Week 2 - Development Of The Peritoneum And Foregut

Question 1

How do we get a ventral body wall and a gut within a cavity?

Answer 1

Embryonic folding

Question 2

In the 4th week when the embryo folds laterally, what does this create?

Answer 2

Ventral body wall, primitive gut becomes tubular

Question 3

In the 4th week when the embryo folds craniocaudally, what does this create?

Answer 3

Cranial and caudal pockets from yolk sac endoderm

Question 4

Describe the embryonic divisions of the gut?

Answer 4

Foregut and hindgut are blind ended diverticula

midgut has opening at first and is continuous with yolk sac

Question 5

What does gut tube pinch off from yolk sac?

Answer 5

3rd week

Question 6

Where does the gut tube run from?

Answer 6

Stomatodeum (future mouth) to proctodeum (future anus) with an opening at umbilicus

Question 7

What is the internal ling of the primitive gut derived from?

Answer 7

Endoderm - future epithelial linings

Question 8

What is the external lining of the primitive gut tube derived from?

Answer 8

Splanchnic mesoderm - future musculature and visceral peritoneum

Question 9

What does the foregut mature into?

Answer 9

Oesophagus
stomach
pancreas
liver and gall bladder
duodenum proximal to bile duct entrance

Question 10

What does the midgut develop into?

Answer 10

Duodenum distal to entrance of bile duct
jejunum
ileum
cecum
ascending colon
proximal 2/3 transverse colon

Question 11

What does the hindgut develop into?

Answer 11

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

Question 12

What artery supplies the foregut?

Answer 12

Celiac trunk

Question 13

What artery supplies the midgut?

Answer 13

Superior mesenteric artery

Question 14

What artery supplies the hindgut?

Answer 14

Inferior mesenteric artery

Question 15

What is the intraembryonic coelom?

Answer 15

Begins as one large cavity

later subdivides by future diaphragm into abdominal and thoracic cavities

Question 16

What is the peritoneal cavity?

Answer 16

A potential space that under normal conditions should contain nothing

Question 17

What are the mesenteries?

Answer 17

Double layer of peritoneum suspending the gut tube from the abdominal wall which allows for a blood and nervous supply

Question 18

How is the mesentery formed?

Answer 18

Splanchnic mesoderm surround new gut, condensation of this mesoderm forms the mesentery

Question 19

What are the two mesenteries and where are they?

Answer 19

Dorsal mesentery suspends the entire gut tube from the dorsal body wall, ventral mesentery only in the region of foregut

Question 20

In the foregut how do the mesenteries divide the cavity?

Answer 20

Into the left and right sac

Question 21

What does the left sac contribute to?

Answer 21

The greater sac

Question 22

What does the right sac contribute to?

Answer 22

The lesser sac

Question 23

What are omenta?

Answer 23

Specialised regions of peritoneum

Question 24

What is the greater omentum?

Answer 24

Formed by dorsal mesentery

first structure seen when abdominal cavity is opened anteriorly

Question 25

What is the lesser omentum?

Answer 25

Formed from the ventral mesentery | free edge conducts the portal triad

Question 26

How are the omenta and the greater and lesser sacs formed?

Answer 26

Rotation of the stomach

Question 27

How does the stomach rotate?

Answer 27

In two directions | Around the longitudinal axis and around the anteroposterior axis

Question 28

What is the result of stomach rotation?

Answer 28

Greater and lesser curves lie first on the right and left sides then cardia and pyloris move horizontally pushing greater curve inferiorly puts the vagus nerves anterior and posterior to the stomach instead of left and right shifts cardia and pylorus from the midline moves lesser sac behind stomach creates greater omentum

Question 29

What is peritoneal reflection?

Answer 29

A change in direction - from parietal peritoneum to mesentery, from mesentery to viscera, peritoneum etc.

Question 30

What if there is no mesentery?

Answer 30

structures are not suspended within the abdominal cavity and are retroperitoneal

Question 31

Whats the different between retroperitoneal and secondary retroperitoneal?

Answer 31

Retroperitoneal is where they were never in the peritoneal cavity and never had a mesentery secondary retroperitoneal organs began development in the peritoneum and had a mesentery but during growth and development the mesentery was lost through fusion at posterior abdominal wall

Question 32

How does the oesophagus form?

Answer 32

In 4th week respiratory diverticulum forms in ventral wall of foregut at junction with pharyngeal gut Forms respiratory primordium ventrally and oesophagus dorsally

Question 33

What causes the respiratory primordium to become separate from the oesophagus?

Answer 33

Tracheoesophageal septum develops

Question 34

Name some problems that might occur from abnormal positioning of tracheoesophageal septum?

Answer 34

Proximal blind-ended tube | thracheoesophageal fistula

Question 35

How is the greater curve of the stomach created?

Answer 35

Faster growth of the dorsal border

Question 36

What foregut derived glands are formed in the ventral mesentery?

Answer 36

Liver biliary system part of pancreas (uncinate process and inferior head)

Question 37

What foregut derived glands are formed in the dorsal mesentery?

Answer 37

Pancreas - superior head, neck, body and tail

Question 38

What do the intestines have to develop outside the body?

Answer 38

The liver occupies a large proportion of the abdomen during development so there is not space

Question 39

How does the duodenum develop?

Answer 39

Develops from caudal foregut and cranial midgut grows rapidly forming a C shaped loop when the stomach rotates

Question 40

How does rotation of the stomach position the duodenum?

Answer 40

Causes duodenum to forma c shaped loop and pushes it to the right and then against the posterior abdominal wall

Question 41

What are the secondary retroperitoneal structure of the foregut?

Answer 41

Duodenum | pancreas