2. The gut and peritoneal cavity Flashcards
What type of epithelium is the peritoneum?
Simple squamous epithelium: mesothelium
Peritoneum
continuous membrane lining the abdominal cavity consisting of mesothelial layer supported by a layer of connective tissue
What is contained in the peritoneal cavity?
Nothing
It is a potential space
There is only a small amount of fluid
How does the peritoneum relate to viscera of the abdomen?
Intra-abdominal organs are suspended in peritoneal reflections (mesenteries)
Which germ layers does the gut tube develop from?
Endoderm and splanchnic mesoderm
Which mesenteries suspend the different parts of the gut tube?
Entire gut tube is suspended by dorsal mesentery
Foregut is ALSO suspended by ventral mesentery
Mesenteries
peritoneal folds attaching viscera to the abdominal wall
What do the peritoneal folds act as a conduit for?
Nerves
Blood vessels
Lymphatics
Visceral and parietal peritoneum
VISCERAL: covering the suspended organs
PARIETAL: lines the abdominal wall.
What is the difference between intraperitoneal and retroperitoneal?
Intraperitoneal: surrounded by peritoneum
Retroperitoneal: behind the peritoneum, not totally surrounded by peritoneum.
State 3 viscera that are secondarily retroperitoneal.
Duodenum (except the 1st part)
Pancreas (tail is intraperitoneal)
Colon (ascending and descending only)
State 5 viscera that were retroperitoneal from the start.
Kidneys Great vessels Adrenal glands Oesophagus Rectum
What are secondary retroperitoneal organs?
Organs that originally had a mesentery, then became secondarily retroperitoneal when the mesentery fused with the body wall
What are the 3 divisions of the gut tube and what defines their borders?
Foregut: distal 1/3 of the oesophagus to just inferior of major duodenal papilla (2nd part of duodenum: at the entrance of the bile duct)
Midgut: 2nd part of the duodenum to 2/3 along the transverse colon
Hindgut: Distal 1/3 of transverse colon to the rectum
What does the ventral mesentery split into?
Falciform ligament
Lesser omentum
How is the lesser sac (omental bursa) formed?
Liver moves right
Stomach and spleen move left with the dorsal mesentery thus cutting off a space behind the stomach= the lesser sac
What is the lesser omentum?
Fold of peritoneum between the liver and the lesser curvature of the stomach
What is the greater omentum?
Lower part of the dorsal foregut mesentery extends down form the greater curvature of the stomach as the greater omentum.
Lies like an apron in front of the intestines.
Why does the lesser omentum have a lower free border and what opening does that form?
Because it is formed by the ventral foregut mesentery, which ends at the start of the midgut.
Opening to the omental bursa is called the epiploic foramen.
What vessels run within the lesser omentum near its free edge?
Hepatic portal vein
Hepatic artery
Bile duct
Describe how the abdomen is divided into different compartments.
Transverse mesocolon divides the abdomen into supracolic and infracolic compartments. Infracolic compartment is further divided by the mesentery of the small intestine (from the duodeno-jejunal flexure to the ileo-caecal valve) - dividing the infracolic compartment into right and left infracolic compartments.
There are also gutters running along the lateral sides of the ascending and descending colon called the right and left paracolic gutter.