Lecture 4 - Embryology I

Question 1

When does folding occur?

Answer 1

4th week

Question 2

What lines the gut tube?

Answer 2

Endoderm

Question 3

What covers the gut tube?

Answer 3

Splanchnic mesoderm

Question 4

What are the foregut derivatives?

Answer 4

Oesophagus, stomach, pancreas, liver, gallbladder, proximal part of duodenum

Question 5

What are the midgut derivatives?

Answer 5

Distal part of duodenum, jejunum, ileum, caecum, ascending colon, proximal 2/3 of transverse colon

Question 6

What are the hindgut derivatives?

Answer 6

Distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, upper anal canal, internal lining of bladder and urethra

Question 7

Which structures have dual blood supply and what is their arterial supply?

Answer 7

Duodenum and pancreas

Supplied by coeliac trunk and superior mesenteric artery

Question 8

What is the peritoneal cavity?

Answer 8

Potential space containing small amount of fluid

Question 9

What is mesentery?

Answer 9

Double layer of peritoneum suspending gut tube from abdominal wall to allow conduit for blood and nerve supply and allow mobility

Question 10

How does mesentery form?

Answer 10

Condensation of splanchnic mesoderm

Question 11

What does dorsal mesentery suspend?

Answer 11

Entire gut tube from dorsal body wall

Question 12

What does ventral mesentery suspend?

Answer 12

Foregut structures

Question 13

What are the greater and lesser peritoneal sacs?

Answer 13

Dorsal and ventral mesenteries in foregut region divide the cavity into left and right sacs
Left sac = greater sac
Right sac = lesser sac

Question 14

Where is the lesser sac?

Answer 14

Behind the stomach

Question 15

What is omentum?

Answer 15

Specialised region of peritoneum

Question 16

What is the greater omentum?

Answer 16

Formed from dorsal mesentery

Question 17

What is the lesser omentum?

Answer 17

Formed from ventral mesentery, from stomach to liver

Question 18

What influences the position of the greater and lesser sacs?

Answer 18

Rotation of stomach

Question 19

When are structures retroperitoneal?

Answer 19

When they are not suspended within the abdominal cavity and never had mesentery

Question 20

When are structures secondarily retroperitoneal?

Answer 20

Began development in peritoneum, had mesentery originally but mesentery becomes lost through fusion at posterior abdominal wall

Question 21

What is proximal blind-end oesophagus?

Answer 21

Gut tube opens into respiratory tract -> fistula

Question 22

Which mesentery forms glands in the liver and biliary system?

Answer 22

Ventral

Question 23

Which mesentery forms glands in the pancreas?

Answer 23

Ventral forms uncinate process and inferior head

Dorsal forms neck down

Question 24

Which foregut structures are secondarily retroperitoneal?

Answer 24

Duodenum

Pancreas