101b GI Structure

Question 1

What masses form the intracembryonic coelom?

Answer 1

lateral plate and cardiogenic mesoderm - hollow out to form a U-shaped tube

Question 2

what embryonic structures separate the pleural and peritoneal cavities in early development?

Answer 2

septum transversum

plueroperitoneal membranes

Question 3

what are the 4 primordia for the adult diaphragm?

Answer 3

septum transversum (central tendon)
mesentery of esophagus (diaphragm crura)
pleuroperitoneal membranes
muscles from the body wall

Question 4

At what level does the septum transversum/diaphragm form in the embryo? Nerve supply?

Answer 4

C3,4,5 - with cervical somites

phrenic nerve

Question 5

Diaphragmatic hernia - description, types

Answer 5

abdominal contents into thorax; can occur in infants from failure of pleuroperitoneal membrane
types - sliding hiatal AND paraesophageal

Question 6

sliding hiatal hernia

Answer 6

most common

stomach slides through diaphragm opening for esophagus which displaces GE junction up

Question 7

paraesophageal hernia

Answer 7

GE junction is normal but stomach fundus protrudes through esophageal opening with it’s own thin layer of peritoneum

Question 8

omphalocele

Answer 8

• congenital umbilical hernia of the midgut
• midgut fails to retreat back into abdomen during development
• covered by peritoneum

Question 9

gastroschisis

Answer 9

• body wall defect
• can be in thorax, abdomen, or pelvis
• not covered by peritoneum/organs are bathed in amniotic fluid

Question 10

midline divisions of the abdomen (top to bottom)

Answer 10

epigastric
umbilical
suprapubic

Question 11

flank divisions of the abdomen (top to bottom)

Answer 11

hypochondriac
lumbar
inguinal

Question 12

what ribs cover the spleen

Answer 12

9-11

Question 13

what is the embryonic origin of GI organs?

Answer 13

splanchnopleuere (endoderm + mesoderm)

Question 14

differentiate between parenchyma and stroma of an organ - location, origin

Answer 14

parenchyma = epithelial cells; endoderm
stroma = connective tissue framework; mesoderm
Both from splanchnopleure

Question 15

foregut - artery supply, parasympathetic innervation, vertebral level, structures supplied

Answer 15

artery: celiac
parasym nerve: vagus
vertebral level: T12/L1
structures: stomach –> proximal dueodenum; liver, gallbladder, pancreas, spleen

Question 16

midgut - artery supply, parasympathetic innervation, vertebral level, structures supplied

Answer 16

artery: SMA
parasym nerve: vagus
vertebral level: L1
structures: distal dueodenum to proximal 2/3 of transverse colon

Question 17

hindgut - artery supply, parasympathetic innervation, vertebral level, structures supplied

Answer 17

artery: IMA
parasym nerve: pelvic
vertebral level: L3
structures: distal 1/3 of transverse colon –> upper portion of rectum

Question 18

where do arteries supplying GI structures branch from the abdominal aorta; name arteries top to bottom and vertebral level

Answer 18

Anteriorly
celiac trunk - T12
SMA - L1
IMA - L3

Question 19

name the SMA branches for the midgut (top to bottom)

Answer 19

(MRII)
middle colic (MC)
right colic (RC)
ileocolic (IC)
intestinal branches

Question 20

name the IMA branches for the hindgut (top to bottom)

Answer 20

(LSS)
left colic (LC)
sigmoid branches
superior rectal (SR)

Question 21

name the branches of the celiac trunk and what direction they come off (patient perspective)

Answer 21

1) splenic artery - left
2) left gastric artery - top
3) common hepatic - right

Question 22

what branch of the celiac trunk comes off to the left; what does it supply?

Answer 22

splenic artery - left; spleen + greater curve of stomach (short gastric arteries and left gastroepiploic)

Question 23

what branch of the celiac trunk comes off to the top? what does it supply?

Answer 23

left gastric artery - top; lesser curve of stomach

Question 24

what branch of the celiac trunk comes off to the right? what does it supply?

Answer 24

common hepatic - right; liver (hepatic proper + right gastric for lesser curve of stomach) + greater curve of stomach (gastroduodenal artery –> right gastroepiploic artery)

Question 25

Where do presynaptic parasympathetics synapse for the GI tract?

Answer 25

• Myenteric (auerbach’s) plexus - smooth muscle contraction in muscularis externa layer
• Submucosal (meissner’s) plexus - glandular secretion and muscularis mucosa

Question 26

spinal cord segments for visceral sensory innervation of the gut

Answer 26

T7-9 stomach (7 letters in stomach)
T10 appendix
L1 left colic flexure
L5 sigmoid colon

Question 27

3 anastomosis sites for venous portal-caval (portal vein first) and signs of portal obstruction/hypertension

Answer 27

1) left gastric-esophageal veins (esophageal varices)
2) para-umbilical vein - superficial epigastric veins (caput medussa on ab wall)
3) superior rectal veins - internal iliacs (hemorrhoids)

Question 28

pancreas is derived from what?

Answer 28

Foregut

2 buds - ventral and dorsal

Question 29

what does the ventral pancreas bud become?

Answer 29

part of pancreatic head and the uncinate process

main pancreatic duct

Question 30

what does the dorsal pancreas become?

Answer 30

body, tail, accessory pancreatic duct

Question 31

what is an annular pancreas

Answer 31

ventral bud encircles duodenum and causes narrowing

Question 32

what does the common bile duct (cystic duct from gall bladder + common hepatic duct from liver) lead to?

Answer 32

main pancreatic duct from the ventral bud

Question 33

where can gall stones can a back up of bile to pancreas leading to pancreatitis?

Answer 33

sphincter of oddi

major deuodenal papilla