GI embryology + basics

Question 1

esophagus, stomach, proximal duodenum

liver, gallbladder, pancreas, spleen

Answer 1

foregut

Question 2

distal duodenum → proximal 2/3 transverse colon (to splenic flexure)

Answer 2

midgut

Question 3

distal 1/3 transverse colon → sigmoid → upper rectum (to pectinate line)

Answer 3

hindgut

Question 4

foregut arterial supply

Answer 4

celiac trunk

Question 5

innervation of foregut + midgut

Answer 5

vagus nerve - parasympathetic

splanchnic nerve - sympathetic

Question 6

midgut arterial supply

Answer 6

SMA

Question 7

hindgut arterial supply

Answer 7

IMA

Question 8

innervation of hindgut

Answer 8

pelvic splanghnic nerve - parasympathetic

lumbar splanchnic nerve - sympathetic

Question 9

layers of gut wall

Answer 9

MSMS (inside to out)
Mucosa: epithelium (absorption), lamina propria (support), muscularis mucosa (motility)
Submucosa: Submucosal plexus (Meissner)
Muscularis externa: inner circular + outer longitudinal mm., Myenteric plexus (Auerbach)
Serosa: when intraperitoneal (adventitia when retroperitoneal)

Question 10

PROJECTILE VOMIT (NON-BILIOUS)
PALPABLE KNOT ("OLIVE") in pyloric region
thickening of pylorus muscularis

Answer 10

hypertrophic pyoric stenosis

Question 11

incomplete recanalization of bile duct during development of bile duct
shortly after birth:
DARK URINE
CLAY-COLORED STOOLS
JAUNDICE

Answer 11

extrahepatic biliary atresia

Question 12

abnormal fusion of ventral + dorsal pancreatic buds → forms constricting ring around duodenum → BILIOUS VOMIT (shortly after birth)

Answer 12

annular pancreas

Question 13

persisting remnant of vitelline duct → forms outpouch in ileum → ulcerations, bleeding

Answer 13

Meckel diverticulum

Question 14

mickel diverticulum presentation

Answer 14

rule of 2's:
2 inches long
2 feet from ileocecal valve
2% of population
presents within first 2 years of life
may have 2 types of epithelium: gastric, pancreatic

Question 15

normal 270° rotation is not complete → cecum and appendix in UPPER ABDOMEN
6 wk GA: midgut herniates through umbilical ring
10 wk GA: returns to abdominal cavity and rotates around SMA
associated with volvulus (twisting of intestine) → obstruction

Answer 15

malrotation of midgut

Question 16

midgut development involves rotation

Answer 16

6 wk GA: midgut herniates through umbilical ring

10 wk GA: returns to abdominal cavity and rotates around SMA

Question 17

failure of normal recanalization of lumen

present with failure to thrive

Answer 17

intestinal stenosis/atresia

Question 18

failure of neural crest cells to migrate to colon → no peristalsis
constipation
abdominal distention
no first meconium stool
BM precipitated by DRE

Answer 18

Hirschsprung Disease

Question 19

improper formation of urorectal septum, may cause:
rectovesical fistula (anus to bladder)
rectovaginal fistula
rectourethral fistula

Answer 19

anal agenesis (no anal opening)

Question 20

extruding viscera COVERED by sac (sac composed of peritoneum + amnion)
liver often found protruding
other anomalies: 50%: GI, GU, CV, CNS, MSK

Answer 20

Omphalocele = OMG its worse!

Question 21

extruding viscera NOT covered by sac
liver DOESN’T protrude
other anomalies less common: 10-15%
defect lateral to umbilicus (R>L)

Answer 21

gastroschisis

Question 22

most common tracheoesophageal anomaly

Answer 22

esophageal atresia (blind pouch) 
distal TEF (lower esophagus binds to trachea)

Question 23

watershed area of intestine:
receives blood supply from distal branches of 2 arteries (SMA + IMA)
occlusion of 1 vessel, other vessel ok → no infarction
systemic hypotension → affected first (most terminal branch of arteries)

Answer 23

splenic flexure

Question 24

branches of celiac trunk

Answer 24

L gastric artery
splenic artery
common hepatic artery

Question 25

branches of common hepatic artery

Answer 25

proper hepatic artery right gastric artery gastroduodenal artery

Question 26

branches of gastroduodenal artery

Answer 26

anterior superior pancreaticoduodenal artery | right gastroomental artery

Question 27

ligament that connects greater curvature of stomach to transverse colon

Answer 27

gastrocolic ligament

Question 28

ligament that connects greater curvature of stomach to spleen

Answer 28

gastrosplenic ligament

Question 29

ligaments cut if removing spleen (ITP, hereditary spherocytosis, trauma)

Answer 29

gastrosplenic ligament | splenorenal ligament

Question 30

ligament that connects spleen to posterior abdominal wall

Answer 30

splenorenal ligament

Question 31

ligament that connects less curvature of stomach to liver

Answer 31

gastrohepatic ligament

Question 32

access lesser sac (posterior to stomach) need to cut

Answer 32

gastrohepatic ligament

Question 33

ligament that connects connects liver to duodenum (and continuos with gastrohepatic ligament)

Answer 33

hepatoduodenal ligament

Question 34

ligament that contains portal triad (hepatic artery, common bile duct, portal vein) and can be compressed to control bleeding

Answer 34

hepatoduodenal ligament

Question 35

ligament that connects liver to anterior abdominal wall

Answer 35

falciform ligament

Question 36

GI problems associated with down syndrome

Answer 36

duodenal atresia Hirschsprung disease annular pancreas celiac disase