectal mucosa that lies over the upper end of the anal canal is thought to function as a flap-valve, opening when the puborectal muscle relaxes so that the anorectal angle is obliterated, permitting defecation to occur.
In particular, rectocele, moderate degrees of intussusception and increased anorectal angle may be seen in some normal individuals.
Furthermore, defecography is limited in the measurement of the anorectal angle because of significant interobserver variability in assessing the angle.
During normal defecation, the external sphincter relaxes, the anorectal angle straightens and increased intra-abdominal pressure results in the expulsion of fecal matter.
With defecography, the anorectal angle may appear to be narrow and does not widen upon straining.
Defecography also provides information about the movement of the pelvic floor, the anorectal angle and the puborectalis sling during evacuation, squeezing and rest.
The anorectal angle -- the angle between the anis of the anal canal and the rectum -- usually is measured.