Anal triangle is the posterior perineal region containing the anal canal and its sphincters.
The anal triangle is the posterior portion of the perineum, containing the anal canal, surrounding muscles, fascia, and neurovascular structures. It is one of the two subdivisions of the perineum (the other being the urogenital triangle), and it plays an essential role in fecal continence and defecation. The triangle is defined by bony and ligamentous landmarks and contains the ischioanal fossae, which provide space for the expansion of the anal canal during defecation.
The anal triangle is a fat-filled, wedge-shaped region containing the terminal part of the gastrointestinal tract and supporting soft tissues. It is primarily composed of the anal canal, the external anal sphincter, ischioanal fossae, and associated vessels and nerves.
The ischioanal fossae are paired, wedge-shaped fat-filled spaces that lie on either side of the anal canal. They allow for expansion of the canal during defecation and are traversed by neurovascular structures supplying the anal region.
The anal triangle lies posteriorly in the perineum and is positioned between the thighs and buttocks, below the pelvic diaphragm. It is best visualized with the patient in the lithotomy or prone position.
Direction | Related Structures |
---|---|
Superior | Levator ani muscle and pelvic diaphragm |
Inferior | Skin of the perianal region |
Anterior | Urogenital triangle (perineal body marks the division) |
Lateral | Ischial tuberosities and obturator internus muscle (via ischioanal fossa) |