Embyology of the foregut

Question 1

What is the embryological origin of the GIT epithelium/glands/parenchyma?

Answer 1

endoderm

Question 2

What is the embryological origin of the lamina propria, muscles, connective tissue, & other wall components in the GIT?

Answer 2

Splanchnic mesoderm

Question 3

What closes each end of the gut tube before week 4 of development?

Answer 3

Oropharyngeal membrane and Cloacal membrane

Question 4

What are the openings of the GIT called?

Answer 4

Top: Stomodeum;
Bottom: Proctodeum

Question 5

What is the blood supply to the foregut?

Answer 5

Celiac artery

Question 6

What is the sympathetic innervation of the foregut?

Answer 6

Celiac ganglia: T5-T9

Question 7

What is the parasympathetic innervation of the foregut?

Answer 7

Vagus nerve

Question 8

What divides the trachea and esophagus?

Answer 8

esophagotracheal/tracheoesophageal septum

Question 9

What is polyhydramnios?

Answer 9

Too much fluid in the amniotic sac.

May result from tracheoesophageal malformations.

Question 10

Describe the development of the stomach

Answer 10

1. Fusiform enlargement of caudal portion
2. Dorsal border is faster growing and forms the greater curvature
3. Ventral border becomes lesser curvature
4. Stomach rotates 90o (ventral moves right; dorsal moves left)

Question 11

What is the dorsal mesentery?

Answer 11

• attaches stomach to posterior wall
• called the dorsal mesogastrium
• derived from mesoderm

Question 12

What is the ventral mesentery?

Answer 12

• attaches stomach to anterior body wall
• called ventral mesogastrium
• derived from mesoderm and septum transversum

Question 13

With respect to mesentery layers, where does the liver develop and what are the mesentery layers that surround it?

Answer 13

• Liver develops between layers of ventral mesogastrium

- Divides this layer into falciform ligament (liver to body wall) and lesser omentum (GIT to liver)

Question 14

What is the free margin of the lesser omentum?

What happens to it after birth?

Answer 14

• Hepatoduodenal ligament portion of the lesser omentum.
• connects liver to the duodenum.
• contains bile duct, hepatic artery, and portal vein

Question 15

What is the omental bursa?

Answer 15

• Lesser peritoneal sac

- the space behind the stomach created during rotation of the stomach

Question 16

What connects the lesser peritoneal sac to the rest of the peritoneal cavity?

Answer 16

Epiploic foramen of Winslow

Question 17

What is congenital hypertrophic pyloric stenosis?

Answer 17

• Thickening of the pylorus
• hypertrophy of the muscular layers of the pylorus
• -> may get polyhydramnios
• -> may get projectile vomiting

Question 18

Is the duodenum intra-abdominal or retroperitoneal?

Answer 18

Yes, Secondary retroperitoneal

Question 19

Describe the development of the duodenum

Answer 19

• Grows rapidly to form a C-shaped loop.
• Epithelial cells proliferate and obliterate the lumen of the duodenum.
• Recanalization (cell death) re-opens the lumen.

Question 20

What is duodenal stenosis?

Answer 20

Partial occlusion of duodenal lumen

Question 21

What is duodenal atresia?

Answer 21

Complete occlusion of the duodenal lumen

• -> distention of epigastic region in infants –>vomiting
• -> polyhydramnios due to lack of intestinal fluid absorption

Question 22

What is a hepatic diverticulum?

Answer 22

“liver bud” ie. gives rise to upper (liver) and lower (gallbladder & biliary tree) divisions
- vental outgrowth from the caudal part of the foregut

Question 23

Kupfer cells and hematopoietic tissue of the liver are derived from what?

Answer 23

mesenchyme in the septum transversum

Question 24

What is the blood supply of the liver?

Answer 24

hepatic artery (branch of celiac artery)

Question 25

What do the cystic duct and common bile duct develop from?

Answer 25

stalk of the liver bud (hepatic diverticulum)

Question 26

What is the portal triad?

Answer 26

Hepatic portal vein, hepatic artery, common bile ducts.

Question 27

Where is the portal triad?

Answer 27

Hepatoduodenal ligament (from ventral mesentery)

Question 28

What makes up the ventral mesentery?

Answer 28

- lesser omentum - falciform ligament - round ligament of liver (umbilical vein)

Question 29

What makes up the lesser omentum?

Answer 29

- hepatoduodenal ligament | - hepatogastric ligament

Question 30

What is extrahepatic biliary atresia

Answer 30

- Failure of recanalization | - -> duplication of gallbladder

Question 31

What is the sphincter of Oddi?

Answer 31

Sphincter in major duodenal papilla

Question 32

What forms the main pancreatic duct?

Answer 32

Distal part of dorsal pancreatic duct & duct of ventral pancreas

Question 33

What forms the accessory pancreatic duct?

Answer 33

Proximal part of dorsal pancreatic duct

Question 34

Most of the pancreas is derived from what?

Answer 34

Dorsal pancreatic bud (from caudal portion of the foregut)

Question 35

Name a couple pancreatic malformations

Answer 35

``` Annular pancreas (fails to correct rotation) Accessory pancreatic tissue in other structures (stomach, duodenum, or ileal diverticulum) ```

Question 36

What is the spleen derived from?

Answer 36

Mass of mesenchymal cells in dorsal mesogastrium

Question 37

What is the sympathetic innervation of the spleen?

Answer 37

T5-T9

Question 38

What is the parasympathetic innervation of the spleen?

Answer 38

Vagus nerve