Wk 3 - Anatomy: Jejunum, Ileum and Peritoneum Flashcards
What structures are derived from the midgut?
Midgut derived structures include the duodenum distal to the ampulla of Vater, the jejunum, ileum, cecum, ascending colon, and foremost two-thirds of the transverse colon.
Unlike the foregut and hindgut, the midgut remains connected to the yolk sac via the…
Vitelline duct (connects midgut to yolk sac)
What is Meckel diverticulum?
- Meckel diverticulum is a congenital intestinal diverticulum due to fibrous degeneration of the umbilical end of the omphalomesenteric (vitelline) duct that occurs around the distal ileum.
- ie Results as a failure of the vitelline duct to obliterate during the fifth week of fetal development.
- It is considered the most common structural congenital anomaly of the gastrointestinal tract.
Describe physiological umbilical herniation of the embryo during gut development.
In the 6th week of embryological development, the rapidly growing liver and gut outgrow the abdominal cavity and the intestinal loop is forced into the umbilical cord (herniates through the umbilical ring).
What portion of the intestinal loop (in the embryo) forms the distal duodenum, jejunum and proximal ileum?
Cephalic limb of the loop
What portion of the intestinal loop (in the embryo) forms the distal ileum, caecum, appendix, ascending colon and proximal 2/3rds of the transverse colon?
Caudal limb of the loop
The development of the midgut continues outside of the abdominal cavity until roughly week ____ of development where the ____ return to the abdominal cavity via ____.
The development of the midgut continues outside of the abdominal cavity until roughly week TEN of development where the intestinal loops return to the abdominal cavity via rotation.
During retraction of the herniated loops, the ____ (cephalic limb/caecal bud) re-enters first, to the left while the ____ (cephalic limb/caecal bud) re-enters last, initially to right upper quadrant.
During retraction of the herniated loops, the cephalic limb re-enters first, to the left while the caecal bud re-enters last, initially to right upper quadrant.
The ventral mesentery of the embryo becomes the…
- Falciform ligament
- Lesser omentum
The dorsal mesentery of the embryo becomes the…
- Splenorenal ligament
- Gastrosplenic ligament
- Greater omentum
What are mesenteries? and what is their function?
Mesenteries are double layers of peritoneum in the abdominal cavity and are continuations of the visceral and parietal peritoneum with the serous membranes adhered back to back so that the outer mesothelium secretes serous fluid into the peritoneal cavity. This decreases the friction between the adjacent visceral surfaces and allows some movement of the organs that occur during digestion.
How many mesenteries are there in a fully formed abdominal cavity? Name them.
In the fully formed abdominal cavity, mesenteries are found dorsally and adhere the viscera to the posterior wall. There are three mesenteries, all named after their organ attachments in the abdominal cavity, as follows:
- the mesentery of the small intestine or mesentery proper,
- transverse mesocolon
- sigmoid mesocolon
What is the mesentery proper?
- The mesentery of the small intestine is a large and broad fan-shaped mesentery.
- It is attached to the jejunum and ileum of the small intestine, connecting them to the posterior abdominal wall.
- The root extends from duodenojejunal flexure to ileocaecal junction.
The peritoneal cavity can be divided into…
- Greater and lesser sacs.
- The greater sac comprises the majority of the peritoneal cavity.
- The lesser sac (also known as the omental bursa) is smaller and lies posterior to the stomach and lesser omentum.
The lesser sac communicates with the greater sac via…
The epiploic foramen