Anal triangle
Encyclopedia
The anal triangle is the posterior part of the perineum
. It contains the anal canal
.
or its sides.
Perineum
In human anatomy, the perineum is a region of the body including the perineal body and surrounding structures...
. It contains the anal canal
Anal canal
The anal canal is the terminal part of the large intestine.It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischioanal fossa....
.
Structure
The anal triangle can be defined either by its verticesVertex (geometry)
In geometry, a vertex is a special kind of point that describes the corners or intersections of geometric shapes.-Of an angle:...
or its sides.
- Vertices
- one vertex at the coccyxCoccyxThe coccyx , commonly referred to as the tailbone, is the final segment of the vertebral column. Comprising three to five separate or fused vertebrae below the sacrum, it is attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between...
bone - the two ischial tuberosities of the pelvic bone
- one vertex at the coccyx
- Sides
- perineal membranePerineal membraneThe perineal membrane is an anatomical term for a fibrous membrane in the perineum. The term "inferior fascia of urogenital diaphragm", used in older texts, is considered equivalent to the perineal membrane....
(posterior border of perineal membrane forms anterior border of anal triangle) - the two sacrotuberous ligaments
- perineal membrane
Contents
Some components of the anal triangle include:- Ischioanal fossa
- Sacrotuberous ligamentSacrotuberous ligamentThe sacrotuberous ligament is situated at the lower and back part of the pelvis. It is flat, and triangular in form; narrower in the middle than at the ends....
- Sacrospinous ligamentSacrospinous ligament-External links: - "Posterior view of the bones and ligaments of the hip joint."*...
- Pudendal nervePudendal nerveThe pudendal nerve is a sensory and somatic nerve in the pelvic region which is a large branch of the sacral plexus that innervates the external genitalia of both sexes, as well as sphincters for the bladder and the rectum...
- Internal pudendal arteryInternal pudendal arteryThe internal pudendal artery is an artery that branches off the internal iliac artery, providing blood to the external genitalia.The internal pudendal artery is the terminal branch of the anterior trunk of the internal iliac artery...
and Internal pudendal vein - Anal canalAnal canalThe anal canal is the terminal part of the large intestine.It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischioanal fossa....
- Muscles
- Sphincter ani externus muscleSphincter ani externus muscleThe Sphincter ani externus is a flat plane of muscular fibers, elliptical in shape and intimately adherent to the integument surrounding the margin of the anus.-Anatomy:...
- Gluteus maximus muscleGluteus maximus muscleThe gluteus maximus is the largest and most superficial of the three gluteal muscles...
- Obturator internus muscleObturator internus muscleThe obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, and the rim of the pubis.It exits the pelvic cavity through the lesser sciatic foramen....
- Levator ani muscle
- Coccygeus muscleCoccygeus muscleThe Coccygeus is a muscle of the pelvic wall , located posterior to levator ani and anterior to the sacrospinous ligament....
- Sphincter ani externus muscle