Embryology

Question 1

What develops from the foregut?

Answer 1

esophagus, stomach, ⅓ of duodenum, liver, gallbladder, biliary ducts, pancreas

Question 2

What develops from the midgut?

Answer 2

⅔ of duodenum, jejunum, ileum, cecum, appendix, ascending colon, ⅔ trans colon

Question 3

What develops from the hindgut?

Answer 3

⅓ trans colon, descending colon, sigmoid colon, rectum, proximal anal canal

Question 4

What develops from the dorsal mesentery?

Answer 4

greater omentum, gastrospenic lig, gastrocolic lig, gastrophrenic lig, splenorenal lig, mesocolon, “the mesentery”

Question 5

What develops from the ventral mesentery?

Answer 5

hepatogastric lig, hepatoduodenal lig, falciform lig, coronary lig

Question 6

What is different between where the dorsal and ventral mesenteries are found?

Answer 6

ventral mesentery only in abdominal foregut

Question 7

Where is the hepatic diverticulum?

Answer 7

ventral mesentery

Question 8

What does the hepatic diverticulum form?

Answer 8

liver, gallbladder, dorsal pancreatic bud

Question 9

What is an annular pancreas?

Answer 9

ventral pancreas is around duodenum; bad only when inflamed

Question 10

How does the spleen form?

Answer 10

spleen forms by aggregation of epithelial and hematopoietic cells within dorsal mesentery

Question 11

What causes duodenal stenosis? pyloric stenosis?

Answer 11

• duodenal stenosis: failure to recanalize duodenum → bilious vomit
• pyloric stenosis: hypertrophy of pyloric muscle

Question 12

What is Meckel’s Diverticulum?

Answer 12

partial persistence of the omphalomesenteric duct with proximal patency
common: 2-3% of pop
most commonly 2 ft from ileocecal valve on anti-mesenteric border
30-50% contain gastric mucosa capable of making acid and gastric enzymes
clinical:
rectal bleeding,
vomiting-bowl obstruction,, acute abdominal pain

Question 13

What is “pyloric stenosis”? What will you see?

Answer 13

post-natal “developmental defect” w/ hypertrophy and hyperplasia of muscle layers
clinical:
3-12 wk onset
non-bilious, projectile emesis
weight loss
hyperperistaltic waves
palpable “pyloric olive”
hypoCl-, K-
metabolic alkalosis

Question 14

What is duodenal atresia/stenosis and what do you see?

Answer 14

early embryologic defects so see other anomalies: 30% Down Syndrome
complete (atresia) or incomplete (stenosis, web, diaphragm) obstruction
80% distal to ampulla of vatar → bilious vomiting
AXR: “double bubble sign” - gastric and duodenal w/ absent distal gas

Question 15

What is Malrotation and Midgut Volvulus - and what do you see/do?

Answer 15

failure of normal rotation of intestine → arrest of cecum in abnormal site with formation of adhesions Ladd’s Bands to posterior peritoneal wall → obstruction
symps: bilious emesis, rectal bleeding
if small bowel occlude SMA → EMERGENCY ischemic necrosis
major cause of short bowel

Question 16

What do you seen in intestinal obstruction in newborn ? Upper vs lower?

Answer 16

inc intraluminal P → decreased venous and arterial blood flow
if untreated can lead to necrosis, perforation, peritonitis
complete: early symps (24-48 hrs)
incomplete: variable
history: polyhydramnios, toxemia, bleeding, viral infection diabetes, CF
symps: bilious vomit, distension, delayed/absent meconium passage, increased gastric aspirate (>15 ml)
upper part: early onset, decreased distal
lower: after 24 hrs age, multiple air-filled loops of bowel; “micro colon” on barium enema