peritoneum Flashcards
What is the peritoneum?
A continuous, slippery serous membrane consisting of the parietal and visceral layers.
What are the two layers of the peritoneum?
Parietal peritoneum: Lines the internal surface of the abdominopelvic cavity.
Visceral peritoneum: Covers the internal organs like the stomach and intestines.
What type of cells make up the peritoneum?
Simple squamous epithelial cells (mesothelium).
What is the peritoneal cavity?
A potential space between the parietal and visceral peritoneum containing peritoneal fluid.
What is the function of peritoneal fluid?
Lubricates peritoneal surfaces, allowing frictionless movement of viscera (important for digestion).
How does the peritoneal cavity differ between males and females?
Males: Completely closed.
Females: Open to the external environment via the uterine tubes, uterine cavity, and vagina.
Why is the peritoneal cavity’s openness in females clinically significant?
It provides a potential infection pathway from the external environment.
How is the embryonic gut tube connected to the body wall?
By the ventral and dorsal mesenteries.
What happens to the ventral and dorsal mesenteries during development?
Ventral mesentery mostly disappears, except for the falciform ligament (connecting to the liver).
Dorsal mesentery remains and suspends the gut tube from the posterior abdominal wall.
What important structures pass through the dorsal mesentery?
The arteries that supply the gut tube.
What are the three main arteries supplying the gut tube?
Coeliac trunk → Foregut
Superior mesenteric artery → Midgut
Inferior mesenteric artery → Hindgut
What are the two mesoderm layers related to the gut tube?
Somatic mesoderm (body wall)
Splanchnic mesoderm (gut tube)
What is a mesentery?
A double layer of peritoneum formed by the invagination of an organ, where the visceral peritoneum becomes continuous with the parietal peritoneum.
What is the mesentery commonly referred to?
“The mesentery,” specifically referring to the small intestine mesentery.
What are examples of mesenteries in the body?
Transverse mesocolon (attaching the transverse colon)
Sigmoid mesocolon (attaching the sigmoid colon)
Mesoappendix (supporting the appendix)
Mesogastrium (supporting the stomach)
What is an omentum?
A double-layered peritoneal fold that extends from the stomach and proximal duodenum to adjacent abdominal organs.
What is the greater omentum and where does it attach?
A four-layered peritoneal fold derived from the dorsal mesogastrium.
Hangs like an apron from the greater curvature of the stomach and proximal duodenum.
Descends and folds back to attach to the anterior surface of the transverse colon.
What is the lesser omentum and where does it attach?
A double-layered peritoneal fold derived from the ventral mesogastrium.
Connects the lesser curvature of the stomach and proximal duodenum to the liver.
What is a peritoneal ligament?
A double-layered peritoneum that connects an organ to another organ or to the abdominal wall.
What 3 ligaments connect the liver, and to what structures?
Falciform ligament → Anterior abdominal wall
Hepatogastric ligament → Stomach (part of the lesser omentum)
Hepatoduodenal ligament → Duodenum (part of the lesser omentum)
Which ligament connects the stomach to the spleen?
Gastrosplenic ligament
What are bare areas in intraperitoneal organs?
Regions not covered by visceral peritoneum, allowing neurovascular structures to enter or exit the organ.
Why do bare areas exist?
To permit vascular and nerve connections without being enclosed by peritoneum.
Where is a well-known bare area found?
On the posterior surface of the liver.
Which ligaments are attached to the spleen?
The gastrosplenic ligament and the splenorenal ligament.
What is a peritoneal fold?
A reflection of peritoneum raised by underlying blood vessels, ducts, or ligaments formed by obliterated fetal vessels.
What is the median umbilical fold, and what does it cover?
Extends from the urinary bladder to the umbilicus.
Covers the median umbilical ligament, a fibrous remnant of the urachus (which connected the fetal bladder to the umbilicus).
How many medial umbilical folds are there, and what do they cover?
Two medial umbilical folds.
Cover the medial umbilical ligaments, which are formed by the occluded umbilical arteries.
How many lateral umbilical folds are there, and what do they cover?
Two lateral umbilical folds.
Cover the inferior epigastric vessels (these can bleed if cut).
How is the peritoneal cavity divided?
Into the greater sac and lesser sac due to stomach development.
What causes the formation of the lesser and greater curvatures?
Unequal growth rates in different regions of the stomach wall.
How does the stomach rotate along the longitudinal axis?
90° clockwise rotation, causing:
Left side to face anteriorly.
Right side to face posteriorly.
How does the stomach rotate along the anteroposterior axis?
Cephalic end moves left and downward.
Caudal end moves right and upward.
How does liver growth affect organ positioning?
The liver grows faster on the right, pushing other organs to the left (shown in diagram B to C)
How does stomach rotation contribute to organ movement?
The rotation of the stomach helps facilitate the shift of organs caused by liver expansion.
How is the lesser sac (omental bursa) formed?
As the liver moves to the right, the right side of the peritoneal cavity is pushed posterior to the stomach and lesser omentum, forming the lesser sac.
What are the two main subdivisions of the peritoneal cavity?
Greater sac: Main, larger part of the peritoneal cavity.
Lesser sac (omental bursa): Space behind the stomach and lesser omentum.
Which structures surround the lesser sac?
Anteriorly: Stomach, lesser omentum.
Posteriorly: Pancreas.
Laterally: Spleen.
What are the two recesses of the omental bursa?
Superior recess: Limited superiorly by the diaphragm.
Inferior recess: Located between the superior parts of the layers of the greater omentum.
How does the omental bursa connect to the greater peritoneal cavity?
Through the epiploic foramen (foramen of Winslow).
What is the epiploic (omental) foramen?
The passage that allows communication between the greater and lesser sacs of the peritoneal cavity.
Where is the epiploic foramen located?
Posterior to the free edge of the lesser omentum, specifically the hepatoduodenal ligament.
What are the four boundaries of the epiploic foramen?
Anterior: Hepatoduodenal ligament (containing the portal triad: hepatic artery, portal vein, bile duct).
Posterior: Inferior vena cava (IVC).
Superior: Liver.
Inferior: First part of the duodenum.
How is the greater sac divided?
By the transverse mesocolon into:
Supracolic compartment (above the transverse mesocolon).
Infracolic compartment (below the transverse mesocolon)
How is the infracolic compartment divided?
Into right and left colic spaces by the mesentery of the small intestine.
How do the supracolic and infracolic compartments communicate?
Through the paracolic gutters, which are grooves between the lateral aspects of the ascending and descending colon and the posterolateral abdominal wall.
What is the peritoneal cavity, and how is it related to the extraperitoneal space?
The peritoneal cavity is a closed cavity lined by peritoneum.
It is surrounded by the extraperitoneal cavity (appears as a narrow slit).
Only the posterior (retroperitoneal) and inferior (extraperitoneal pelvic) portions contain true spaces with organs.
What is the difference between intraperitoneal and retroperitoneal organs?
Intraperitoneal: Completely surrounded by visceral peritoneum.
Retroperitoneal: Lie against the posterior body wall and are only covered on their anterior surface by peritoneum.
What is the difference between primary and secondary retroperitoneal organs?
Primary retroperitoneal organs: Were retroperitoneal from the start of development.
Secondary retroperitoneal organs: Were initially intraperitoneal but migrated posteriorly, fusing with the parietal peritoneum.
Name primary retroperitoneal organs.
Kidneys
Suprarenal (adrenal) glands
Name 3 secondary retroperitoneal organs.
Ascending colon
Descending colon
pancreas
How do secondary retroperitoneal organs become retroperitoneal?
They start as intraperitoneal organs.
Over time, they shift posteriorly and fuse with the parietal peritoneum, becoming retroperitoneal.
