GI embryology (334-335)

Question 1

what adult structures does the foregut form

Answer 1

pharynx to duodenum

Question 2

what adult structures does the midgut form

Answer 2

duodenum to proximal 2/3 of transverse colon

Question 3

what adult structures does the hindgut form

Answer 3

distal 1/3 of transverse colon to anal canal above pectinate line (proximal 2/3 of anal canal)

Question 4

what kind of developmental folding defects lead to anterior abdominal wall defects

Answer 4

failure of rostral fold closure: sternal defects

failure of lateral fold closure: omphalocele, gastroschisis

failure of caudal fold closure: bladder exstrophy

Question 5

what is duodenal atresia and what genetic defect is it associated with

Answer 5

failure to recanalize the duodenum leading to missing or closed portions of the duodenum

associated with trisomy 21

Question 6

what causes jejunal, ileal and colonic atresia

what characteristic shape does the bowel take as a result

Answer 6

vascular accident

bowel is spiral shaped like an “apple peel”

Question 7

what happens to the midgut at the 6th week of development; what happens at the 10th week

Answer 7

at the 6th week the midgut herniates through the umbilical ring

at the 10th week the midgut is completely reduced and it rotates around the SMA

Question 8

name three tracheoesophageal anomalies

Answer 8

esophageal atresia,
tracheoesophageal fistula,
esophageal atresia with tracheoesophageal fistula

Question 9

which tracheoesophageal anomaly is most common

Answer 9

esophageal atresia with distal tracheoesophgeal fistula (85% of cases)

Question 10

what clinical exam findings and x-ray findings suggest a tracheoesophageal anomaly

Answer 10

clinical Sx: choking, drooling and vomiting with first feeding
also, cyanosis occurs secondary to laryngospasm (to avoid reflux-related aspiration)

x-ray will show air in the stomach for TEF

Question 11

what clinical test would be used to determine if there is a tracheoesophageal anomaly

Answer 11

test: try to pass an NG tube into the stomach

failure to be able to do so is evidence of tracheoesophageal anomaly

Question 12

what causes congenital pyloric stenosis

Answer 12

hypertrophy of the pylorus

Question 13

what on history and physical exam would be indicative of congenital pyloric stenosis

Answer 13

• palpable “olive-like” mass in the epigastric area

- non-bilious projectile vomiting at 2-6 weeks old

Question 14

how is congenital pyloric stenosis treated

Answer 14

surgical incision

Question 15

in what demographic are more cases of congenital pyloric stenosis found

Answer 15

firstborn males

Question 16

what is the embryologic origin of the pancreas

Answer 16

foregut

Question 17

which part of the pancreas is formed by the ventral pancreatic bud

Answer 17

the uncinate process

Question 18

what parts of the pancreas are formed from the dorsal pancreatic bud

Answer 18

the body, tail, isthmus and accessory pancreatic duct

Question 19

define annular pancreas

Answer 19

a condition in which a ring of pancreatic tissue remains encircling the duodenum where the ventral pancreatic bud had once moved around the duodenum from right to left;
annular pancreas may cause duodenal narrowing

Question 20

define pancreas divisum

Answer 20

the ventral and dorsal parts of the pancreas fail to fuse at 8 weeks

Question 21

how is the embryologic origin of the spleen different from that of the esophagus, stomach and intestines

Answer 21

the spleen derives from the mesoderm

Question 22

blood supply to the spleen is the same as that of which embryologic section of the GI tract (foregut, midgut, hindgut)

Answer 22

foregut;

the spleen is supplied by the celiac artery

Question 23

what is the incidence of congenital pyloric stenosis

Answer 23

1/600 live births