Midgut- Hindgut

Question 1

Mindgut
why is it different from the rest of GI tract
blood supply?

Answer 1

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)

Question 2

Hindgut
why is it different from the rest of GI tract
blood supply

Answer 2

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)

Question 3

Duodenum: location
gerneral
intraperitoneal or retroperitoneal

Answer 3

midgut
C-shaped
around head of pancreas
located above umbilicus 
retroperitoneal, except for its 1st portion

Question 4

Duodenum: 4 parts anatomy

Answer 4

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

Question 5

Duodenum: arterial supply

Answer 5

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

Question 6

Jejunum
function
location
from where to where

Answer 6

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

Question 7

jejunum:

anatomy

Answer 7

plicae circulares: numerous circular folds in its lumen (increase surface area for absorption)
arterial supply distribution: less prominent arterial arcades and long vasa recta

Question 8

ileum
general
location

Answer 8

final section of the small intestine
make distal 3/5 of small intestine
longer than jejunum

Question 9

ileum:

anatomical distinction

Answer 9

contains lymphoid nodules (Peyer’s patches)
plicae circulares: low & sparse
denser arterial arcades & shorter vasa recta

Question 10

mesentery of small intestine

Answer 10

ileum & jejunum are suspended in mesentery

peritoneal fold that carries blood vessels, lymphatics & nerve fibers

Question 11

small intestine: arterial supply

Answer 11

from SMA
giving jejunal& ileal arteries
ending in arterial arcades & vasa recta

Question 12

meckel’s diverticulum

Answer 12

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

Question 13

large intestine: overal location

Answer 13

1.5m long
extends from cecum to anal canal
converts liquid feces to semisolid state
absorb water, salt& electrolytes

Question 14

large intestine:

composed of?

Answer 14

midgut: 
Cecum
appendix 
colon: ascending, 1/2 of transverse 
hindgut: 
colon (1/2 transverse, descending, sigmoid) 
rectum
anal canal

Question 15

large intestine:

characteristics

Answer 15

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

Question 16

cecum
location
intraperitoneal or retro?
teania coli from where?

Answer 16

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

Question 17

appendix
what is it, what does it contain, where is it?
mcBurney’s joint

Answer 17

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

Question 18

Ascending colon

Answer 18

location: right quadrants
from cecum to hepatic flexure
under right lobe of liver
retroperitoneal

Question 19

Paracolic gutter

Answer 19

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

Question 20

transverse
location
intraperitoneal or retro?

Answer 20

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

Question 21

blood supply of midgut:
jejunal 
ileal
right colic 
middle colic
marginal
left colic

Answer 21

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

Question 22

descending colon

Answer 22

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

Question 23

sigmoid
location
intra or retro

Answer 23

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

Question 24

rectum
location
intraperitoneal or retroperitoneal

Answer 24

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

Question 25

Anal canal

Answer 25

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

Question 26

blood supply of the hindgut

Answer 26

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