Digestive System

Question 1

List the structures of the GI tract in order starting with the stomach

Answer 1

Stomach, Duodenum, Jejunum, Ileum, Cecum, Ascending colon, Transverse colon, Descending colon, Sigmoid colon, Rectum, Anus

Question 2

What are the three developmental sections of the GI tract?

Answer 2

Foregut, Midgut, Hindgut

Question 3

Name the vessel off the aorta for each embryonic GI section

Answer 3

Foregut - Celiac trunk, Midgut - Superior mesenteric artery, Hindgut - Inferior mesenteric artery

Question 4

What is the farthest structure into the GI tract which is innervated by the vagus nerve?

Answer 4

The distal portion of the transverse colon

Question 5

From what embryonic GI structure is the duodenum derived?

Answer 5

Foregut and midgut

Question 6

What is the arterial supply of the duodenum?

Answer 6

Celiac and superior mesenteric arteries

Question 7

Does the duodenum occupy an intraperitoneal or retroperitoneal position?

Answer 7

Both. The 1st portion is intraperitoneal, the 2nd through 4th portions are retroperitoneal

Question 8

Where are the dorsal and ventral pancreatic ducts when they fuse?

Answer 8

At the foregut-midgut junction

Question 9

When the dorsal pancreatic duct persists what is it called?

Answer 9

The accessory pancreatic duct

Question 10

What is an annular pancreas, what causes it, and what might it cause?

Answer 10

When the dorsal and ventral pancreas buds dont properly fuse. It can happen when the two buds migrate opposite directions, and it can cause duodenal stensosis (ventral pancreas sits right on duodenum)

Question 11

What happens to the duodenal lumen during development?

Answer 11

It is obliterated in the 5th or 6th week and recanalized by the end of the 8th week

Question 12

What is the difference between duodenal stenosis and duodenal atresia

Answer 12

Stenosis is a partial occlusion, atresia is a complete occlusion

Question 13

Where are duodenal stenosis and duodenal atresia respectively most common?

Answer 13

Stenosis - 3rd and 4th portions of duodenum, Atresia - 2nd or 3rd portion of duodenum

Question 14

Why is polyhydramnios present with duodenal atresia?

Answer 14

Because the embryo normally swallows amniotic fluid, but cannot if the duodenum is completely occluded

Question 15

What do we typically look for when checking for possible duodenal atresia?

Answer 15

A double bubble appearence on ultrasound. Air will be present in both stomach and duodenum.

Question 16

Invasion of the caudal portion of the septum transversum by the liver bud creates what structure?

Answer 16

The ventral mesentery

Question 17

What are the derivatives of the ventral mesentery?

Answer 17

Falciform ligament, lesser omentum (divided into hepatogastric ligament to left and hepatoduodenal ligament to right)

Question 18

What are the derivatives of the midgut?

Answer 18

Duodenum (some of 2nd portion, all of 3rd and 4th portion), Jejunum, Ileum, Cecum, Appendix, Ascending Colon, Two thirds of Transverse colon

Question 19

When does umbilical herniation start and when does it return?

Answer 19

6th week to 10th week

Question 20

Omphalocele

Answer 20

An abdominal wall defect in which the intestines, liver, and occasionally other organs remain outside abdomen

Question 21

Gastroschisis

Answer 21

Congenital abdominal wall defect in which the intestines and sometimes other organs develop outside the fetal abdomen through an opening in the abdominal wall

Question 22

Midgut rotations

Answer 22

A 90 degree CCW rotation while in cord around axis of SMA, and a 180 degree CCW rotation during reduction of hernia

Question 23

Are each of the following fused or mobile, ascending colon, descending colon, transverse colon

Answer 23

Ascending and Descending are fused (to pos abdominal wall), Transverse has some mobility (fuses with pos wall of greater omentum)

Question 24

Volvulus

Answer 24

A twisted intestine, may compromise blood supply

Question 25

Left sided colon

Answer 25

When the gut rotates 90 degrees cw instead of ccw during development

Question 26

What most likely causes gut atresias and stenoses

Answer 26

Vascular accidents

Question 27

Meckels (Ileal) Diverticulum

Answer 27

Failure of vitelline duct to degenerate completely (can cause ulceration, bleeding, perforation)

Question 28

What separates the allantois and hindgut?

Answer 28

Urorectal septum

Question 29

What are the two divisions of the cloacal chamber?

Answer 29

Rectum and urogenital sinus

Question 30

What are four conditions that may arise from abnormal hindgut development?

Answer 30

Persistent cloaca, anal stenosis, fistulas of various types, rectal atresia

Question 31

Two types of hindgut fistulas

Answer 31

Urorectal fistula (connects distal hindgut to urinary system) and Rectovaginal fistula (connects rectum to vagina)

Question 32

What might be one cause of rectal stenosis

Answer 32

Failure of neural crest cells to migrate and bring innervation to distal hindgut (no innervation will cause stenosis). This situation can cause congenital megacolon (Hirschsprung disease)

Question 33

What is the primary concern regarding malrotation of the gut during physiologic herniation?

Answer 33

A malrotation may lead to a kinked superior mesentary artery

Question 34

What is a quick way to recognize a malrotation of gut herniation?

Answer 34

A transverse colon behind the duodenum (normally the transverse colon will be anterior to the duodenum)