Rectum

The rectum is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. The adult human rectum is about 12 centimetres (4.7 in) long,[2] and begins at the rectosigmoid junction (the end of the sigmoid colon) at the level of the third sacral vertebra or the sacral promontory depending upon what definition is used.[3] Its diameter is similar to that of the sigmoid colon at its commencement, but it is dilated near its termination, forming the rectal ampulla. It terminates at the level of the anorectal ring (the level of the puborectalis sling) or the dentate line, again depending upon which definition is used.[3] In humans, the rectum is followed by the anal canal which is about 4 centimetres (1.6 in) long, before the gastrointestinal tract terminates at the anal verge. The word rectum comes from the Latin rectum intestinum, meaning straight intestine.

Rectum
Scheme of digestive tract, with rectum marked
Anatomy of the anus and rectum
Details
PrecursorHindgut
Part ofLarge intestine
SystemGastrointestinal system
ArterySuperior rectal artery (first two-thirds of rectum), middle rectal artery (last third of rectum)
VeinSuperior rectal veins, middle rectal veins
NerveInferior anal nerves, inferior mesenteric ganglia[1]
LymphInferior mesenteric lymph nodes, pararectal lymph nodes, internal iliac lymph nodes, Deep inguinal lymph nodes
FunctionStore feces prior to defecation
Identifiers
Latinrectum intestinum
MeSHD012007
TA98A05.7.04.001
TA22998
FMA14544
Anatomical terminology

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