midgut and hindgut Flashcards
where does the foregut range from?
From esophagus to D3/D4 segment of the duodenum
where does the midgut range from?
D4 Segment (transition portion), Jejunum, ileum, cecum, ascending and first 2/3 of the transverse colon
where does the hindgut range from?
Distal 1/3 transverse colon, descending colon, sigmoid colon, rectum
how long is the SI?
6-7m
how long is the duodenum?
20-25 cm
what type of organs are the ileum and jejunum?
intraperitoneal organ
what suspends the ileum and jejunum to the posterior abdominal wall?
mesentery proper
what travels within the mesentery proper?
vessels
what is prominently found in the jejunum which is not as prominent even absent in the ileum? what is its function?
plicae circulares
function; increases surface area and allows for maximal absorption
how could the wall of the jejeunum be described?
thicker and more red in color
how can the vessels of the jejunum be described as?
- long vasa recta vessels (straight)
- few vascular arcades (loops)
where is the jejunum located anatomically
in the LUQ
how can the wall of the ileum be described as?
thinner, whiter in color due to less vessels
how could the vessels of the ileum be described?
short vasa recta
many large vascular arcades
what is present exclusively in the ileum and served to filter fluids?
Peyer’s patch which are lymphatic aggregates
where is the ileum located anatomically?
RLQ
how long is the colon
~1.5m
where does the colon range from
ileocecal junction to the anus
how does the ileocecal valve differ from other sphincters?
Ileocecal valve uses pressure differentials as opposed to actual motor activity like most sphincters
what part of the colon is jointed to the left by the ileum?
cecum
what is the cecum?
Blind-ended pouch located in the lower right quadrant
what is contained in the cecum of the colon that serves as an extension?
appendix
what is the appendix?
narrow blind ended tube
what type of organ is the appendix?
intraperitoneal
if we refer to the appendix being found post-ileal what does it mean?
behind the ileum
if we refer to the appendix being found retroceccal what does it mean?
behind cecum
if we refer to the appendix being found subcecal what does it mean?
under the cecum
if we refer to the appendix being found in the pelvic what does it mean?
pointing towards the pelvis
if we refer to the appendix being found pre/sub-ileal what does it mean?
infront of the ileum
where is the appendix located?
at McBurnery’s point
measures from the Right ASIS to the umbilicus, at the lateral 1/3
what type of organ is the ascending colon?
retroperitoneal organ
where does the ascending colon extend from?
Extends superiorly from the cecum to the liver
where does the acending colon transition into the transverse colon?
at the hepatic flexure
what type of organ is the transverse colon?
intraperitoneal organ
where does the transverse colon extend from?
ascending colon at hepatic flexure to the descending colon at the splenic flexure
relative to the hepatic flexure where is the splenic flexure?
higher up, due to big size of the liver
what suspends the transverse colon?
by transverse mesocolon
what can the transverse mesocolon be easily confused with in the lab?
with the greater omentum
what type of organ is the descending colon?
retroperitoneal organ
where does the descending colon extend from?
Extends down from the splenic flexure and distally will continue as the sigmoid colon
what type of organ is the sigmoid colon?
intraperitoneal organ
how is the sigmoid colon shaped?
Forms S shaped loop
where does the sigmoid colon extend from?
ends at the sacrum and continues to the rectum
what suspends the sigmoid colon?
fan-shaped sigmoid mesocolon
what is the final portion of the colon?
rectum and anal canal
how could the lumen of the colon be described as?
large
what is teniae coli of the colon?
3 thickened binds of longitudinal muscles
what does the teniae coli create?
folds onto itself such as ruching in dresses
what is the function of the haustra?
Out-pockets to have fecal matter clumping together in order to better absorb H20 and Ions
what are epiploic appendages?
Fatty tags enclosed by peritoneum attached in rows along teniae coli
what is the function of the epiploic appendages?
Provide proprioception for the colon
What A gives blood to the midgut?
superior mesenteric A
what gives blood to the hind gut?
Inferior mesenteric A
at what level can the SMA be identified?
L1
at what level can the IMA be identified?
L3
where does the SMV sit and where does the SMA sit?
vein sits on the right near IVC
artery sits on the left near aorta
how does the SMA travel?
Comes off of the aorta and travels posterior to the D1 segment and the neck of the pancreas
what is created by the jejunal and ileal branches of the SMA?
Creates the vascular arcades that go towards jejunum and ileum
how do the ileal and jejunal branches travel? think of the drawing
travel on the left side of the loop of the SMA
what are the main braches that comes from the right of the SMA?
inferior pancreaticoduodenal A (anterior and posterior)
ileocolic A
right colic A
middle colic A
where does the ileocolic A travel?
• Towards the cecum and ileum also close to the appendix
the appendicular A is a branch of what A?
ileocolic A
where does the right colic A travel to?
ascending colon
where does the middle colic A travel to?
to the transverse colon, it comes up and will curl around the hepatic flexure
does the IMA have a partnering vein?
no
what branches arise from the IMA?
left colic A
sigmoidal aa
superior rectal A
where does the left colic A travel to?
to the descending colon
what joins with the left colic A to form the marginal A?
the middle colic A
what aa supply the sigmoid portion of the colon?
sigmoidal aa
what gets blood from the superior rectal A?
rectum and upper anal canal
what is the marginal A of drummond important for?
providing blood supply in cases of blocks
what is known as the watershed area?
splenic flexure
what is the watershed area?
area of dual blood supply
