EX2 Embryology

Question 1

Which germ layer forms the epithelial lining and glands of the GI tract

Answer 1

endoderm

Question 2

The endoderm that dorms the innermost lining of the gut tube is derived from where

Answer 2

the dorsal portion of the yolk sac

Question 3

This duct connects the midgut and the yolk sac

Answer 3

vitelline duct

Question 4

This membrane ruptures at week 4 and provides a continuity between the oral cavity and the foregut

Answer 4

oropharyngeal membrane; allows for swallowing of amniotic fluid

Question 5

This membrane ruptures at week 7 and allow for urination and defication

Answer 5

cloacal membrane

Question 6

Which germ layer forms the smooth muscles and the connective tissues of the GI tract

Answer 6

splanchnic mesoderm

Question 7

This is the serous membrane lining the abdominal cavity and organs

Answer 7

peritoneum

Question 8

This type of peritoneum lines the abdominal cavity

Answer 8

parietal peritoneum

Question 9

This type of peritoneum lines the organs

Answer 9

visceral peritoneum

Question 10

This is a double layer of peritoneum that suspends an organ from the body wall

Answer 10

mesentery

Question 11

True or False

Mesentery can contain CT, blood vessels, lymphatics, and/or nerves

Answer 11

True

Question 12

The peritoneum and mesentery are derived from what germ layer

Answer 12

sphanchnic mesoderm

Question 13

At what level of the GI tract does the ventral mesentery exist

Answer 13

foregut; it is resorbed inferior to it

Question 14

The ventral mesogastrium is divided into which two segments due to the outgrowth of which organ

Answer 14

falciform ligament
lesser omentum
liver

Question 15

The lesser omentum (derived from what?) splits into what ligaments

Answer 15

LO is derived from ventral mesogastrium
hepatogastric ligament
hepatouodenal ligament

Question 16

The dorsal mesogastrium forms what

Answer 16

greater omentum

Question 17

The dorsal mesentery forms what four structures

Answer 17

dorsal mesogastrium
mesoduodenum
mesentery proper
mesocolon

Question 18

The neural crest cells migrate into the walls of GI tract to form what

Answer 18

enteric nervous system (intrinsic nervous system)

Question 19

This section of the GI tract is from the mouth to the first 1/2 of the duodenum

Answer 19

foregut

Question 20

This section of the GI tract is from the second 1/2 of the duodenum to the first 2/3 of the transverse colon

Answer 20

midgut

Question 21

This section of the GI tract is from the last 1/3 of the transverse colon to the anus

Answer 21

hindgut

Question 22

The main blood supply to the GI tract is what

Answer 22

abdominal aorta (and its 3 branches)

Question 23

The blood supply to the foregut is supplied via which artery

Answer 23

celiac trunk

Question 24

The blood supply to the midgut is supplied via which artery

Answer 24

superior mesenteric artery

Question 25

The blood supply to the hindgut is supplied via which artery

Answer 25

inferior mesenteric artery

Question 26

The blood supply to the pharynx is supplied via which artery

Answer 26

pharyngeal arch

Question 27

What six main structures are a part of the foregut

Answer 27

``` pharynx lower respiratory system esophagus stomach proximal 1/2 of duodenum associated organs (pancreas, liver, gall bladder, etc.) ```

Question 28

The foregut/midgut divide is typical where

Answer 28

after the entrance of the pancreatic and bile ducts in the duodenum

Question 29

The esophagus develops as the portion of the foregut immediately (cranial/caudal) to the pharynx

Answer 29

caudal

Question 30

This appears on the ventral side of the foregut and will become the trachea, respiratory tree, and lungs, during what week

Answer 30

respiratory diverticulum | week 4

Question 31

This appears from the lateral sides of the foregut, diving the foregut into the lower respiratory tract and esophagus

Answer 31

tracheoesophageal septum

Question 32

This is the abnormal narrowing of a lumen/orifice (tubular organ or structure)

Answer 32

stenosis

Question 33

This is a condition in which a body lumen or orifice is abnormally closed or absent

Answer 33

atresia

Question 34

Causes of stenosis/atresia can include what four things

Answer 34

failure to reanalyze following a temporary epithelial plug adequate blood supply fails to develop accidents that compromise blood flow mechanical obstruction

Question 35

This is an abnormal passageway between two organs/vessels or between an organ and the external environment

Answer 35

fistula

Question 36

Esophageal atresia and trachesophageal fistula can lead to what

Answer 36

risk of polyhydraminos (too much amniotic fluid)

Question 37

During week 4, a portion of the foregut begins to dilate uniformly, this becomes what?

Answer 37

the stomach

Question 38

As the stomach enlarges, its dorsal side expands faster than the other sides and it will be come the what? and the ventral side becomes this?

Answer 38

greater curvature | lesser curvature

Question 39

The stomach will undergo a rotation that is which direction (this is caused by uneven distribution of weight)

Answer 39

90° clockwise rotation

Question 40

During the stomachs 90° clockwise rotation, the ventral side ends up on what side and is supplied by what nerve

Answer 40

right side supplied via the left vagus | the dorsal side (left) is supplied via the right vagus

Question 41

This is caused by the circular smooth muscles constricting the pyloric lumen preventing passage of the stomach contents to the SI

Answer 41

hypertrophic pyloric stenosis

Question 42

As the stomach rotates, this is carried to the left

Answer 42

dorsal mesogastrium

Question 43

As the dorsal mesogastrium is carried to the left by the stomach, it enlarges this into a sizable recess between the stomach and posterior abdominal wall

Answer 43

omental bursa (lesser sac of peritoneum)

Question 44

This organ forms between two leaves of dorsal mesogastrium during week 5

Answer 44

spleen

Question 45

This forms as a C-shaped loop distal to the stomach; supplied by both the celiac trunk and SMAl where the pancreatic and common bile ducts empty

Answer 45

duodenum

Question 46

As the stomach rotates CW, it drags the distal duodenum and pancreas to where they become this; their dorsal mesenteries are lost

Answer 46

retroperitoneal (secondarily)

Question 47

This is the failure of the lumen to recanalize in the duodenum by week 8; vomit will either contain or not contain bile depending on where the obstruction is located

Answer 47

duodenal stenosis and atresia

Question 48

This emerges ventrally from endoderm of the distal foregut and grows superiorly toward the septum transvedsum (diaphragm) and gives rise to what three things

Answer 48

hepatic diverticulum | liver, gall bladder, and bile ducts

Question 49

This organ emerges from distal foregut as two endodermal buds (ventral and dorsal)

Answer 49

pancreas

Question 50

True or False | The ventral bud of the pancreas does not fuse with the dorsal bud

Answer 50

False; as the duodenum rotates, the ventral bud swings and fuses with the dorsal bud

Question 51

The ventral bud go the pancreas becomes what two things

Answer 51

uncinate process | inferior portion of head of pancreas

Question 52

The main pancreatic duct forms from which two ducts buds

Answer 52

distal portion of dorsal bud duct and ventral bud duct

Question 53

The accessory pancreatic duct forms from what duct bud

Answer 53

proximal dorsal bud duct

Question 54

This is caused when the ventral bud of the pancreas develops into two portions and they fail to fuse resulting in one wrapping around the duodenum then fusing

Answer 54

annular pancreas

Question 55

The midgut is composed of these six main structures

Answer 55

``` distal 1/2 of duodenum jejunum ileum cecum and appendix ascending colon proximal 2/3 of transverse colon ```

Question 56

The cranial limb of the midgut U-shaped loop forms which three structures

Answer 56

distal duodenum jejunum proximal ileum

Question 57

The caudal limb of the midgut U-shaped loop forms which four structures

Answer 57

distal ileum cecum and appendix ascending colon proximal 2/3 of transverse colon

Question 58

This is when there is insufficient room in the abdominal cavity and it leads to temporary herniation of midgut loop into the proximal umbilical cord

Answer 58

physiological umbilical herniation

Question 59

This is a persisting umbilical herniation; viscera covered by amnion and within proximal umbilical cord

Answer 59

congenital omphalocoele

Question 60

This is when a hernia is through the body wall and does not involve the umbilical cord; exposure to amniotic fluid can damage the viscera

Answer 60

gastrochisis

Question 61

During week 6 the midgut undergoes what type of rotation

Answer 61

90° counterclockwise | SMA is axis of rotation

Question 62

During week 10 the midgut undergoes a second rotation of which is what?

Answer 62

180° counterclockwise which brings the intestines into normal position (270° total rotation)

Question 63

True or False | The ascending and descending colon are intraperitoneal

Answer 63

False; they become secondarily retroperitoneal; their dorsal mesenteries are lost after fusion with parietal peritoneum of posterior abdominal wall

Question 64

These five structures are considered intraperitoneal

Answer 64

``` proximal duodenum jejunum ileum transverse colon sigmoid colon ```

Question 65

These five structures are considered retropeitoneal

Answer 65

``` distal duodenum pancreas ascending colon descending colon kidneys (form retroperitoneal) ```

Question 66

This is the result if the caudal limb returns first from the midgut loop

Answer 66

left-sided colon

Question 67

If there is an 180° clockwise (instead of counterclockwise) it results in a net 90° clockwise rotation which causes this to happen

Answer 67

the duodenum is now ventral to the TVC (doesn't become retroperitoneal)

Question 68

This is caused by abnormal rotation which may cause intestinal loop twist around mesenteric attachment site; can result in bowel obstruction/compromised blood flow leading to stenosis, necrosis, etc.

Answer 68

volvulus

Question 69

The recanalization of the midgut loop occurs during what week

Answer 69

week 8 | the epithelial cells occlude at week 6 and dissolve at week 8

Question 70

This is a remnant of the vitelline duct persisting as a finger-like out-pouching of the ileum about 40-60cm from the ileocecal junction; may contain tissue/gastric mucosa that secretes acid; causing ulcers/bleeding

Answer 70

Meckel's (ileal) diverticulum

Question 71

What are the three variations of a persistent vitelline duct

Answer 71

vitelline fistula vitelline cyst vitelline ligament

Question 72

The hindgut is composed of these five structures

Answer 72

``` distal 1/3 transverse coon descening colon sigmoid colon rectum superior portion of anal canal ```

Question 73

These two structures are derived from the posterior portion of the cloaca after it is partitioned by the urorectal septum

Answer 73

rectum | superior portion of anal canal

Question 74

This grows inferiorly toward the cloacal membrane dividing it into urogenital and anal membranes

Answer 74

urorectal septum

Question 75

The urorectal septum partitions the cloaca into what two things

Answer 75

``` urogenital sinus (ventrally) anorectal cana (dorsally) ```

Question 76

What two arteries supply the anal canal

Answer 76

superior rectal artery supplies the portion of the anal canal from the hindgut inferior rectal artery supplies the portion distal to that

Question 77

This form if the urorectal septum fails to completely separate the hindgut from the urogenital sinus or if the cloaca is too small

Answer 77

hindgut fistula (anal canal not connected to anal pit)

Question 78

This disease is a result of when neural crest cells fail to migrate to form the enteric nervous system; causing constriction of the aganglionic portion and bowel distending proximal to the constriction

Answer 78

Hirschspring's disease (aganglionic megacolon)