Development of the Peritoneum and Foregut Flashcards Preview

ESA 3 - Gastrointestinal System > Development of the Peritoneum and Foregut > Flashcards

Flashcards in Development of the Peritoneum and Foregut Deck (127):
1

What kind of folding does the embryo undergo in the fourth week?

  • Lateral 
  • Craniocaudal 

 

2

What is the importance of lateral folding of the embryo?

  • Creates ventral body wall
  • Primitive gut becomes tubular 

3

Draw a diagram illustrating lateral folding of the embryo. 

Label the tubular primitive gut

4

What is the importance of craniocaudal folding of the embryo?

Creates cranial and caudal pockets from the yolk sac endoderm

5

What is the significance of the cranial and caudal pockets of the yolk sac endoderm?

It is the beginning of primitive gut development

6

Draw a diagram illustrating craniocaudal folding of the embryo

7

What is the primitive gut tube lined with?

Endoderm 

8

What regions is the primitive gut tube divisible into?

  • Foregut
  • Midgut
  • Hindgut

 

9

What is the importance of the divisions of the primitive gut tube?

They remain fundamental to the anatomy of the adult GI tract, and determine its nerve and blood supply

10

When does the development of the primitve gut tube begin?

In the 3rd week

11

What is the first step in the development of the primitive fut tube?

It 'pinches off' from the yolk sac cavity 

12

Where does the primitive gut tube run?

From the stomatodeum rostrally to the procotdeum caudally

13

What is the stomatodeum?

Future mouth

14

What is the proctodeum?

Future anusu 

15

Where does the primitive gut tube have an opening?

At the umbilicus

16

What is the opening at the umbilicus in the primitive gut tube called?

The vitelline duct 

17

Where does the vitelline duct lead to?

The yolk sac

18

Draw a diagram of the primitive gut tube 

19

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

The endoderm (future epithelial linings)

20

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

Splanchnic mesoderm (future musculature, visceral peritoneum)

21

What is the primitive gut tube suspended in? 

Intraembryonic coelom 

22

What suspends the primitive gut tube in intraembryonic coelom? 

A double layer of splanchnic mesoderm 

23

What are the adult derivates of the foregut? 

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

 

24

What is the blood supply to the foregut? 

Celiac trunk 

25

What are the adult derivatives of the midgut? 

  • Duodenum (distal to entrance of bile duct)
  • Jejenum 
  • Ileum 
  • Cecum 
  • Ascending colon
  • Proximal 2/3 transverse colon 

 

26

What is the blood supply of the midgut? 

  • Superior mesenteric artery (SMA)
  • Superior mesenteric vein 

 

27

What is the parasympathetic innervation of the midgut? 

Vagus nerve

28

What is the sympathetic innervation of the midgut? 

Superior mesenteric ganglion and plexus 

29

What are the adult derivatives of the hindgut? 

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

 

30

What is the blood supply of the hindgut? 

  • Inferior mesenteric artery (IMA)
  • Inferior mesenteric vein (IMV)

 

 

31

What is the parasympathetic innervation of the hindgut?

Pelvic N. (S2/3/4)

32

What is the sympathetic innervation of the hindgut? 

Inferior mesenteric ganglion and plexus

33

What is the mesoderm surrounding the gut split into? 

Two layers;

  • Somatic mesoderm 
  • Splanchnic mesoderm 

34

What does the somatic mesoderm surrounding the gut develop into? 

Muscles and fasciae of the abdominal wall 

35

What does the splanchnic mesoderm surrounding the gut develop into? 

The smooth muscles of the gut wall 

36

What is the space created by the split in the mesoderm surronding the gut called?

The coelomic cavity 

37

What is the significance of the coelomic cavity?

It is the forerunner of the pleural cavity and peritoneal cavity 

38

What does the coelomic cavity surround? 

The primitive gut 

39

What happens as lateral folding of the embryo progresses? 

The two sides of the developing anterolateral abdominal wall meet in the midline, forming the linea alba 

40

How many openings are left once the linea alba has formed? 

One, at the umbilicus 

41

What is each side of the anterolateral abdominal wall formed of? 

Three layers of muscle; 

  • External oblique 
  • Internal oblique 
  • Transversus abdominis 

 

42

What is found anteriorly to the three layers of muscle forming the anterolateral abdominal wall?

A fourth muscle, the rectus abdominis 

43

What is found deep to all the muscle layers in the anterolateral abdominal wall? 

Transversalis fascia 

44

What lies externally to the anterolateral abdominal wall? 

Superficial fascia and skin 

45

What do the muscles and fascia of the abdoinal wall develop from? 

Somatic mesoderm 

46

Label this diagram 

  • A - Rectus abdominis 
  • B - Linea alba 
  • C - External oblique 
  • D - Internal oblique 
  • E - Transverse abdominis 
  • F - Transversalis fascia 
  • G - Peritoneum 

47

What is the inguinal canal? 

An oblique passage through the layers of the abdominal wall 

48

What is the significance of the inguinal canal in males? 

It allows the passage of the developing testis into the scrotum

49

Do the testis pierce the abdominal wall? 

No 

50

How do the testis get to their final position during development? 

The abdominal wall pushes them out ahead of its passage

51

What does the abdominal wall pushing the testes out form? 

The fascial coverings of the spermatic cord

52

What is the clinical significance of the inguinal canal? 

It remains a potential site of weakness and hernia formation throughout life 

53

What kind of malformation is an umbilical hernia? 

Congenital 

54

What happens in an umbilical hernia? 

The intestines protrude through the abdominal wall 

55

In whom are umbilical hernias common? 

Babies

56

Why are umbilical hernias common in babies? 

Because the gut forms outside the abdomen and later returns through an opening that becomes the umbilicus. This opening is a potential site of weakness, so abdominal contents can push against it and herniate 

57

What is the inguinal canal? 

 A passage through the layers of the abdominal wall 

58

What does the mesoderm surrounding the gut split into? 

Somatic and splanchnic mesoderm

59

What does the space between the somatic and splanchnic mesoderm form? 

The coelomic cavity 

60

How does the space between the somatic and splanchnic mesoderm form the coelomic cavity? 

Via lateral folding

61

As what does the intraembryonic coelom begin? 

One large cavity 

62

What later subdivides the intraembryonic coelom? 

The future diaphragm 

63

What does the diaphragm divide the intraembryonic coelom into? 

The abdominal and thoracic cavities 

64

Draw a diagram illustrating the formation of the intraembryonic coelom

65

What does the peritoneal membrane do? 

Lines the abdominal cavity and invests the viscera 

66

What happens to the peritoneal membrane during its development? 

It grows, changes shape, and specialises 

67

Why is the peritoneal 'cavity' a potential space only

Because under normal conditions, it should contain nothing

68

What is the entire developing gut attached to? 

The roof of the abdominal cavity 

69

How is the developing gut attached to the roof of the abdominal cavity? 

By a fold of mesoderm known as the dorsal mesentery 

70

What attaches to the floor of the abdominal cavity? 

The foregut 

71

How is the foregut attached to the floor of the abdominal cavity? 

Ventral mesentery 

72

Draw a diagram illustrating the attachments between the developing gut and the abdominal cavity

73

What do the dorsal and ventral mesenteries become? 

The various peritoneal folds and reflections that suspend the gut and give passage to the vessels and nerves in the adult 

74

What happens to the shape of the dorsal and ventral mesenteries? 

They often become complex

75

Why does the shape of the dorsal and ventral mesenteries often become complex? 

Due to the complexity of the changes in shape and position undergone by the developing gut 

76

What do the dorsal and ventral mesenteries in the region of the foregut do? 

Divide the cavity into left and right sacs 

77

What does the left sac of the preitoneal cavity contribute to? 

The greater peritoneal sac

78

What does the right sac of the peritoneal cavity contribute to? 

The lesser peritoneal sac 

79

Where does the lesser peritoneal sac come to lie? 

Behind the stomach 

80

Draw a diagram illustrating the greater and lesser peritoneal sacs, and the mesentery dividing them

81

What are the greater and lesser omenta? 

Specialised regions of peritoneum 

82

What is the greater omentum formed from? 

The dorsal mesentery of the stomach 

83

When would the greater omentum be the first structure to be seen? 

When the abdominal cavity is opened anteriorly 

84

What does the greater omentum connect? 

The greater curve of the stomach to the transverse colon

85

What is the lesser omentum formed from? 

The ventral mesentery of the stomach 

86

What does the lessr omentum connect? 

The lesser curve of the stomach to the liver 

87

What are the greater and lesser sacs, and the omenta formed by? 

The rotation of the stomach 

88

What is the widest part of the foregut? 

The stomach

89

How does the shape of the stomach change during development? 

Initially, it is symmetrical, and then as it enlarges in expands unevenly, mainly towards the left 

90

What creates the greater curvature of the stomach? 

The faster growth of the dorsal border 

91

In what manner does the primitive stomach rotate? 

In two directions, around the longitudinal axis and around the anteroposterior axis 

92

What is the result of stomach rotation? 

  • The original left side becomes anterior 
  • The original right side becomes posterior 
  • Vagus nerves lie anterior and posterior instead of left and right 
  • Shifts cardia and pylorus from the midline, pushing the greater curve inferiorly 
  • Moves the lesser sac behind the stomach 
  • Creates the greater omentum 

 

93

Draw a diagram illustrating the longitudinal rotation of the stomach

94

Draw a diagram illustrating the anteroposterior rotation of the stomach

  

95

What is peritoneal reflection? 

A change in direction, from parietal peritoneum to mesentery, from mesentery to visceral peritoneum etc

96

Draw a diagram illustrating peritoneal reflection

97

Give two parts of the GI tract that remain suspended from the posterior abdominal wall? 

  • The jejenum
  • The ileum

 

98

How do some parts of the GI tract remain suspended from the posterior abdominal wall? 

By mesentery 

99

What is the consequence of some parts of the GI tract remaining suspended from the psoterior abdominal wall? 

They remain mobile 

100

What are structures that are not suspended within the abdominal cavity called? 

Retroperitoneal 

101

What is meant by retroperitoneal? 

Were never in the peritoneal cavity and never had mesentery 

102

Give 3 examples of structures that are retroperitoneal

  • Aorta
  • Vena cava
  • Kidneys 

 

103

What is meant by secondary retroperitoneal? 

Began development invested by peritoneum, and had mesentery, but with successive growth and development, the mesentery is lost through fusion with the posterior abdominal wall 

104

Give three examples of structures that are secondary retroperitoneal

  • Ascending colon
  • Descending colon
  • Duodenum 

 

105

What happens to the duodenum and its mesentery during development? 

It is pushed against the posterior abdominal wall 

106

Why is the duodenum and its mesentery pushed against the posterior abdominal wall during development? 

Due to the rotation of the stomach and the large size of the liver 

107

What produces fusion fascia? 

The peritoneum of posteiror abdominal wall is 'squished together' with the duodenum and its mesentery, growing over it 

108

Is fusion fascia vascular or avascular? 

Avascular 

109

What is the consequence of fusion fascia being avascular? 

You can remove it to make the duodenum mobile again without causing any damage 

110

When does a respiratory diverticulum form?

In the 4th week 

111

Where does a respiratory diverticulum form? 

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

112

What does the respiratory diverticulum become?

  • The respiratory primordium ventrally
  • The oesophagus dorsally 

 

113

What divides the respiratory primordium and the oesophagus? 

The tracheoesophageal septum 

114

Draw diagrams illustrating the formation of the respiratory primordium and the oesophagus

115

What is the prevelance of oesophageal abnormalities? 

Up to 1 in 3,000 live births 

116

Draw a diagram illustrating the potential consequences of abnormal positioning of the tracheoesophageal septum? 

117

Where are the foregut derived glands formed? 

  • In the ventral mesentery
  • In the dorsal mesentery 

 

118

What foregut derived glands are formed in the ventral mesentery? 

  • Liver
  • Biliary system
  • Part of pancreas (ucinate process and inferior head)

 

119

What foregut derived glands are formed in the dorsal mesentery? 

Pancreas (superior head, neck, body, and tail) 

120

What is the earliest GI tract associated gland? 

The liver

121

What does the liver develop from? 

The hepatic bud within the ventral mesentery 

122

What is the significance of the liver during development? 

WIth regards to space 

 

It occupies a large proportion of the abdomen

123

Draw a diagram illustrating the development of the liver

124

What happens to the lumen of the duodenum in the 5th and 6th weeks? 

It is obliterated due to the lining growing so quickly 

125

What happens to the duodenum by the end of the embryonic period? 

It is recanalised 

126

What is the effect of the rotation of the stomach on the duodenum? 

It pushes it to the right, then back against the posterior abdominal wall 

127

Label this diagram 

  • A - Bare area 
  • B - Falciform ligament
  • C - Lesser omentum