Anal triangle

The anal triangle is the posterior part of the perineum. It contains the anus in mammals.

Anal triangle
Muscles of male perineum. (Anal triangle is roughly equal to bottom half of diagram.)
Muscles of the female perineum. (Anal triangle is roughly equal to bottom half of diagram.)
Details
Identifiers
Latin	regio analis
TA98	A01.2.06.002
TA2	278
FMA	20347
Anatomical terminology

Structure

The anal triangle can be defined either by its vertices or its sides.

• Vertices
  • one vertex at the coccyx bone
  • the two ischial tuberosities of the pelvic bone
• Sides
  • perineal membrane (posterior border of perineal membrane forms anterior border of anal triangle)
  • the two sacrotuberous ligaments

Contents

Some components of the anal triangle include:

• Ischioanal fossa
• Anococcygeal body
• Sacrotuberous ligament
• Sacrospinous ligament
• Pudendal nerve
• Internal pudendal artery and internal pudendal vein
• Anal canal
• Muscles
  • Sphincter ani externus muscle
  • Gluteus maximus muscle
  • Obturator internus muscle
  • Levator ani muscle
  • Coccygeus muscle

Additional images

• 
  Articulations of pelvis. Posterior view.
• 
  The superficial branches of the internal pudendal artery.
• 
  The posterior aspect of the rectum exposed by removing the lower part of the sacrum and the coccyx.

See also

• Perineum
• Urogenital triangle

External links

• Anatomy photo:41:01-0202 at the SUNY Downstate Medical Center - "The Female Perineum: Boundaries of the Female Perineum"
• perineum at The Anatomy Lesson by Wesley Norman (Georgetown University) (perineumboundaries)