Rectum Flashcards
what is the role of the rectum
important role as a temporary store of faeces.
where does the rectum begin
s3
how is the rectum macrosopically diff from colon
important role as a temporary store of faeces.
how is the course of the rectum marked by
by two major flexures:
Sacral flexure – anteroposterior curve with concavity anteriorly (follows the curve of the sacrum and coccyx).
Anorectal flexure – anteroposterior curve with convexity anteriorly. This flexure is formed by the tone of the puborectalis muscle, and contributes significantly to faecal continence.
There are additionally three lateral flexures (superior, intermediate and inferior), which are formed by transverse folds of the internal rectum wall.
what happens at The final segment of the rectum, the ampulla
relaxes to accumulate and temporarily store faeces until defecation occurs. It is continuous with the anal canal; which passes through the pelvic floor to end as the anus.
what are the pertoneal coverings of the retum
In the superior third of the rectum, the anterior surface and lateral sides are covered by peritoneum. The middle third only has an anterior peritoneal covering, and the lower 1/3 has no peritoneum associated with it.
In males, the reflection of peritoneum from the rectum to the posterior bladder wall forms the rectovesical pouch. In females, the peritoneum reflects to the posterior vagina and cervix, forming the rectouterine pouch (pouch of Douglas).
what is anterior in males
rectovesical pouch Sigmoid colon ileum bladder prostate siminal vesicles
what is anterior in females
Rectouterine pouch Sigmoid colon ileum vagina cervix
what is posterior in amel and female
Sacrum and coccyx
Piriformis
Coccygeus
Levator ani
Sacral plexus
where is the rectum located
the pelvic cavity, and is the most posterior of the pelvic viscera
lymph drainage of the rectum
Lymphatic drainage of the rectum is via the pararectal lymph nodes, which drain into the inferior mesenteric nodes.
Additionally, the lymph from the lower aspect of the rectum drains directly into the internal iliac lymph nodes.
innervation of teh rectum
The rectum receives sensory and autonomic innervation.
Sympathetic nervous supply to the rectum is from the lumbar splanchnic nerves and superior and inferior hypogastric plexuses. Parasympathetic supply is from S2-4 via the pelvic splanchnic nerves and inferior hypogastric plexuses. Visceral afferent (sensory) fibres follow the parasympathetic supply.
venous draiage of the rectum
Venous drainage is via the corresponding superior, middle and inferior rectal veins. The superior rectal vein empties into the portal venous system, whilst the middle and inferior rectal veins empty into the systemic venous system. Anastomoses between the portal and systemic veins are located in the wall of anal canal, making this a site of portocaval anastomosis.
arterial supply of th rectum
The rectum receives arterial supply through three main arteries:
Superior rectal artery – terminal continuation of the inferior mesenteric artery.
Middle rectal artery – branch of the internal iliac artery.
Inferior rectal artery – branch of the internal pudendal artery.
