GI Embryology

Question 1

What is peritoneal reflection?

Answer 1

Change in direction

Question 2

What classifies a structure as retro peritoneal?

Answer 2

Never in the peritoneal cavity and no mesentery

E.g aorta, kidneys , vena cava

Question 3

What classifies as structure as secondary retro peritoneal?

Answer 3

Begin development in the peritoneum had a mesentery but with growth this is lost through fusion at posterior abdominal wall.
E.g asc and desc colon and duodenum.

Question 4

What is fusion fascia?

Answer 4

Peritoneum of posterior abdominal wall is squished together with the duodenum and mesentery growing over it. It is Avascular

Question 5

When Does the respiratory diverticulum develop and from what?

Answer 5

4th week

Grows off the ventral wall of the foregut

Question 6

What divides the respiratory primordium ventrally and the oesophagus dorsally?

Answer 6

Tracheoesophageal septum

Question 7

What foregut structures are formed in the ventral mesentery?

Answer 7

Liver, biliary system and part of the pancreas

Question 8

What FG structures are formed in the dorsal mesentery?

Answer 8

Rest of pancreas

Question 9

What does the liver develop from?

Answer 9

The hepatic bud

Question 10

What happens to the duodenum in weeks 5 and 6?

Answer 10

Lumen is obliterated due to lining growing so quickly

Question 11

What lines the primitive gut tube?

Answer 11

Endoderm

Question 12

What are the 3 sections of the primitive gut tube?

Answer 12

Foregut, midgut and hind gut

Question 13

What week of development does the primitive gut tube begin in?

Answer 13

3rd

Question 14

Where does the primitive gut tube run from and to?

Answer 14

Starts at the stomatodeum runs rostrally to the proctodeum caudally with an opening at the umbilicus

Question 15

What is the opening of the primitive gut tube to the yolk sac called?

Answer 15

The vitelline duct

Question 16

What are the two types of mesoderm surrounding the gut called and what do they become?

Answer 16

Somatic mesoderm - becomes muscles and fascia of the abdominal wall.
Splanchic mesoderm develops into smooth muscle of the gut wall

Question 17

What is the space created by the split in mesoderm called?

Answer 17

Coelomic cavity (forerunner of the pleural cavity and peritoneal cavity)

Question 18

What is the point where the two sides of the abdominal wall meet in lateral folding?

Answer 18

Linea alba

Question 19

What are the 3 layers of muscle found In The anterolateral abdominal wall?

Answer 19

External oblique, internal oblique and transverse abdominis

Question 20

What is the inguinal canal?

Answer 20

An oblique passageway through the layers of abdominal wall allowing the passage of the developing testis into the scrotum

Question 21

What is an umbilical hernia?

Answer 21

A congenital abnormality where the intestines protrude through the abdominal wall via the umbilicus

Question 22

What divides the intraembryonic coelom to become what?

Answer 22

The diaphragm divides it into the abdominal and the thoracic cavity

Question 23

What is the peritoneum?

Answer 23

The serous membrane that forms the lining of the abdominal cavity

Question 24

What attaches the entire developing gut to the roof of the abdominal cavity?

Answer 24

The dorsal mesentery

Question 25

What holds the foregut only to the floor of the abdominal cavity?

Answer 25

Ventral Mesentery

Question 26

What is a mesentery?

Answer 26

A fold in the mesoderm allowing passage to vessels and nerves in adults

Question 27

What are the adult derivatives of the foregut?

Answer 27

Oesophagus, stomach, pancreas, liver, gall bladder and duodenum (proximal to the bile duct)

Question 28

What are the adult derivatives of the mid gut?

Answer 28

Duodenum (distal to bile duct) , jejunum, ileum, cecum, ascending colon and proximal 2/3 of the transverse colon

Question 29

What are the adult derivatives of the hind gut?

Answer 29

Distal 3rd of the transverse colon, descending colon, sigmoid , rectum , upper anal canal, internal lining of bladder and urethra

Question 30

What defines a Retroperitoneal structures?

Answer 30

Organs/structures that were never in the peritoneal cavity and never had a mesentery e,g aorta, kidneys, vena cava