Anatomy Lecture 27_Development of Abdominal Organs Flashcards
What are the 4 developmental dorsal Mesenterys?
1) Dorsal Mesogastrium
2) Dorsal Mesodeuodnum
3) Mesentery Proper (this contains most of the small intestine)
4) Dorsal Mesocolon
What is Esophageal atresia?
It is when the esophagus fails to Recanalize during week 8 of development. This leaves the espohagus in two parts with the proximal portion ending in a blind sac. This prevents the fetus from swallowing amniotic fluid which is essential for gut development
Describe rotation of the developing stomach
1) the stomach rotates 90 degrees around the longitudinal axis. The side that was origionaly the posterior wall becomes the left wall and grows at a greater rate giving rise to the greater curvature of the stomach.
2) The stomach then rotates away from being totally logitudinal and tips the pyloric region to the right and the cardia to the left.
What does the 90 degree logintudinal rotation of the stomach create?
It pulls the mesentary to the left and creates the lesser omental sac (omental bursa)
What does the vertical rotation of the stomach give rise to?
As the stomach tips it takes the mesentery with it and this gives rise to the greater omentum.
What does the spleen develop from?
It develops at week 5 of gestation within the dorsal mesogastrium from lateral plate mesoderm
What two ligaments hold the spleen intraperatonial?
Fused to left kidney by splenorenal lig., stomach by gastrosplenic lig.
What does the Ventral Mesogastrium turn into?
falciform ligament & lesser omentum
Where do the two buds of the Pancreas arise?
Dorsal (dorsal mesogastrium) & Ventral (ventral mesogastrium). The dorsal bud is basically coming off the proximal duodenum. The ventral bud is coming off the bile duct.
What causes the two buds of the Pancreas to fuse?
- Rotation of duodenum to right moves ventral bud dorsally
- Ventral bud fuses with dorsal bud
- Forms uncinate process & (part) head of pancreas
- Dorsal bud forms the rest
What gives rise to the Main pancreatic duct?
distal dorsal duct and entire ventral duct
What gives rise to the Accessory pancreatic duct?
proximal dorsal duct (sometime this structure is not present in adults)
Describe an Annular Pancreas
An Annular Pancreas results when the ventral bud bifercates and fuses around the duodenum. This constricts the duodenum and will likely result in projectile vomiting. Typically this occurs above the pancreatic duct. This results in no billiouse vomit
Describe the formation of the midgut
The mesnentery proper contains two contains two loops, the cephalic limb (gives rise to the small intestine and is located superior to the SMA) and the caudal limb (gives rise to the large intestine and is inferior to the SMA)
1) The cephalic limb experiences rapid growth and coils, the caudal limb does not
2) The loops rotate 90 degrees placing the cephalic limb on the right. The intestine then herniates into the umbilical cord (week 6)
3) At week 10 the intestinal loops return to the abdominal cavity. They then rotate 180 degrees more. This places the cephalic limb (small intestine) on the left and the caudal limb (large intestine) on the right
Which structures are retroperitoneal?
Duodenum, Pancreas, asending and desending colon