GI development 1

Question 1

Name the 3 parts of the primitive gut tube:

Answer 1

1) Foregut
2) Midgut
3) Hindgut

Question 2

What name is given to the future mouth of the primitive gut tube?

Answer 2

Stomatodeum

Question 3

What is the Stomatodeum?

Answer 3

Future mouth of the primitive gut tube

Question 4

What name is given to the future anus of the primitive gut tube?

Answer 4

Proctodeum

Question 5

What is the Proctodeum?

Answer 5

Future anus of the primitive gut tube

Question 6

Which germ layer gives rise to the internal lining of the GI tract?

Answer 6

Endoderm

Question 7

Which germ layer gives rise to the external lining of the GI tract? (Musculature and peritoneum etc)

Answer 7

Splanchnic mesoderm

Question 8

What is the function of the Vitelline duct?

Answer 8

Connects the yolk sac to the hindgut

Question 9

What name is given to the duct which connects the yolk sac and hindgut?

Answer 9

Vitelline tract

Question 10

What is the name of the vestigial remnant of the vitelline duct, present in 2% of the population?

Answer 10

Meckel’s Diverticulum

Question 11

List the (GI) adult derivatives of the foregut:

Answer 11

• Oesophagus
• Stomach
• Liver
• Gall bladder
• Pancreas
• Proximal 1/4 of duodenum

Question 12

What is the blood supply of the adult derivatives of the foregut?

Answer 12

Coeliac trunk

Question 13

At which vertebral level does the Coeliac trunk branch from the abdominal aorta?

Answer 13

T12

Question 14

Name the 3 main branches of the Coeliac trunk:

Answer 14

1) Splenic artery
2) Common hepatic artery
3) Left gastric artery

Question 15

List the (GI) adult derivatives of the midgut:

Answer 15

• Distal 3/4 of duodenum
• Jejunum
• Ileum
• Caecum (+ appendix)
• Asc. colon
• Proximal 2/3rds Transverse colon

Question 16

Which 2 structures form from the junction between the foregut and midgut? What implications does this have on their blood supplies?

Answer 16

1) Pancreas
2) Duodenum
Mixed blood supplies (Coeliac trunk + SMA)

Question 17

What is the blood supply of the adult derivatives of the midgut?

Answer 17

Superior Mesenteric Artery (SMA)

Question 18

At what vertebral level does the SMA branch from the abdominal Aorta?

Answer 18

L1

Question 19

List the (GI) adult derivatives of the hindgut:

Answer 19

• Distal 1/3rd Transverse colon
• Desc. colon
• Sigmoid colon
• Rectum
• Upper anal canal

Question 20

What is the blood supply of the adult derivatives of the hindgut?

Answer 20

Inferior Mesenteric Artery (IMA)

Question 21

At what vertebral level does the IMA branch from the abdominal Aorta?

Answer 21

L3

Question 22

What are the main 3 branches of the IMA?

Answer 22

1) Left colic artery
2) Sigmoid artery
3) Superior Rectal artery

Question 23

What are the 3 main branches of the SMA?

Answer 23

1) Ileocolic artery
2) Right colic artery
3) Middle colic

Question 24

What structure divides the intraembryonic coelom into the thoracic and abdominal cavities?

Answer 24

Diaphragm

Question 25

Define mesentery:

Answer 25

Double layer of peritoneum - suspending gut tube from abdominal wall - allows conduit for blood + nerve supply - allows motility (when needed) - formed from condensation of splanchnic mesoderm

Question 26

Which type of mesentery suspends the fore-, mid- and hindgut from the abdominal walls?

Answer 26

``` Foregut = Ventral + Dorsal mesenteries Midgut = Dorsal only Hindgut = Dorsal only ```

Question 27

Which structures divide the peritoneal sac into left and right sacs? (the future greater and lesser sac's)

Answer 27

Ventral and Dorsal mesenteries

Question 28

Which mesentery forms the greater omentum?

Answer 28

Dorsal mesentery

Question 29

Which mesentery forms the lesser omentum?

Answer 29

Ventral mesentery

Question 30

Define omentum:

Answer 30

Fold of peritoneum which surrounds abdominal organs

Question 31

The ventral and dorsal mesenteries divide the peritoneal sac into left and right sac's. Which sac becomes the lesser sac?

Answer 31

Right sac --> Lesser sac

Question 32

What is the importance of the longitudinal rotation of the stomach?

Answer 32

- Lesser curvature now lies on RHS - Greater curvature now lies on LHS - Movement of mesenteries creates space behind stomach = Lesser sac

Question 33

What is the importance of antero-posterior rotation of the stomach?

Answer 33

- Cardia and pylorus move horizontally | - Greater curvature moves inferiorly

Question 34

What is the difference between primary and secondary retroperitoneal organs?

Answer 34

``` Primary = never had a mesentery (never in peritoneal cavity) Secondary = Had mesentery which fused with posterior abdominal wall, immobilising organ ```

Question 35

List the primary retroperitoneal organs:

Answer 35

- Kidneys - Bladder - Ureters - Rectum - Uterus (+ Aorta/IVC)

Question 36

List the secondary retroperitoneal organs:

Answer 36

- Duodenum - Pancreas - Asc + Desc colon

Question 37

What is the name given to the part of the peritoneum which covers secondary retroperitoneal organs?

Answer 37

Fusion fascia

Question 38

Which organs of the lower GI tract remain suspended from the posterior abdominal wall (do not become retroperitoneal)?

Answer 38

Jejunum | Ileum