Definition

Noun: * Internal anal sphincter muscle: An internal ring of smooth muscle formed by circular fibers of the rectum. It is an involuntary muscle that helps maintain continence.

Usage

This is a highly specific anatomical term. It is used primarily in medical, biological, and anatomical contexts to describe a precise structure in the human body. * The musculus sphincter ani internus is composed of smooth muscle, meaning its function is automatic and not under conscious control. * Damage to the musculus sphincter ani internus can contribute to fecal incontinence. * The surgical procedure aimed to repair the torn musculus sphincter ani internus.

Advanced Usage

• The term is often discussed in contrast to the (musculus sphincter ani externus), which is composed of skeletal muscle and is under voluntary control. Together, they form the anal sphincter complex responsible for bowel control.
• In medical literature, it may be abbreviated as IAS.

Variants and Related Words

• Internal anal sphincter (IAS): The common clinical and simplified term for .
• Sphincter: (Noun) A ring-shaped muscle that normally maintains constriction of a natural body passage or orifice and relaxes as required by normal physiological functioning.
• Smooth muscle: (Noun) Muscle tissue in which the contractile fibrils are not highly ordered, occurring in the walls of internal organs such as the rectum, stomach, and blood vessels, and not under voluntary control.

Synonyms

• Internal anal sphincter
• IAS

Note: There are no common idioms or phrasal verbs associated with this precise anatomical term.

Noun

1. an internal ring of smooth muscle formed by circular fibers of the rectum