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Flashcards in Embryology 1 Deck (45):
1

When does embryonic folding take place

Week 4

2

Consequences of lateral folding

Creates ventral body wall
Primitive gut tube becomes tubular

3

Consequences of craniocaudal folding

Creates cranial and caudal pockets from yolk sac endoderm

4

Divisions of the primitive gut tube

Foregut
Midgut
Hindgut

5

When does the primitive gut tube begin to develop

Week 3 when it pinches off from the yolk sac cavity

6

Where does the primitive gut tube run from and to

From the stomatodeum to the proctodeum

7

What is the opening of the primitive gut tube called and where is it

Vitelline duct at the umbilicus

8

What are the origins of the internal and external lining of the primitive gut tube

Internal lining - endoderm
External lining - splanchnic mesoderm

9

What is the intraembryonic coelom/ coelomic cavity

Cavity created between the somatic and splanchnic mesoderm layers which the primitive gut tube is suspended in

10

Adult derivatives of foregut

Oesophagus
Stomach
Pancreas
Liver
Gall bladder
Duodenum proximal to entrance of bile duct

11

Adult derivatives of midgut

Duodenum distal to entrance of bile duct
Jejunum
Ileum
Caecum
Ascending colon
Proximal 2/3 transverse colon

12

Adult derivatives of hindgut

Distal 1/3 transverse colon
Descending colon
Sigmoid colon
Rectum
Upper anal canal
Internal lining of bladder and urethra

13

Blood supply of foregut

Celiac trunk

14

Blood supply and innervation of midgut

Superior mesenteric artery and vein

Parasympathetic - vagus nerve
Sympathetic - superior mesenteric ganglion and plexus

15

Blood supply and innervation of hindgut

Inferior mesenteric artery and vein

Parasympathetic - pelvic nerve (S2-4)
Sympathetic - inferior mesenteric ganglion and plexus

16

Adult derivative of somatic mesoderm surrounding the gut

Muscles and fascia of abdominal wall

17

Adult derivative of splanchnic mesoderm surrounding the gut

Smooth muscle of gut wall

18

How does the linea alba form

Progression of lateral folding leads to the 2 sides of the developing anterolateral abdominal wall to meet in the midline

19

What is the inguinal canal and what does it allow in males

Oblique through the layers of the abdominal wall
In males, it allows passage of developing testes into the scrotum

20

What is an inguinal hernia

Abdominal contents push against the inguinal canal and herniate through as it is a potential site of weakness

21

What is an umbilical hernia

Congenital malformation
Abdominal contents push against the umbilicus and herniate through as it is a potential site of weakness

22

How is the intraembryonic coelom divided and by what

Diaphragm divides the intraembryonic coelom into the:
Abdominal cavity
Thoracic cavity

23

What connects the primitive gut tube to the abdominal wall

Dorsal mesentery - foregut, midgut and hindgut to the roof of the abdominal cavity
Ventral mesentery - foregut to the floor of the abdominal cavity

24

What do the dorsal and ventral mesenteries in the foregut region divide the peritoneal cavity into

Greater peritoneal sac (left)
Lesser peritoneal sac (right)

25

What is an omentum

A double layered extension/fold of peritoneum that passes from the stomach and proximal duodenum to adjacent abdominal organs

26

What is the greater omentum

4 layered peritoneal fold that descends from the greater curve of the stomach, folds back, and attaches to the anterior transverse colon and its mesentery
(Formed from dorsal mesentery of stomach)

27

What is the lesser omentum

Double layered peritoneal fold that connects the lesser curvature of the stomach and proximal duodenum to the liver
It's made up of the hepatogastric and hepatoduodenal ligaments
(Formed from ventral mesentery of stomach)

28

How do the omenta form

Rotation of the stomach

29

How is the greater curvature of the stomach created

Dorsal border of stomach grows faster than the ventral border

30

What axes does the primitive stomach rotate about

Longitudinal
Anteroposterior

31

Consequences of stomach rotation

Original left side becomes anterior (greater sac)
Original right side becomes posterior (lesser sac)
Vagus nerve lies anterior/posterior instead of left/right
Shifts cardia and pylorus from the midline
Creates the greater omentum

32

What is meant by a peritoneal reflection

A change in direction/reflections of peritoneum
- mesentery to visceral peritoneum (and vice versa)
- mesentery to parietal peritoneum (and vice versa)

33

What determines the mobility of abdominal contents

Whether it has a mesentery or not

34

Define retroperitoneal organs and give some examples

Were never in the peritoneal cavity and therefore don't have a mesentery
E.g kidneys, aorta, oesophagus

35

Define secondary retroperitoneal organs and give some examples

Began development invested by peritoneum and had a mesentery but with progressive growth the mesentery is lost by fusion at the posterior abdominal wall
E.g ascending colon, descending colon, duodenum

36

Why is the duodenum secondary retroperitoneal

Rotation of the stomach pushes the duodenum against the posterior abdominal wall because the liver is so large

37

How is fusion fascia created

Peritoneum of the posterior abdominal wall is squished together with the duodenum and its mesentery and grows over it, creating fusion fascia

38

How can the duodenum be made mobile

Removal of fusion fascia (avascular so no damage)

39

What happens to the duodenum during weeks 5-6

Lumen is obliterated due to rapid growth of its lining
It's recanalised by the end of the embryonic period (before week 9)

40

When and where is the respiratory diverticulum created

Week 4
In the ventral wall of the foregut at the junction with the pharyngeal gut

41

What does the respiratory diverticulum become and how

Ventrally - respiratory primordium
Dorsally - oesophagus
Divided by the tracheoesophageal septum

42

Incidence of abnormal positioning of the tracheoesophageal septum

Up to 1 per 3000 live births

43

Which foregut derived glands are formed in the ventral mesentery

Liver
Biliary system
Ucinate process and inferior head of pancreas

44

Which foregut derived glands are formed in the dorsal mesentery

Superior head, neck, body and tail of pancreas

45

What does the liver develop from

Hepatic bud