Midgut- Hindgut Flashcards
Mindgut
why is it different from the rest of GI tract
blood supply?
portion of the GI track forming most of the intestines
developmentally different from other parts of GI
different blood supply (SMA)
contains: duodenum (distal 1/2), jejunum, ileum, cecum &appendix, ascending colon, transverse colon (proximal 2/3)
Hindgut
why is it different from the rest of GI tract
blood supply
distal portion of the GI track
is development distinct from other parts of GI
difference reflected in blood supply (IMA)
content: tranverse colon (distal 1/3), sigmoid colon, rectum, anal canal (upper part)
Duodenum: location
gerneral
intraperitoneal or retroperitoneal
midgut C-shaped around head of pancreas located above umbilicus retroperitoneal, except for its 1st portion
Duodenum: 4 parts anatomy
1st sup. part: level of L1, is connected with hepatoduodenal ligament (part of lesser omentum)
2nd descending part, L1-3
site of junction of foregut & midgut
3rd inf part crosses IVC and aorta. SMA pass over it
4th ascending & part, upper L2 ends into the duodenojejunal flexure
Duodenum: arterial supply
first 2 parts:
superior pancreaticoduodenal ant. & post.: branches from gastroduodenal A.
last 2 parts:
inferior pancreaticoduodenal: Ant & Post., branches from SMA
venous drainage: same
innervation: same as stomach
Jejunum
function
location
from where to where
2nd portion of small intestine makes the proximal 2/5 of small intestine specialized in nutrients absorption location: upper left quadrant from: duodenum at duodenojejunal flexure made supsensory muscle (or ligament) of duodenum (Treitz) all suspended in mesentery to ileum, no clear anatomical difference
jejunum:
anatomy
plicae circulares: numerous circular folds in its lumen (increase surface area for absorption)
arterial supply distribution: less prominent arterial arcades and long vasa recta
ileum
general
location
final section of the small intestine
make distal 3/5 of small intestine
longer than jejunum
ileum:
anatomical distinction
contains lymphoid nodules (Peyer’s patches)
plicae circulares: low & sparse
denser arterial arcades & shorter vasa recta
mesentery of small intestine
ileum & jejunum are suspended in mesentery
peritoneal fold that carries blood vessels, lymphatics & nerve fibers
small intestine: arterial supply
from SMA
giving jejunal& ileal arteries
ending in arterial arcades & vasa recta
meckel’s diverticulum
embryological remnant
ileum is connected to umbillicus (vitelline duct )
2% of duct fails to close
can stay asymptomativebut cal lead to painless rectal bleeding (melaena) and intestinal obstruction
large intestine: overal location
1.5m long
extends from cecum to anal canal
converts liquid feces to semisolid state
absorb water, salt& electrolytes
large intestine:
composed of?
midgut: Cecum appendix colon: ascending, 1/2 of transverse hindgut: colon (1/2 transverse, descending, sigmoid) rectum anal canal
large intestine:
characteristics
flexures: right colic flexure (hepatic flexure) left colic (splenic flexure)
taeniae coli: longitudinal band of muscle fibers
omental appendices: peritoneal covered fat lobules
haustra of colon: pouches- like sacculations,
gives segmented appearance to colon
cecum
location
intraperitoneal or retro?
teania coli from where?
1st part of large intestine inf to ileocecal opening location: right iliac fossa intraperitoneal but not suspended in mesentery teania coli: from appendix up continuous with ascending colon
appendix
what is it, what does it contain, where is it?
mcBurney’s joint
narrow, hollow blinded-ended tube connected to cecum
contains large aggregation of lymphoid tissue
location varies
mcBurney’s joint
1/2 from anterior superior iliac spine to umbilicus
tenderness at this point–> acute appendicitis
Ascending colon
location: right quadrants
from cecum to hepatic flexure
under right lobe of liver
retroperitoneal
Paracolic gutter
fold of peritoneum
between colon and posterolateral abdominal wall
allow passage & accumulation of fluids from different compartments of the abdomen
you can move the colon if you cut the peritoneum along the peritoneal reflection
transverse
location
intraperitoneal or retro?
longest and most movable part of colon
crosses abdomen from hepatic flexure (right hypochondrium) to splenic flexure (left hypochondrium)
completely invested by peritoneum
connected to post abdominal wall (over pancreas) by transverse mesocolon
ant. layer of mesocolon in adherent to post. layer of greater omentum
blood supply of midgut: jejunal ileal right colic middle colic marginal left colic
branches are name according to the region they are supplying
series of branches along SMA
jejunal arteries: jejunum
ileal arteries
ileocolic artery: terminal branch of SMA , ileocecal jonction
right colic artery: ascending colon
middle colic artery: midgut section of transverse colon
marginal artery: runs along mesenteric border of large intestine
connects illiocolic, right, middle from from SMA
left colic from IMA
descending colon
location:
left quadrant
from splenic flexure to sigmoid colon
splenic flexure: more acute bend, higher& more posterior than hepatic flexure
attached to diaphragm through phrenicocolic ligament.
retroperitoneal
sigmoid
location
intra or retro
S shaped portion of colon last portion of the colon left lower quadrant crosses iliac fossa to join rectum in pelvis intraperitoneal suspended in sigmoid mesocolon quite mobile since suspended in a mesocolon contain IMA
rectum
location
intraperitoneal or retroperitoneal
does not have taenia coli
from: sigmoid colon at rectosigmoid junction at S3
first portion is the extension of sigmoid colon = same diameter
rectal ampulla: dilated portion near its end, store feces before release via anal canal
anal canal as it passes through pelvic floor
ends at anorectal ring
retroperitoneal
Anal canal
terminal part of large intestine
differentiated from rectum by transition of its internal surface from endodermal to skin like ectodermal
location: below level of pelvic diaphragm
from anorectal junction to anus (external opening of recturm
surrounded by inner involuntary and outer voluntary sphincter
blood supply of the hindgut
branches are name according to region they are supplying
series of branches along inferior mesenteric artery (IMA)
left colic artery: descending colon
sigmoid arteries: sigmoid colon (in sigmoid mesocolon)
superior rectal artery: terminal branch for sup rectum
