RECTUM Flashcards
what is the distribution of peritoneum on the rectum
the first third - anterior and lateral
second third - anterior aspect
last third - none as it is subperitoneal
where is the rectosigmoid junction and what is it’s significance?
15 cm from the anus and this is where the tenaie coli terminate and join together to form one continuous band of muscle
what is the blood supply to the rectum?
proximal 2/3 are hindgut derivatives so get their blood supply from the superior rectal veins which branch from the IMV
the distal 1/3 is from the right and left middle and right and left inferior rectal arteries which come from the commom iliac arteries
venous drainage of the rectum
superior, middle and inferior rectal veins which drain into the imv. this is the site of one of the portosystemic anastomoses. the superior rectal vein anastomoses with a branch from the common iliac vein.
where does the anal canal begin?
point where rectal ampulla narrows at the level of the u shaped sling formed by the puborectalis muscle
where does the anal canal end?
at the anus
how many sphincters does the anal canal have?
two sphincters, internal and external both of which must be relaxed fro defecation to occur.
where are the terminal branches of the superior rectal veins found?
internally, the superior 2/3 of the anal canal’s mucus membranes is characterised by lonigtudinal ridges called anal columns. these contain the terminal branches of the superior rectal veins
where is the anorectal junction?
indicated by the superior end of the anal columns. at this point the rectal ampulla abruptly narrows as it goes through the pelvic diaphragm
where are anal valves located and what is superior to them?
anal valves are located at the inferior ends of anal columns and auperior to them are anal sinuses which secrete mucus when compressed by faeces which aids in it’s evacuation
innervation to the anal canal
above the pectinate line - visceral which tarvel with parasympathetic fibres to spinal sensory ganglia from s2-s4 so pain is referred
below - somatic - inferior is from the pudendal so pain is well localised
where is the rectouterine pouch?
in females, after the second 1/3 of the rectum, the peritonuem reflects onto the posterior part of the fornix of the vagina to form the floor of the rectouterine pouch
where is the vesicouterine pouch?
in females this is the reflection of the pritoneum between the bladder and the vagina
where is the rectovesicle pouch?
after the second 1/3 of the rectum in males, the peritoneum reflect onto the posterior surface of the bladder forming the floor of the rectovesicle pouch
