Development of the Midgut and Hindgut Flashcards Preview

B - Embryology for EoY4 > Development of the Midgut and Hindgut > Flashcards

Flashcards in Development of the Midgut and Hindgut Deck (125)
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1

What does the midgut give rise to? 

  • Small intestine, including most of the duodenum post bile duct entry
  • Caecum and appendix
  • Ascending colon
  • Proximal 2/3 or transverse colon 

 

2

Draw a diagram illustrating the position of the midgut in an embryo

3

What causes the midgut to make a loop? 

It elongates enormously, and quickly runs out of space due to the large size of the developing liver 

4

What does the loop made by the midgut have at its axis? 

The superior mesenteric artery 

5

What is the loop made by the midgut connected to? 

The yolk sac

6

How is the midgut loop connected to the yolk sac? 

By the vitelline duct 

7

What are the limbs of the midgut loop called? 

Cranial and caudal limbs 

8

Label this diagram 

  • A - Cranial limb 
  • B - Superior mesenteric artery at axis 
  • C - Caudal limb 
  • D - Vitelline duct to yolk sac

 

  1. SMA
  2. Cranial 
  3. Caudal 

 

9

What are the derivatives of the cranial limb? 

  • Distal duodenum 
  • Jejunum 
  • Proximal ileum 

 

 

10

What are the derivates of the caudal limb? 

  • Distal ileum 
  • Cecum 
  • Appendix
  • Ascending colon 
  • Proximal 2/3 of transverse colon

 

11

What happens to the primary loop during the 6th week of development? 

It elongates very rapidly 

12

What happens to the liver during the 6th week of development? 

It grows very rapidly 

13

What is the problem with the rapid growth of both the liver and the primary loop? 

The abdominal cavity is too small to accomodate both

14

What is the result of the abdominal cavity being too small too accomodate the primary loop and the liver? 

Physiological herniation 

15

What is physiological herniation? 

Where the intestines herniate into the proximal umbilical cord, alongside the umbilical vessels 

16

What are the stages in rotation of the midgut loop? 

  1. First rotation 
  2. Second rotation 

 

17

By how much is the first rotation of the midgut loop? 

90 degrees

18

By how much is the second rotation of the midgut loop? 

180 degrees 

19

What happens in the first rotation of the midgut loop? 

During herniation into the umbilical cord, the midgut rotates around the axis formed by the SMA in a counter clockwise direction (cranial limb moves to back, caudal to the front) 

20

Draw a diagram illustrating what happens in the first rotation of the midgut loop? 

21

Does elongation of the small intestinal lumen continue during rotation? 

Yes 

22

What is the result of the elongation of the small intestinal loop continuing during rotation? 

The jejunum and ileum form a number of coiled loops 

23

What happens to the large intestine during rotation? 

It lengthens, but does not participate in the coiling phenomenon

24

When does the second rotation of the midgut loop occur? 

When it returns into the abdominal cavity, around week 10 

25

In what direction does the second rotation of the midgut loop occur? 

Turns 90 degrees counter-clockwise twice 

26

Draw a diagram illustrating the second rotation of the midgut loop 

27

In total, by how much does the midgut loop rotate? 

270 degrees counter-clockwise 

28

Which limb returns to the abdomen first? 

The cranial limb 

29

In what direction does the cranial limb move on return to the abdomen? 

To the left hand side 

30

What returns to the abdomen last following rotation? 

The cecal bud