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SOI2 > DEVELOPMENT DIGESTIVE > Flashcards

DEVELOPMENT DIGESTIVE Flashcards

1
Q

What are the divisions of a 4 week embryo’s abdominal cavity/GI tract?

A

Foregut
Midgut
Hindgut

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2
Q

What attaches the midgut to the abdominal wall?

A

Oropharyngeal membrane

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3
Q

What are the main branches of the abdominal aorta?

A

Celiac trunk
Superior mesentery artery
Inferior mesentery artery

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4
Q

What are secondary retroperitoneal viscera?

A

Viscera that transition from intraperitoneal –> retroperitoneal

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5
Q

What derives from the foregut?

A 
Esophagus
Stomach
1st & 2nd portions of duodenum
Pancreas
Liver
Gallbladder
Spleen (not derivative but categorised as it)
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6
Q

What derives from the midgut?

A 
Duodenum
Ascending & superior 2/3 of transverse colons
Ileum
Appendix
Jejunum
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7
Q

What derives from the hindgut?

A

Superior rectum
Inferior 1/3 of transverse colon
Descending colon
Sigmoid colon

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8
Q

What supplies the foregut derivatives?

A

Celiac trunk

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9
Q

What supplies the midgut derivatives?

A

Superior mesenteric artery

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10
Q

What supplies the hindgut derivatives?

A

Inferior mesentery artery

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11
Q

What is the mesentery and what is its function?

A

Peritoneum fold that connects intraperitoneal viscera to abdominal wall

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12
Q

What is the hepatic first effect?

A

Orally administered drugs will be metabolised in the liver and may change their composition
Slower effect than rectal drugs

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13
Q

What parasympathetically innervates the foregut, midgut and hindgut?

A

Foregut - vagus nerve
Midgut - vagus nerve
Hindgut - pelvic splachnic nerves (S2-S4)

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14
Q

What sympathetically innervates the foregut & midgut?

A

Thoracic splanchnic nerves (T5-T12)

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15
Q

Where do the nerves that sympathetically innervate the foregut & midgut synapse at?

A

Level of main arches of abdominal aorta

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16
Q

What sympathetically innervates the hindgut?

A

Lumbar splanchnic nerves (L1-L2)

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17
Q

Where do the nerves that sympathetically innervate the hindgut synapse at?

A

Inferior mesenteric artery

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18
Q

What is the crura?

A

Tendinous bands that attach posteriorly the diaphragm to lumbar vertebrae

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19
Q

What is the crura composed of?

A

Right crus

Left crus

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20
Q

What are the parietal branches of the abdominal aorta?

A

Inferior phrenics
Lumbars
Common iliac
Median sacral

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21
Q

What are the visceral branches of the abdominal aorta?

A 
Celiac trunk  (T12)
Superior mesenteric (L1)
Inferior mesenteric (L3)
Renal arteries (L1)
Gonadal arteries (L2)
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22
Q

What are the abdominal branches (direct tributaries) of the IVC?

A 
Right inferior phrenic vein
Right suprarenal
Renal
Right testicular (gonadal)
Lumbars 
Common iliac
Hepatic
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23
Q

Mnemonic to remember direct tributaries

A

Portal System Returns To Liver In Humans

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24
Q

What drains onto the left renal vein?

A

Left suprarenal
Left inferior phrenic
Left gonadal

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25
Q

Where does the right suprarenal vein drain onto?

A

IVC

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26
Q

What are the posterior & anterior vagal trunks (nerves)?

A

Branches of right & left vagus nerves (respectively)

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27
Q

What is the pathway of the anterior and posterior vagal trunk (nerves)?

A

Pass posterior to esophagus

Reach celiac branch

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28
Q

Where does the foregut extend from and to?

A

Starts with abdominal esopahagus

Ends halfway through descending part of duodenum

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29
Q

What is located halfway through the descending part of the duodenum?

A

Major duodenal papilla

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30
Q

What does the foregut encompass?

A 
Abdominal oesophagus
Stomach
Duodenum (superior to major papilla)
Liver
Pancreas
Gallbladder
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31
Q

What does the respiratory diverticulum split into in its dorsal portion?

A

Esophagus & trachea

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32
Q

What separates the esophagus from the trachea?

A

Tracoesophageal septum

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33
Q

What does the respiratory diverticulum split into in its ventral portion?

A

Larynx
Trachea
Bronchi
Lungs

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34
Q

What are possible malformations of the esophagus?

A

Tracoesophageal fistula
Stenosis
Congenital hiatal hernia

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35
Q

What does a trachoesophageal fistula consist of?

A

Connection btw. esophagus and trachea

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36
Q

What does a tracoesophageal fistula manifest as?

A

Prenatally - Polyhydramnios

Postnatally - regurgitation

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37
Q

What is the cause of esophageal stenosis?

A

Incomplete recanalization of esophagus (incomplete degeneration of epithelium & hollow gut tube

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38
Q

What does the recanalization of the esophagus consist of?

A

Gut tube is initially hollow
Endoderm proliferates rapidly & occludes lumen of gut tube
Apoptosis of endoderm causes recanalisation
Lumen open again (9th week)

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39
Q

What does the stomach initially appear as?

A

Dilation of foregut endoderm

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40
Q

3 key steps in development of stomach

A

1) Dilation
2) 90º clockwise rotation
3) Dorsal grows faster than ventral

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41
Q

What is the result of the rotation of the stomach?

A

Left side becomes anterior

Right side becomes posterior

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42
Q

How does the rotation of the stomach affect the orientation of the vagus nerves?

A

Left vagus becomes anterior

Right vagus becomes posterior

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43
Q

What is the final axis of the stomach?

A

Up & left

Down & right

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44
Q

Why is the stomach not floating?

A

Because it is attached to dorsal and ventral mesogastrium

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45
Q

Why is the liver on the right?

A

Due to stomach rotation

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46
Q

Why is the pancreas a secondary retroperitoneal viscera?

A

Attached by dorsal mesogastrium –> pushed towards dorsal wall
Derivative of dorsal mesogastrium

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47
Q

What forms the omental bursa?

A

Greater omentum

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48
Q

Why is there a decrease in the size of the omental bursa?

A

Because 2 of the 4 layers of the greater omentum fuse

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49
Q

What does the hematopoietic function rely on before the 6th week of development?

A

Extraembryonic mesoderm

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50
Q

What does the hematopoietic function rely on after the 6th week of development?

A

Liver

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51
Q

Why are the pancreas & duodenum secondary retroperitoneal viscera?

A

Because they rotate to the right into the dorsal mesentery

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52
Q

What are the 3 key steps in the development of the pancreas?

A

1) Formation of dorsal & ventral pancreatic buds
2) Rotation of pancreas to the right
3) Fusion of dorsal & ventral pancreas

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53
Q

What does the midgut initially consist of?

A

U-shaped loop

Superior & inferior branches Connected to dorsal wall by mesentery

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54
Q

What supplies the midgut loop and how does it do so?

A

Superior mesenteric artery

Perforates through mesentery

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55
Q

What does the superior branch of the midgut loop give rise to?

A

Intestinal loops

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56
Q

What does the inferior branch of the midgut loop give rise to?

A

Large intestine derivatives

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57
Q

What does physiological umbilical herniation imply?

A

Superior branch of midgut loop grows too much
Not enough space in abdominal cavity for intestinal loops
Intestinal loops herniate (perforate) into extra embryonic coelom in umbilical cord
90º counterclockwise rotation

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58
Q

What occurs as a result of physiological umbilical herniation?

A

Superior branch = right

Inferior branch = left

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59
Q

How and when does the reduction of the physiological midgut hernia take place?

A

180º counterclockwise rotation

10th week

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60
Q

What anomalies are associated with malrotation of gut?

A

Non rotation
Midgut volvulus
Reversed rotation

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61
Q

What occurs due to the anomaly of reversed rotation?

A

Duodenum anterior to colon

Superior mesenteric artery compresses transverse colon

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62
Q

What midgut anomalies are NOT associated with rotation?

A

Meckel’s diverticulum
Umbilical hernia
Omphalocele
Gastroschisis

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63
Q

Why does meckel’s diverticulum occur?

A

Persistence of vitelline duct

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64
Q

Why do umbilical hernias occur (prenatally)

A

Abdominal musculature does not close properly

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65
Q

Why does an omphalocele occur?

A

Failure in reduction of physiological midgut hernia –> intestinal loops do not return to body cavity

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66
Q

Why does gastroschisis occur?

A

Due to incomplete closure of lateral foldings in 4th week

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67
Q

Where does the hindgut extend to and from?

A

Starts slightly before left colic flexure

Ends halfway through anal canal

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68
Q

What is the cloaca?

A

Caudal portion of hindgut enclosed by cloacal membrane

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69
Q

What is the urorectal septum?

A

Septum that will grow between the allantois and the hindgut to separate the urogenital sinus from the anorectal canal

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70
Q

What develops within the allantois –> urogenital sinus?

A

Bladder

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71
Q

What area is located between the urogenital sinus (genitals) and the rectum (anus?

A

Perineum

72
Q

What are the 2 divisions of the anal canal?

A

Anal pit

Anal columns

73
Q

What separates the anal pit from the anal columns?

A

Pectinate line

74
Q

What causes an imperforate anus?

A

Persistence of cloacal membrane

75
Q

What is the most common cause of congenital abnormalities of the hindgut?

A

Incorrect development of urorectal septum

76
Q

What is Hirschsprung’s disease AKA congential aganglionic megacolon?

A

Distal colon is aganglionic (no communication with CNS) therefore delay in progression of stool through intestines

77
Q

What is the peritoneum?

A

Thin serous membrane lining abdominal cavity

78
Q

What is the difference between parietal and visceral peritoneum?

A

Parietal lines walls of abdominal & pelvic cavities

Visceral covers organs

79
Q

What are intraperitoneal viscera?

A

Viscera FULLY surrounded by peritoneum

WITHIN peritoneal cavity

80
Q

What are primary retroperitoneal viscera?

A

Organs covered by peritoneum only on anterior surface

Lie WITHIN posterior abdominal wall

81
Q

What are secondary retroperitoneal viscera?

A

Initially intraperitoneal but lose mesentery due to development

82
Q

What structures are continuous within the peritoneal cavity?

A 
Greater sac (peritoneal cavity) 
&
Lesser sac (omental bursa)
83
Q

What does the greater omentum fuse with?

A

Transverse mesocolon

84
Q

What does the greater omentum attach to?

A

Greater curvature of stomach

1st part of duodenum

85
Q

What does the lesser omentum attach to and from?

A

From lesser curvature of stomach & 1st part of duodenum

To inferior part of liver

86
Q

What is the lesser omentum divided into?

A

Hepatoduodenal ligament

Hepatogastric ligament

87
Q

What are peritoneal reflections?

A

Point where mesenteries connect to the dorsal wall

88
Q

What is the parietal peritoneum innervated by?

A

Somatic afferent fibers of spinal and phrenic nerves

89
Q

What is the visceral peritoneum innervated by?

A

Visceral afferent fibers from autonomous N.S

90
Q

What arteries supply the abdominal esophagus (at level of T10)?

A

Celiac trunk

  • Left gastric artery
  • Left inferior phrenic artery
91
Q

What are the main regions of the stomach?

A

Cardia
Fundus
Body
Pylorus

92
Q

What arteries supply the stomach?

A

Celiac trunk

  • Left gastric artery
  • Common hepatic artery
  • Splenic artery
93
Q

What branches does the left gastric artery give off?

A

Esophageal branches

94
Q

What branches does the common hepatic artery give off?

A

Right gastric artery
Gastroduodenal artery
Proper hepatic artery

95
Q

What branches does the splenic artery give off?

A

Left gastro-mental artery

Short gastric arteries

96
Q

What innervates the stomach (sympathetically)?

A

Greater splachnic nerve (T5-T9)

Lesser splachnic nerve (T10-T11)

97
Q

What innervates the stomach parasympathetically?

A

Vagus (synapse in wall of stomach)

98
Q

What connects the liver to the anterior wall?

A

Falciform ligament

99
Q

What is continuous (caudally) with the falciform ligament?

A

Teres ligament

100
Q

What branches does the falciform ligament give off in the diaphgram?

A

Posterior (right) and Anterior (left) coronary ligaments

101
Q

What branches do the anterior and posterior coronary ligaments give off?

A

Right and left triangular ligaments respectively

102
Q

Where does the blood of the liver metabolism drain onto?

A

Systemic circulation via IVC

103
Q

What do the gastric veins drain?

A

All of the blood of the foregut directly into portal vein

104
Q

Where are the portosystemic anastamosis located?

A

1: level of esophageal veins (draining onto left gastric vein) that drain to azygos system
2: level of rectum

105
Q

In which veins are varicosities most common in?

A

Esophageal and gastric veins

106
Q

What is the transpyloric plane?

A

Imaginary horizontal plane at L1 level

107
Q

What are the segments of the duodenum (in order)?

A

1) Superior
2) Descending
3) Inferior
4) Ascending

108
Q

Which duodenal segments are intraperitoneal and which are retroperitoneal?

A

Intra: 1 and 4
Retro: 2 and 3

109
Q

Arterial supply of duodenum

A 
Proximal: 
- Gastroduodenal
- Superior pancreaticoduodenal
Distal: 
- Superior mesenteric 
- Inferior pancreaticoduodenal
110
Q

What are the main parts of the pancreas?

A

Head
Neck
Body
Tail

111
Q

Which parts of the pancreas are intraperitoneal and which are retroperitoneal?

A

Intra: tail
Retro: head, neck and body

112
Q

Where do the main pancreatic duct & bile duct enter into the duodenum?

A

Level of major duodenal papilla (2nd portion = descending)

113
Q

Arterial supply of pancreas

A

Posterior wall of pancreas
Splenic artery gives 2 branches:
- dorsal pancreatic artery
- greater pancreatic artery

114
Q

What is the exact location of the spleen?

A

Left hypochondrium associated with rib X

115
Q

What is the connection between the spleen and the stomach?

A

Gastrosplenic ligament

116
Q

What is the connection between the spleen and the left kidney?

A

Splenorenal ligament

117
Q

BLOOD supply of the spleen

A

Splenic artery

Splenic vein

118
Q

What are the impressions on the visceral surface of the spleen?

A

Splenic - colon
Visceral - kidney
Diaphragmatic - stomach

119
Q

How does the splenic vein pass in relation to the pancreas?

A

Posterior to pancreas

120
Q

What is the main nerve that innervates (sympathetically) the spleen?

A

Greater thoracic splanchnic nerve

121
Q

Where do the visceral afferent (sensory) neurons originate from?

A

Dorsal ganglia of afferent fibers from T5-L1 (foregut, midgut, hindgut)

122
Q

What does the referred pain of the foregut address?

A

Visceral afferent innervation from T5-T9

123
Q

What does the referred pain of the midgut address?

A

Visceral afferent innervation from T10-T11

124
Q

What does the referred pain of the hindgut address?

A

Visceral afferent innervation from T12-L1

125
Q

Where does the somatic pain of the diaphragm arise from?

A

Phrenic nerves from:

  • C3 –> C5
  • T5 –> T11
126
Q

Where do jejunal and ilieal arteries arise from?

A

Superior mesenteric artery

127
Q

What kind of loops do jejunum and ileum have?

A

Jejunum - Horizontal loops

Ileum - Vertical loops

128
Q

Arterial supply to the small intestine

A

Superior mesentery
Jejunal and ileal arteries
Vasa recta

129
Q

The vasa recta of which intraperitoneal organ of the small intestine are longer?

A

Jejunum

130
Q

From outermost to innermost what are the common layers between the jejunum and ileum?

A 
Serosa
Longitudinal Muscular
Circular muscular
Submucosa
Mucosa
Circular folds
Solitary lymphoid nodule
131
Q

What layer is specific to the ileum?

A

Aggregated lymphoid nodules

132
Q

Are folds more prominent in the jejunum or in the ileum? Why?

A

In the jejunum (mucuous) for good absorption

133
Q

What are the segments of the large intestine?

A

Ascending colon
Transverse colon
Descending colon
Sigmoid colon

134
Q

What segments of the large intestine are intraperitoneal?

A

Sigmoid colon

Transverse colon

135
Q

What segments of the large intestine are retroperitoneal?

A

Ascending colon

Descending colon

136
Q

What are 3 key characteristics of the colon?

A

Omental appendices
Taeniae coli
Haustras

137
Q

What are omental appendices?

A

Small pouches (folds) of peritoneum filled with fat

138
Q

What are taenia coli?

A

Longitudinal folds of smooth muscle on the outside of “4 colons”

139
Q

What are haustrum?

A

Pouches of colon caused by sacculation (sacs joined together)

140
Q

What are the transverse colon’s relations?

A

Right colic flexure

Left colic flexure

141
Q

How are each of the segments of the colon (ascending, transverse, descending, sigmoid) organised in the 9-region organisational pattern?

A

Ascending - right flank
Descending - left flank
Sigmoid & transverse - pubis

142
Q

Arterial supply of colon arising from the superior mesenteric artery

A

Branches to the RIGHT
Ileocolic
Right colic
Middle colic

143
Q

Arterial supply of colon arising from the inferior mesenteric artery

A

Branches to the LEFT
Left colic
Sigmoid
Superior rectal

144
Q

Where do anastomosis branch off in the arterial supply of the colon?

A

Middle colic artery

Left colic artery

145
Q

Describe the venous drainage of the colon (in terms of right vs left)

A

Right to superior mesenteric vein

Left to inferior mesenteric vein

146
Q

What sympathetically innervates the large intestine?

A

Thoracic splanchnic nerves (greater T5-T9 & lesser T10-T11)

Lumbar splanchnic nerves (L3-L4)

147
Q

What parasympathetically innervates the large intestine?

A

Vagus

Pelvic splanchnic

148
Q

What is the ileocecal junction?

A

Junction btw. small intestine & large intestine

149
Q

Where does the teania coli end?

A

Appendix (subcecal & pelvic orientations)

150
Q

What is the enteric nervous system?

A

Local nervous system present ONLY in GI tract
Independent of CNS
Controlled by ANS

151
Q

What sympathetically innervates the small intestine?

A

Greater splanchnic nerve (T5-T9)

Lesser splanchnic nerve (T10-T11)

152
Q

What parasympathetically innervates the small intestine?

A

Vagus

153
Q

What are the 3 functions of the enteric system?

A

Gastric secretion
Gastrointestinal blood flow
Peristalsis

154
Q

What are the plexus of the enteric system?

A

Myenteric

Submucosal

155
Q

At what level is the myenteric plexus located?

A

Level of circular muscle layer

156
Q

At what level is the submucosal plexus located?

A

Submucosa layer

157
Q

What is the pelvic floor?

A

Muscles located between coccyx & pubic bone that support bowel, bladder, uterus and vagina

158
Q

What are the main muscles of the pelvic floor?

A

Iliococcygeous
Pubococcygeous
Puborectalis

159
Q

What is the anorectal junction?

A

Ring that connects the anus with the rectum

160
Q

What is the anorectal flexure?

A

A bend at anorectal junction as the rectum passes through the pelvic diaphragm muscles

161
Q

What is the orientation of the anorectal flexure?

A

80º

162
Q

What is the ischioanal/ischiorectal fossa?

A

Triangular shaped pyramid filled with fat lateral to anal canal & below pelvic diaphragm

163
Q

In what part is the ischioanal fossa covered COMPLETELY with peritoneum?

A

Proximal portion

Lateral sides

164
Q

In what surfaces is the ischioanal fossa covered ONLY ANTERIORLY with peritoneum?

A

Middle portion

165
Q

In what surfaces is the ischioanal fossa NOT covered at all with peritoneum?

A

Distal portion

166
Q

What are the transverse mucosal rectal folds?

A

Folds of the rectal wall (that function as valves) that protrude into the rectum

167
Q

What are prominent transverse mucosal folds?

A

Superior rectal valve
Middle rectal valve
Inferior rectal valve

168
Q

Arterial supply of the rectum

A

Superior rectal artery
Middle rectal artery
Inferior rectal artery

169
Q

Arterial supply of the anal canal

A

Middle rectal artery

Inferior rectal artery

170
Q

Venous drainage of rectum & anal canal

A

Upper 2/3: superior rectal vein –> inferior mesenteric vein & portal vein
Lower 1/3: middle rectal vein

171
Q

Where are the anastomosis of the rectum and anal canal located?

A

Upper part of the anal canal

Between portal veins (superior rectal veins) and systemic veins (middle & inferior rectal veins)

172
Q

What are hemorrhoids?

A

Swollen veins in lower rectum

173
Q

What innervates the rectum & anal canal (above pectinate line)?

A

Visceral innervation via inferior hypogastric plexus

174
Q

What innervates the rectum & anal canal (below pectinate line)?

A

Sommatic innervation via inferior rectal nerves

175
Q

What allows conscious control of defecation?

A

External anal sphincter control by somatic nerve supply from inferior anal branch of pudendal nerve

176
Q

How does the involuntary control of defecation work?

A

Via the rectoanal inhibitory reflex

177
Q

What does the rectoanal inhibitory reflex imply?

A

Involuntary internal anal sphincter relaxation in response to rectal distension

SOI2 (9 decks)

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