GUT DEV'T.

Question 1

All of the following organs have what in common?
(Stomach, Liver, gallbladder, spleen, 1st part of duodenum, tail of pancreas, jejunum, ileum, appendix, proximal 2/3 transverse colon, sigmoid colon)

Answer 1

Major Peritoneal Organs

Question 2

All of the following organs have what in common?

Kidney, adrenal gland, ureter, aorta, inferior vena cava, lower rectum, anal canal

Answer 2

Primary Retroperitoneal Organs

Question 3

All of the following organs have what in common?

Parts 2-4 of duodenum, most of pancreas, ascending colon, descending colon, upper rectum

Answer 3

Secondary Retroperitoneal Organs

Question 4

Define secondary retroperitoneal organ.

Answer 4

An organ that started as a peritoneal organ but became PARTIALLY covered by parietal peritoneum

Question 5

What is the role of the mesentery?

Answer 5

A double layer of vascularized tissue that divides parietal peritoneum from visceral peritoneum. It contains dorsal and ventral arteries that supply ALL peritoneal organs.

Question 6

Explain the significance of the Hepatic Diverticulum.

Answer 6

This is an evagination of the ventral wall of the gut tube into a WIDER ventral mesentery during embryonic gut development.

Question 7

The tail of the pancreas is a ________ organ, whereas the head of the pancreas is a ________ organ. Which part of the pancreas is more anterior?

Answer 7

Tail is peritoneal organ;
Head is secondary retroperitoneal organ;
The tail is more anterior to the head of the pancreas.

Question 8

What three structures are contained in the hepatoduodenal ligament?

Answer 8

The portal triad composed of proper hepatic artery (left), common bile duct (right) and portal vein (posterior to both).

Question 9

What artery runs along the lesser curvature of the stomach? What of the greater curvature?

Answer 9

Lesser stomach curvature - Left gastric artery
Greater stomach curvature - mainly supplied by the Right gastro-omental artery; partly by the left gastric-omental artery

Question 10

The lesser omentum is made up of what two structures?

Answer 10

The hepatoduodenal ligament (containing the portal triad) and the translucent hepatogastric ligament.

Question 11

Describe the rotation of the midgut

Answer 11

The midgut rotates 270 degrees across the horizontal (anteroposterial) plane of the SMA, if viewed from the front of the body

Question 12

Describe the cause and effect of Annular Pancreas.

Answer 12

Some of the pancreas constricts the 2nd part of the duodenum as a result of a defective 180 degree rotation during embryological development.

Question 13

The pancreas used to have 2 locations in the gut. The ventral portion rotated _____ degrees to fuse with the dorsal part. The dorsal part has the _____ duct whereas the ventral part has the _____ duct, which fuses with the common bile duct to empty via the ________ __ _____.

Answer 13

Ventral pancreas 180 degree rotation;
Dorsal = minor duct, ventral = major duct;
Ampulla of Vater drains into the 2nd part of duodenum.

Question 14

The spleen is suspended by 2 ligaments. The _____ ligament connects the spleen to the stomach and the _______ ligament has the tortuous splenic artery coursing within it.

Answer 14

Gastrosplenic ligament;

Splenorenal ligament.

Question 15

How does Omphalocele differ form Gastroschisis?

Answer 15

Omphalocele is caused by a defect in the retraction of the gut in which a portion of the gut is trapped outside the body within the umbilical cord.
Gastroschisis is caused by a defect in the lateral folds of the body wall to fuse, leading to non-function intestines that were EXPOSED to the amniotic fluid.

Question 16

Secondary retroperitoneal organs are ALWAYS _ ______ of primary retroperitoneal organs. Name at least 4 organs that are secondarily retroperitoneal.

Answer 16

In front of primary retroperitoneal organs;

Most of duodenum, most of pancreas, ascending and descending colon, upper rectum

Question 17

During weeks 3-4 in the formation of the embryonic gut tube, the _________ plug is supposed to form and apoptosis in the center to form ______.

Answer 17

Epithelial plug;

lumen

Question 18

A defect in the apoptosis of the epithelial plug can lead to duodenal _____ or ______.

Answer 18

Duodenal stenosis - bilus vomit from little apoptosis

Duodenal atresia - non-bilus vomit from no apoptosis

Question 19

Describe what a Vitelline Fistula is and how it differs from Ileal (Meckel’s) Diverticulum.

Answer 19

A vitelline fistula comes from the failure to fuse the vitelline duct, where inside contents are EXPOSED to the outside world. An ileal diverticulum is a BLIND-END remnant of the vitelline duct that forms from a failure of the vitelline duct to completely fuse.

Question 20

Describe the rotation of the foregut and its effects on position of organs. Provide a few examples.

Answer 20

The foregut rotates 90 degrees clockwise along the axis of the gut tube. This positions organs that were once ventral organs on the right side of the body and dorsal organs on the left side.
For example, the liver and lesser omentum that were ventral are now on the right side and the dorsal spleen is on the left side of the body.

Question 21

How did foregut rotation affect the esophagus?

Answer 21

The esophagus also rotated since it is attached to the stomach, in which the right vagus covers the posterior side and the left vagal plexus covers the anterior side.

Question 22

Describe the Foramen of Winslow

Answer 22

Winslow’s foramen, also known as the Epiploic foramen, is located on the right side of the body as an opening between the greater sac and lesser sac. It lies under quadrate lobe of the liver.

Question 23

Describe the features of the quadrate and caudate lobe.

Answer 23

The quadrate lobe is bordered by the gallbladder and the falciform ligament of the liver. Whereas the caudate lobe is located superior to the porta hepatis and looks like a smaller, fin-shaped lobe.
Both the quadrate and caudate lobe are functionally on the left lobe BUT anatomically on the right liver lobe.

Question 24

Describe the rotation of the midgut and its effect on the position of organs. Provide a few examples of its effect.

Answer 24

Midgut rotation moves the intestines out into the umbilical cord to lengthen, rotates it 270 degrees counter-clockwise along the axis of the SMA and normally retracts it back into the body right after.
This positioned the proximal jejunum on the LUQ and the distal ileum on the RLQ.

Question 25

Although Gastroschisis ends up with a portion of non-functional intestines, why does omphalocele have a higher mortality rate?

Answer 25

Omphalocele is associated with other genetic defects such as malformation of the heart and kidneys. This explains the higher risk of mortality.

Question 26

The Left Colic Artery was within the _________ in the embryo but later became ______ ________ in the adult.

Answer 26

Mesentery;

Secondary Retroperitoneal