Anal Stenosis :

When a tubular organ or blood vessel, or tubular organ becomes excessively narrow, such that it can no longer perform as nature intended, it is a condition referred to by physicians as stenosis. Anal stenosis, also known as an anal stricture, is the narrowing of the anal canal, located just before the anal sphincter.

The anal sphincter is a complex part of the body that maintains a seal that can be opened to discharge body waste. It is strong enough to restrict the passage of any fecal material but sensitive enough to differentiate between solid, liquid, and gas. There are actually two anal sphincter muscles … the internal anal sphincter and the external anal sphincter.

The internal anal sphincter is a thin, white muscle wrapped around the anal canal. The internal sphincter contracts during rest and sleep, and keeps small amounts of liquid and gas from escaping unexpectedly. The internal anal sphincter is an involuntary smooth muscle, like the muscles of your intestines. You cannot mentally control it.