Colon & Rectum Flashcards
(189 cards)
Foregut structures extend all the way to?
2nd part of duodenum
rely on celiac artery
Midgut structures of abdomen?
extends from duodenal ampulla to distal tranverse colon (rely on SMA)
Hindgut structures?
distal third of t-colon, descending colon, rectum
rely on IMA
Avg. diameter and length of cecum?
diameter is 7.5 cm
length approx. 10 cm
Acute dilatation of cecum greater than what number can result in acute ischemic necrosis and bowel perforation?
> 12 cm
Most common location of appendix in relation to the cecum?
retrocecal 65% of time
pelvic 30% of time
These two parts of the colon are retroperitoneal in nature:
ascending + descending colon
How do we mobilize the colon and its mesentery from the retroperitoneum?
dissect along the white line of Toldt
What is the white line of Toldt?
represents the fusion of the mesentery with the posterior peritoneum
What ligaments tether the colon to the hepatic flexure and the splenic flexures?
hepatic flexure; nephrocolic ligament
splenic flexure; phrenocolic ligament
How do we get to the splenic flexure when mobilizing the colon?
dissecting the descending colon upward via white line of Toldt
then lesser sac is entered by reflecting the omentum away from t-colon
Attached to anterior surface of t-colon is greater omentum, which has how many layers?
fused double layer of parietal and visceral peritoneum (4 layers)
contains stored fat
The descending colon, lies ventral to left kidney and extends downward for how long?
25 cm
Where do we see a transition from the thin walled, fixed, descending colon to the mobile sigmoid colon?
level of pelvic brim
In relation to the sigmoid colon, it has a long floppy mesentery, often attached to left pelvic sidewall, producing a small recess called the intersigmoid fossa, often a landmark for what?
left ureter
Rectum along with sigmoid serve as what?
fecal reservoir
The rectum is usually 12-15 cm in length usually lacks what?
tenia coli and appeploic appendages
Why do we say the rectum posterior surface is almost completely extraperitoneal?
its adherent to presacral soft tissues, thus outside the peritoneal cavity
Anterior surface of proximal third of rectum covered by visceral peritoneum, what is this anterior space called?
Pouch of Douglas
What’s the pouch of douglas?
recto-uterine pouch
can serve as site of drop mets from visceral tumors
What’s Bloomer’s shelf?
drop mets from visceral tumors can fall into the pouch of Douglas and form a mass there
often detected by digital rectal exam
Rectum possesses three curves or involutions, known as?
valves of Houston
have no function, don’t impede flow
usually lost after surgical mobilization of rectum
Mobilization of rectum leads to loss of the 3 rectal curves called the valves of Houston, thus adding how much extra rectal tissue?
approx. 5 cm
great for anastomosing in the pelvis
The rectum is intimately close to the presacral fascia, but it is not directly adhered to it, what separates it?
posterior aspect of rectum covered by mesorectum and the mesorectum covered by a thin layer of investing fascia called fascia propria
fascia propria prevents direct rectal adherence to presacral fascia
serves as a bloodless plane for oncologic rectal surgery