G22 Midgut Hindgut

Question 1

Midgut and hindgut anatomy

Answer 1

duodenum, jejunum, ileum, cecum, acs and 2/3 trans colon
-digest and absorb

hind
transverse colon, descending and sigmoid colon, rectum
resorb fluid and electrolytes

Question 2

midgut and hindgut blood supply/innervation and lymph

Answer 2

Mid: superior mesenteric artery

• sympathetics: superior mesenteric ganglion
• parasympatheticL Vagus
• lymphatics: superior mesenteric nodes

Hindgut: inferior mesenteric artery
sympathetics: multiple
parasympatheticsL pelvic splanchnic nerves
lymphatics: inferior mesenteric nodes

Question 3

duodenum peritoneum and flexures

Answer 3

L1 1st part, intraperitoneal (foregut)
-C-cap (ampula) no circular folds

L1-L3: second retroperitoneal (descending)
L3 third -retroperitoneal - horizontal
L3-L2 fourth- retroperitoneal- ascending

Duodenojejunal flexure: transition from retroperitoneal to intraperitoneal
-duodenal fossa

susupensory muscle of duodenum: ligament of trietz (attachment to the right crus of esophagus through diaphragm)

plicae circularis

Question 4

Jejunum and Ileum

Answer 4

6-7m long, intraperitoneal, infracolic compartment

Plicae circularis- circular folds, do not distend
-jejunum (MOST), proximal ileum, some, distal ileum only some folds

arcade: loops of arteries in mesentary
vasa recta: extentions from the loop that touch the intestine

Jejunum: single or double arcades with LONG vasa recta
-thick, lareg diameter, less mesenteric fat, tight large plicae circularis, lymphoid peyers patches few

Ileum: multiple arcades, short vasa recta, peyers patches visible on epithelium
-thisn, mall diameter, more mesenteric fat, few plicae circularis, peyers patches lymph.

Question 5

Ileal Diverticulum

Answer 5

2% fo people

remnant of vitelline duct (from yolk sac to dev gut)

antimesenteric border of ileum
60cm proximal to ileocecal valve

true diverticulum because it contains ALL layers of intestinal wall

ulceration mucosa can lead to pain, bleeding and perforation

inflammation will produce pain referred to umb region

Question 6

Large intestine

Answer 6

ileocecal valve

cecum: end intraperitoneal
- ileocecal lips “ileal papilla”

Omental appendicies: fatty projections of omentum attached to LI

Tenia ColiL three smooth muscle bands, converge at appendix.
Haustra- sacculations (name on inside)
-semilunar folds on inside-segment and control size of fecal mass

ascending colon: right paracolic gutter
right colic (hepatic flexure)
transverse colon (intraperitoneal and transverse mesocolon)
(midgut/hindgut barrier)
left coloc (splenic) flexure
descending colon (left paracolic gutter) (retro)
sigmoid colon (sigmoid mesocolon) (intra)
rectosigmoidal junction (no more tenia coli)\
rectum

problems: 11% ascending mesocolon (no longer retroperitoneal), mobile cecum can lead to volvulus (twist/block)

Question 7

appendix

Answer 7

appendix (orifice of appendix)

• mesoappendix (with appendicular artery) (ligated with appendectomy)
• retrocecal recess
• can be fixed retrocecal appendix
• McBurneys POINT: on spinoumbilical line???
• APPENDICITIS: refers periumbilical (visceral pain refers dull and burning to body wall, if it goes from dull poorly localized to well localized sharp pain, indication of different problem: inflamed appendix is now in contact with parietal peritoneum of abdominal wall, branches of anterior rami of sensory inntervation, sending localized somatic sensory pain back); sever localized pain in RLQ when parietal peritoneum is irritated

Question 8

Hirschsprungs Disease

Answer 8

congenital aganglionic megacolon

congenital disorder of colon in which NC did not micrate during development to form enteric nervous system

chronic constipation and enterocolitis
inflammation of small intestine.

Question 9

referred pain of the viscera

Answer 9

foregut: epigastric
midgut: umbilical
hindgut: hypogastric

Question 10

Superior mesenteric artery

Answer 10

unpaired branch of abdominal aorta

L1 posterior to the panc

crosses the Left renal vein anteriorly

crosses 3rd part of duodenum ANTERIORLY

crosses ANTERIOR to uncinate process of pancreas

Question 11

anastomosis of SMA and Celiac trunk flow

Answer 11

pancreaticduodenul artery drops off common hepatic artery from celiac trunk
-arcades travel along duodenum and uncinate process of panc

inferior pancreaticoduodenal artery directly off superior mesenteric artery and reached up along uncinate process.

THESE TWO ANASTIMOSE

Question 12

branches of superior mesenteric artery

Answer 12

15-20 jejunal and ileal branches

anastomosing arcades

vasa recta (long)

NAMED BRANCHES

right colic –goes to ascending colon
ileocolic: ileum, cecum, asc colon, appendicular
middle colic: transverse colon
marginalL anastomosing loop around colon

Question 13

Inferior Mesenteric Artery:

Answer 13

lower left off the aorta

unpaired branch of abdominal aorta

branches AT L3

NAMED BRANCHES

Left Colic: tranverse and descending colon
3-4 sigmoid branches
-arcades and vasa recta
superior rectal (last of IMA)

Question 14

portal vein

Answer 14

splenic vein
inferior mesenteric vein
superior mesenteric vein: thick

(small gastric branches)

Question 15

lymphatic drainage

Answer 15

superior mesenteric nodes

inferior mesenteric and lumbar nodes