Anal canal

Anal canal
Coronal section of rectum and anal canal.
Coronal section through the anal canal. B. Cavity of urinary bladder V.D. Ductus deferens. S.V. Seminal vesicle. R. Second part of rectum. A.C. Anal canal. L.A. Levator ani. I.S. Sphincter ani internus. E.S. Sphinear ani externus.
Latin	canalis analis
Gray's	subject #249 1184
Artery	inferior rectal artery
Vein	inferior rectal vein
Lymph	superficial inguinal lymph node (below pectinate line) internal iliac lymph nodes (above line)
MeSH	Anal+Canal
Dorlands/Elsevier	c_04/12208538

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 ischiorectal fossae.

In humans it is approximately 2.5 to 4 cm long, extending from the anorectal junction to the anus. It is directed downwards and backwards. It is surrounded by inner involuntary and outer voluntary sphincters which keep the lumen closed in the form of an anteroposterior slit.

It is differentiated from the rectum by the transition of the internal surface from endodermal to skinlike ectodermal tissue.

Additional images

Anatomy of the anus and rectum	Left Levator ani from within.	The interior of the anal cami and lower part of the rectum.
Median sagittal section of female pelvis.

See also

• Anal columns
• Anal sinuses
• Anal valves
• Pectinate line

External links

• Norman/Georgetown pelvis
• SUNY Figs 44:05-00 - "The rectum and anal canal in the male pelvis."
• Anal+canal at eMedicine Dictionary

Anatomy of torso, digestive system: Gastrointestinal tract
Upper GI: to stomach	Mouth • Pharynx (nasopharynx, oropharynx, hypopharynx) • Esophagus • Crop
Upper GI: stomach	rugae - gastric pits - cardia/gland - fundus/gland - pylorus/gland - pyloric antrum - greater curvature - lesser curvature
Lower GI: intestines	Small intestine (duodenum, jejunum, ileum) • Vermiform appendix • Ileocecal valve - Large intestine: Cecum • Colon (ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon)
Lower GI: after intestines	Rectum (Houston valve, rectal ampulla, pectinate line) • Anal canal (anal valves, anal sinuses, anal columns) - Anus: Sphincter ani internus muscle • Sphincter ani externus muscle
Lower GI: continuous	GALT: Peyer's patches • M cells - intestinal villus • crypts of Lieberkühn • circular folds • taenia coli • haustra • epiploic appendix