10/23: Small Intestine and Colon Flashcards
What makes up the small intestine?
Duodenum, jejunum, and ileum
What makes up the colon?
Cecum
Appendix
Ascending colon
Transverse Colon
Descending colon
Sigmoid colon
What in the small intestine is mesenteric?
Jejunum and ileum
Describe the mesenteries of the duodenum
1st segment mesenteric
2-4th are secondarily retroperitoneal
How long is the duodenum?
About a foot long
What makes up the mucosal lining of the duodenum?
Many plicae circularies
How large is the jejunum?
2/5 of intestine beyond the duodenum
Where does the jejunum start and fill up?
Starts at duodenojejunal junction and fills up most of left side
What is the mucosal lining of the jejunum?
Small amount of spread out plicae circularies
How large is the ileum?
Remaining 3/5 beyond the duodenum
What does the ileum plug ito?
Cecum at ileocecal junction
Where is the cecum located?
At lower right quadrant, first part of the large intestine
What is the mucosal lining of the ileum?
Absence of plicae circularies
Smooth wall which contains lymphoid tissue
What does the colon (large intestine) consist of?
Cecum, appendix, ascending colon, transverse colon, and sigmoid colon
What does the colon contain?
Haustrae
Appendices Epiploicae
Taenia coli
What are haustrae?
Marginal rims that gives colon scalloped appearance
What is the appendices epiploicae?
Functionless accumulated fat on outside of haustrae (enlarge as you travel towards sigmoid colon)
What is the taenia coli?
Longitudinal smooth muscle streaks found on outer surface of colon
Be able to name the colon
What does the cecum meet with?
Ileum at the first part of the large intestine
What is the appendix?
Outgrowth of cecum, found inferior to dudenojejunal junction
How long is the ascending colon and where does it run?
8-10 inches
Vertically from lower right to upper right quadrant
Runs into liver and bends
What is the ascending colon bend called?
Hepatic flexure (right colic flexure)
Where does the. transverse colon run from?
Right to left side turns downwards when it gets to spleen
What is the bend in the transverse colon called?
Splenic flexure (left colic flexure)
Where does the descending colon run?
From upper left to lower left quadrant
Where does the sigmoid colon run from?
Lower left to the midline
What is the rectum?
End of sigmoid colon, experiences contact with outside world
What is the mid gut blood supply from?
Superior mesenteric artery
What is the jejunum supplied by?
Jejunal arteries forming anastomosing loops with vasa recta branches reaching the gut itself
What is the ileum supplied by?
Ileal arteries forming anastomosing loops with vasa recta branches reacting the gut itself
What is the lower ileum supplied by?
Ileocolic artery
What is the cecum supplied by?
Ileocolic artery
What is the ascending colon supplied by?
Right colic artery which runs perpendicular and has many branches that diverge to supply ascending colon and right colin flexure
What is the transverse colon supplied by?
Middle colic artery (last 1/3 after transition supplied by ascending left colic artery where it forms last)
Where does the superior mesentery artery run in?
Root of the mesentery toward the lower right quadrant
Where does the middle colic artery run?
In transverse mesocolon
What does the middle colic artery supply?
Transverse colon first 2/3
Where does the right colic artery run?
Retroperitoneally
What does the right colic artery supply?
Ascending colon
Where does the intestinal branches (jejunal and ileal arteries) run?
Mesentary proper
What does the ileocolic artery supply?
Cecum and lower ileum
Where does the ileocolic artery run?
Retroperitoneally toward ileocecal junction
What do jejunal and ileal arteries supply?
Jejunum and ileum
What is the hind gut supply from?
Inferior mesenteric artery
What does the hind gut blood supply come from?
Inferior mesenteric artery
What is the descending colon supplied by?
Left colic artery
What does the left colic artery (LCA) branch into?
Descending and ascending branches
What is the sigmoid colon supplied by?
Sigmoid artery loops
What is the rectum supplied by?
Superior rectal artery
What runs between the jejunum and ileuM/
Mesentary proper
What runs in the mesentary proper?
Intestinal branches (jejunal and ileal arteries)
Where does the mesentary proper stop at?
Ileocecal junction because gut has now become secondarily retroperitoneal
What happens when gut loses its mesentary?
It will take its blood supply with it
i.e., retroperitoneal parts of the GI tract are supplied by retroperitoneal A and V
What mesentary contains middle colic artery?
Transverse colon
What does the middle colic artery supply?
Transverse colon
What is a triangular shaped mesentary attached to the appendix?
Mesoappendix
What does the mesoappendix contain?
Appendicular artery (branch of ileocolic)
What does the ileal branch turn into and supply?
Turns into mesentery proper; supplies the distal ileum
What is the appendicular artery?
A mesenteric branch to the appendix (in the mesoappendix)
What are the two branches of the superior mesenteric artery (SMA)?
Jejunum and ileum
What does the jejunal artery loop into?
Smaller lops called arcades
Describe the jejunal artery
- 2 arcade rows
- long vasa recti directly to organ wall
- little fat in this area “light signs through mesentery”
What does the ileal artery loop into?
Many smaller loops called arcades
Describe the ileal artery
Describe the ileal artery
- 4 arcaede rows
- short vasa recti directly to organ wall
- lots of fat
What does the inferior mesenteric artery (IMA) originate from?
The aorta at about L3 and is mostly retroperitoneal
What artery is the mostly retroperitoneal?
Left colic artery
What does the left colic artery become when it enters the transverse mesocolon?
Mesenteric to anastomose with middle colic (from SMA)
What does the left colic artery supply?
Last 1/3 of transverse colon
What does the majority of the left colic artery supply?
Descending colon
What is secondary retriperitoneal?
Descending colon
Where do the sigmoid arteries lie?
Within sigmoid mesocolon
What arteries are mesenteric?
Sigmoid arteries
What arteries are secondary retroperitoneal with the rectum?
Superior rectal artery
What do superior rectal arteries supply?
Rectum
What are inferior and superior mesenteric arteries anastomoses important for?
If arteriole blockage occurs, all areas can still be supplied
What does the middle colic a. (SMA) anastomose with?
Left colic arteries (IMA) at the left colic flexure
What does the ileocolic artery (SMA) anastomose with?
Right colic artery (SMA) near the ileocecal junction
What does the sigmoid artery (IMA) anastomose with?
The superior rectal artery (IMA) at the transition from the sigmoid colon to the rectum
Where are paramesenterics?
Posterior and superior to the mesentery proper
Where are paracolic gutters?
On outside of large intestine curves
What do paramesenteric and paracolic gutters provide?
Channels for infections within the abdominal cavity
What is an example of a channel that a paramesenteric and paracolic gutter provide?
Pus from a burst appendix (lower right quadrant) can flow up with right paracolic gutter to form an abscess in the right hepatorenal recess
