GI - Embryology

Question 1

What part of GI tract makes up the foregut?

Answer 1

Foregut - pharynx to duodenum

Question 2

What part of GI tract makes up the midgut?

Answer 2

Midgut - duodenum to proximal 2/3 of transverse colon

Question 3

What part of GI tract makes up the hindgut?

Answer 3

Hindgut - distal 1/3 of transverse colon to anal canal above pectinate line

Question 4

What are the 3 types of failure that cause developmental defects of anterior abdominal wall?

Answer 4

Development defects of anterior abdominal wall due to failure of: (1) Rostral fold closure: sternal defects (2) Lateral fold closure: omphalocele, gastroschisis (3) Caudal fold closure: bladder exstrophy.

Question 5

What is an example of an anterior abdominal wall defect due to failure of rostral fold closure?

Answer 5

Rostral fold closure: sternal defects

Question 6

What are 2 examples of an anterior abdominal wall defect due to failure of lateral fold closure?

Answer 6

Lateral fold closure: (1) omphalocele, (2) gastroschisis

Question 7

What is an example of an anterior abdominal wall defect due to failure of caudal fold closure?

Answer 7

Caudal fold closure: bladder exstrophy

Question 8

What causes duodenal atresia?

Answer 8

Duodenal atresia - failure to recanalize (trisomy 21)

Question 9

What causes jejunal atresia? What other types of atresia does this cause? What is their collective nickname?

Answer 9

Jejunal, ileal, colonic atresia - due to vascular accident (apple peel atresia)

Question 10

What occurs during the 6th week of midgut development?

Answer 10

Midgut development: 6th week - midgut herniates through umbilical ring

Question 11

What occurs during the 10th week of midgut development?

Answer 11

Midgut development: 10th week - returns to abdominal cavity + rotates around SMA

Question 12

What are 4 types of pathology associated with GI embryology?

Answer 12

Pathology - (1) Malrotation of midgut (2) Omphalocele (3) Intestinal atresia or stenosis (4) Volvulus

Question 13

What is Gastroschisis? How is it different from Omphalocele?

Answer 13

Gastroschisis - extrusion of abdominal contents through abdominal folds; not covered by peritoneum

Question 14

What is Omphalocele? How is it different from Gastroschisis?

Answer 14

Omphalocele - Persistence of herniation of abdominal contents into umbilical cord, sealed by peritoneum; Think: “ompahloCELE SEALed by peritoneum”

Question 15

What is the most common tracheoesophageal anomaly? Give the associated percentage.

Answer 15

Esophageal atresia (EA) with distal tracheoesophageal fistual (TEF) is the most common (85%)

Question 16

What symptoms result from tracheoesophageal anomalies (specifically EA with TEF), and in what context?

Answer 16

Results in drooling, choking, and vomiting with first feeding

Question 17

What is a CXR finding associated with TEF, and what causes this?

Answer 17

TEF allows air to enter stomach (visible on CXR).

Question 18

What causes cyanosis in the context of EA with TEF? What is the purpose of this mechanism?

Answer 18

Cyanosis is secondary to laryngospasm (to avoid reflux-related aspiration).

Question 19

What is the clinical test for EA with TEF?

Answer 19

Clinical test: failure to pass nasogastric tube into stomach

Question 20

Define Pure TEF (H-type).

Answer 20

In H-type it is a fistula alone

Question 21

What does a CXR show in pure atresia (isolated) EA?

Answer 21

In pure atresia (isolated) EA the CXR shows gasless abdomen.

Question 22

Draw the trachea and esophagus for each of the following contexts: (1) Normal anatomy (2) Pure EA (atresia or stenosis) (3) Pure TEF (H-type) (4) EA with distal TEF (most common).

Answer 22

See p. 334 in First Aid 2014 for figure at bottom of page

Question 23

What occurs in Congenital pyloric stenosis?

Answer 23

Hypertrophy of the pylorus causes obstruction.

Question 24

What physical sign characterizes Congenital pyloric stenosis? What symptom presents, and when?

Answer 24

Palpable “olive” mass in epigastric region and nonbilious projectile vomiting at ~ 2-6 weeks old

Question 25

What is the treatment for Congenital pyloric stenosis?

Answer 25

Treatment is surgical incision

Question 26

In what proportion of Congenital pyloric stenosis does Congenital pyloric stenosis occur? In what patient population is it more often?

Answer 26

Occurs in 1/600 live births, more often in firstborn males

Question 27

What is the embryological origin of the Pancreas?

Answer 27

Pancreas - derived from foregut

Question 28

To what 3 structures does the ventral pancreatic bud contribute?

Answer 28

Ventral pancreatic buds contribute to the pancreatic head and main pancreatic duct; The uncinate process is formed by the ventral bud alone

Question 29

What forms the ucinate process?

Answer 29

The uncinate process is formed by the ventral bud alone

Question 30

What does the dorsal pancreatic bud become? Specify the 4 main structures.

Answer 30

The dorsal pancreatic bud becomes everything else (body, tail, isthmus, and accessory pancreatic duct).

Question 31

What defect causes an annular pancreas, and what results?

Answer 31

Annular pancreas - Ventral pancreatic bud abnormally encircles 2nd part of duodenum; forms a ring of pancreatic tissue that may cause duodenal narrowing

Question 32

What causes Pancreas divisum?

Answer 32

Pancreas divisum - ventral and dorsal parts fail to fuse at 8 weeks

Question 33

What is the embryological origin and arterial supply of the spleen?

Answer 33

Spleen - arises in mesentery of stomach (hence is mesodermal) but is supplied by foregut (celiac artery)

Question 34

Draw and label a visual including the following structures: (1) Accessory pancreatic duct (2) Dorsal pancreatic bud (3) Main pancreatic duct (4) Major papilla (5) Minor papilla (6) Gallbladder (7) Pancreatic duct (8) Uncinate process (9) Ventral pancreatic bud.

Answer 34

See p. 335 in First Aid 2014 for visual