128b - GI Development and Organization

Question 1

Which embryologic structure persists to form Meckel’s Diverticulum?

Answer 1

Yolk Sac (and the Vitelline Duct)

Question 2

What is a primarily retroperitoneal organ?

Which organs are primarily retroperitoneal? (6)

Answer 2

Organs that start growing in the body wall behind the parietal peritoneum and remain there

• IVC
• Vagina
• Kidneys
• Aorta
• Rectum
• Bladder

If you were stuck outside all day you would need energy - maybe IV KARBs would help

Question 3

In which part of the GI tract does a Meckel diverticulum form?

Answer 3

Terminal ileum

Question 4

Which embryologic structure separates the pericardial/thoracic cavity from the peritoneal cavity?

Answer 4

Septum transversum

Question 5

Which structure connects the lesser sac and the greater sac (peritoneal cavity)?

Answer 5

Epiploic foramen (of Winslow) aka Omental foramen

(Right behind the hepatoduodenal ligament)

Question 6

Which structures arise from the ventral mesogastrium? (aka ventral mesentary)

Answer 6

• Falciform ligament
• Lesser omentum
  
  • Hepatogastric ligamnet
  • Hepatoduodenal ligament
• Coronary ligament

Question 7

If you were inside the lesser peritoneal sac or its entryway through the epiploic foramen, which of the following mesenteries would you be unable to touch?

A. Splenorenal

B. Prenicocllic

C. Hepatoduodenal

D. Gastrosplenic

E. Hepatogastric

Answer 7

B. Prenicocllic

Question 8

What is the location of the junction of the abdominal foregut and midgut?

Answer 8

Middle of the duodenum

• Foregut
  
  • End of the esophagus through the proximal 1/2 of the duodenum
• Midgut
  
  • Distal duodenum through through the proximal 2/3 of the transverse colon
• Hindgut
  
  • Distal 1/3 of the transverse colon through the pectinate line

Question 9

Which congenital hernia is the result of an abdominal wall defect?

Answer 9

Gastroschisis

Question 10

What birth defect arises from failure of the midgut to return to the abdominal cavity from the umbilical cord?

When is it supposed to return?

Answer 10

Omphaocele (congential umbilical hernia, covered by amnion)

Midgut should return by week 10

Failure = omphalocele

Question 11

Which mesenteries form the lesser omentum?

Answer 11

Hepatogastric + hepatoduodenal ligaments

Ventral mesogastrium/mesentery (and lesser omentum) does not have any splenic ligament or structures.

Dorsal mesogastrium/mesentery (and greater omentum) does not have any hepatic ligament or structures

Question 12

Which parts of the colon are peritonealized?

Which are retroperitoneal?

Answer 12

• Peritonealized
  
  • Cecum, transverse colon, sigmoid colon -> upper 1/3 of rectum
• Retroperitoneal:
  
  • Ascending colon, descending colon

Question 13

Where in the abdominal cavity is the lesser sac located? (general)

Answer 13

The lesser sac is the “space behind the stomach”

It will grow down to cover the small intestines

Communicates wtih the greater sac through the epiploic/omental foramen (behind the hepatoduodenal ligament)

Question 14

Which major artery supplies the midgut?

Answer 14

Superior mesenteric artery

Question 15

What is a secondarily retroperitoneal organ?

Which organs are secondarily retroperitoneal? (4)

Answer 15

Organs that begin growing in the mesentery, but get pushed against the body wall (and stick there) by the growth of peritoneal organs, so they look retroperitoneal

• Pancreas
• Ascending colon
• Descending colon
• Duodenum

They’re pushed agsinst the body wall, covering it like a PADD

Question 16

Which anatomic features that distinguish large intestine from small intestine?

Answer 16

Teniae coli and Haustra in the large intestine

Question 17

What is a peritonealized organ?

Which organs are peritonealized? (9)

Answer 17

Organs that develop in mesenteries and hang out inside of the peritoneum

• Stomach
• Liver
• Uterus
• Gallbladder
• Spleen
• Intestines (except duodenum)
• Cecum
• Transverse colon
• Sigmoid colon -> upper 1/3 of rectum

Imagine you are a super cool slug hanging out in the peritoneal space with all the super cool organs - you’re just vibing and people are like “oh sweet, the SLUG SIcTS” (Think of the C as silent)

Question 18

Which major artery supplies the hindgut?

Answer 18

Inferior mesenteric artery

Question 19

Which major artery supplies the midgut?

Answer 19

Superior mesenteric artery

Question 20

Which major artery supplies the foregut?

Answer 20

Celiac trunk

Question 21

The ligamentum teres is a remnant of which embryologic structure?

Answer 21

Umbilical vein

Question 22

Which ligament attaches the liver to the body wall?

Answer 22

Falciform ligament

Question 23

Which of the following organs is secondarily retroperitoneal?

A. Duodenum
B. Transverse colon
C. Spleen
D. Superior mesenteric artery
E. Kidney

Answer 23

A. Duodenum

• Transverse colon and spleen have mesenteries (they are intra-peritoneal)
• Kidneys are primarily retroperitoneal

Remember PADD (pancreas, ascending colon, descending colon, duodenum)

Question 24

Which structures arise from the dorsal mesogastrium?

Answer 24

• Greater omentum
• Gastrosplenic ligament
• Splenorenal ligament

Ventral mesogastrium/mesentery (and lesser omentum) does not have any splenic ligament or structures.

Dorsal mesogastrium/mesentery (and greater omentum) does not have any hepatic ligament or structures