Gut Rotation

Question 1

Dorsal mesentery of stomach forms?

Answer 1

Greater omentum

Spleen

Question 2

Ventral mesentery of stomach forms?

Answer 2

(Forms two parts w/ Liver in between)

Lesser omentum

Falciform ligament

Question 3

Lesser omentum contains what three important vessels?

Answer 3

Proper hepatic A

Hepatic portal v

Common bile duct

Question 4

Rest of the gut tube below the stomach contains only what type of mesentery?

Answer 4

Dorsal mesentary

Called “meso___”

ex: mesoduodenum

Question 5

Organization of early gut tube

Answer 5

Everything in midline

Peritoneal cavity single below stomach

Divided into right and left halves at stomach

Question 6

Right half of early gut tube at stomach level info

Answer 6

Gets much smaller-lesser peritoneal sac

Accessible in adults only via epiploic foramen of winslow

Question 7

Left half of early gut tube at stomach level info

Answer 7

Remains continuous w/ rest of peritoneal cavity

Called peritoneal sac

Question 8

First gut rotation

Answer 8

90 degrees around vertical axis

Mesenteries from dorsal go left, ventral go right

Liver ends up on right side

Question 9

Second gut rotation

Answer 9

90 degrees along horizontal axis

Stomach now in adult location

Greater omentum @ greater curvature of stomach grows to cover intestines

Lesser omentum @ lesser curvature of stomach is very thin except hepatoduodenal part

Question 10

What does the midgut loop form?

Answer 10

Small intestine

Ascending and Transverse colon

Question 11

What vessel runs down center of loop?

Answer 11

Superior mesenteric artery (SMA)

Question 12

What connects yolk sac to apex of midgut loop?

Answer 12

Vitelline duct

(Forms Meckel’s diverticulum within last 3’ of ileum)

Question 13

Mid gut loop rotation

Answer 13

270 degrees CW

Question 14

What happens to duodenum during midgut loop rotation?

Answer 14

Lies dorsal to SMA

All but first part are secondarily retroperitoneal

Question 15

What does it mean to be secondarily retroperitoneal?

Answer 15

Mesentery is “lost” and fuses to post. wall of abdomin

Question 16

What happens to colon during midgut loop rotation?

Answer 16

loops around SI from right to left

Question 17

What all becomes secondarily retroperitoneal?

Answer 17

All but first part of duodenum

Ascending and Descending colon

Question 18

What happens to transverse colon during midgut loop rotation?

Answer 18

Hangs onto its mesentery-transverse mesocolon

Trans. mesocolon covered by greater omentum and fuses to its deep surface

Question 19

Where does spleen form?

Answer 19

Dorsal mesentery of stomach

Parts of dorsal mesentery are thickened ligaments that attach to spleen

(lienophrenic)

Question 20

How does celiac trunk form?

Answer 20

Travel through dorsal mesentery on either side of stomach

Splenic branch-spleen, stomach

Common hepatic branch-liver, stomach, duodenum, pancreas

Left gastric branch-lesser curvature of stomach

Question 21

How does pancreas form?

Answer 21

As two outgrowths of duodenum

Coalesce (but remain separate ducts) in dorsal mesentary

This mesentery fuses with parietal peritoneum so appears retroperitoneal