The Peritoneum & Peritoneal Cavity Flashcards
What is the peritoneum?
Membrane lining abdominal cavity and encompassing some organs - Parietal peritoneum (around body wall) - Visceral peritoneum (around organs)
What is function of peritoneum?
It acts to support the viscera, and provides pathways for blood vessels and lymph to travel to and from the viscera.
What is the parietal peritoneum derived from?
Somatic mesoderm in the embryo.
What are both layers of peritoneum made up of?
Simple squamous epithelial cells called mesothelium
What is the parietal peritoneum sensitive to?
pressure, pain, laceration and temperature.
Why is pain from the parietal peritoneum well localised?
It receives the same somatic nerve supply as the region of the abdominal wall
What is the visceral peritoneum derived from?
Splanchnic mesoderm in the embryo
What is the visceral peritoneum sensitive to?
Only to stretch and chemical irritation
Describe pain from the visceral peritoneum
Poorly localised –> referred to areas of skin (dermatomes)
Describe the autonomic nerve supply of the visceral peritoneum?
The visceral peritoneum has the same autonomic nerve supply as the viscera it covers
What is the peritoneal cavity?
A potential space between the parietal and visceral peritoneum. It normally contains only a small amount of lubricating fluid
What can damage to the peritoneum lead to?
The resulting inflammation and repair may cause the formation of fibrous scar tissue. This can result in abnormal attachments between the visceral peritoneum of adjacent organs or between visceral and parietal peritoneum.
Such adhesions can result in pain and complications such as volvulus, when the intestine becomes twisted around an adhesion resulting in a bowel obstruction.
What are intraperitoneal organs?
Enveloped entirely by visceral peritoneum, which covers the organ both anteriorly and posteriorly. Examples include the stomach, liver and spleen.
What are retroperitoneal organs?
Not associated with visceral peritoneum; they are only covered in parietal peritoneum, and that peritoneum only covers their anterior surface.
What are 1ary retroperitoneal organs?
Developed and remain outside of the parietal peritoneum.
E.g. oesophagus, rectum and kidneys
What are 2ary retroperitoneal organs?
Were initially intraperitoneal, suspended by mesentery. Through the course of embryogenesis, they became retroperitoneal as their mesentery fused with the posterior abdominal wall. Thus, in adults, only their anterior surface is covered with peritoneum.
E.g. ascending and descending colon
SAD PUCKER: retroperitoneal organs
S - Suprarenal (adrenal) glands
A - Aorta/IVC
D - Duodenum (except proximal 2cm)
P - Pancreas U: Ureters C: Colon (ascending and descending) K: Kidneys E: (O)esophagus R: Rectum
What is a mesentery?
A double layer of visceral peritoneum that connects an intraperitoneal organ to (usually) the posterior abdominal wall
What is function of a mesentery?
It provides a pathway for nerves, blood vessels and lymphatics to travel from the body wall to the viscera.
What is the mesentery of the SI called? How does this differ from other mesenteries?
‘The mesentery’
Mesentery related to other parts of the GI is named according to the viscera it connects to; e.g the transverse and sigmoid mesocolons, the mesoappendix.
What are the omenta?
Sheets of visceral peritoneum that extend from the stomach and proximal part of the duodenum to other abdominal organs
What does the greater omentum consist of?
Four layers of visceral peritoneum
Where is the greater omentum found?
It descends from the greater curvature of the stomach and proximal part of the duodenum, then folds back up and attaches to the anterior surface of the transverse colon.
What does the lesser omentum consist of?
A double layer of visceral peritoneum:
- The hepatogastric ligament (the flat, broad sheet)
- The hepatoduodenal ligament (the free edge, containing the portal triad)
What is a peritoneal ligament?
A double fold of peritoneum that connects viscera together or connects viscera to the abdominal wall.
An example is the hepatogastric ligament, a portion of the lesser omentum, which connects the liver to the stomach.
Where is pain from the:
- Foregut
- Midgut
- Hindgut
structures referred to?
- Epigastric region
- Umbilical region
- Pubic region
What are the foregut structures?
Oesophagus, stomach, pancreas, liver, gallbladder and the duodenum (proximal to the entrance of the common bile duct).
What can pain in retroperitoneal organs (e.g. kidney, pancreas) present as?
Back pain
What can irritation of the diaphragm (e.g. as a result of inflammation of the liver, gallbladder or duodenum) result in?
Shoulder tip pain
Where is pain from the appendix (appendicitis) initially referred to?
Initially pain from the appendix (midgut structure) and its visceral peritoneum is referred to the umbilical region
As the appendix becomes increasingly inflamed, where is pain referred to?
It irritates the parietal peritoneum, causing the pain to localise to the right lower quadrant.
What is the peritoneal cavity?
A potential space between the parietal and visceral peritoneum.
What does the peritoneal cavity normally contain?
A thin film of peritoneal fluid, which consists of water, electrolytes, leukocytes and antibodies
What is purpose of peritoneal fluid?
This fluid acts as a lubricant, enabling free movement of the abdominal viscera, and the antibodies in the fluid fight infection.
Why is the peritoneal cavity referred to as a potential space?
Because excess fluid can accumulate in it, resulting in the clinical condition of ascites
What can the peritoneal cavity be divided into?
The greater and lesser peritoneal sacs
What is the greater sac?
Comprises the majority of the peritoneal cavity
What is the greater sac divided into and by what?
It is further divided into two compartments by the mesentery of the transverse colon (known as the transverse mesocolon):
- Supracolic compartment
- Infracolic compartment
Where does the supracolic compartment lie? What does it contain?
Lies above the transverse mesocolon and contains the stomach, liver and spleen.
Where does the infracolic compartment lie? What does it contain?
Lies below the transverse mesocolon and contains the small intestine, ascending and descending colon.
What can the infracolic compartment be further divided into? By what?
Left and right infracolic spaces by the mesentery of the small intestine.
How are the supracolic and infracolic compartments connected?
By the paracolic gutters
Where do the paracolic gutters lie?
Between the posterolateral abdominal wall and the lateral aspect of the ascending or descending colon
What are the subphrenic recesses?
Potential spaces in the supracolic compartment of the greater sac
Where are the subphrenic recesses located?
Between the diaphragm and the liver
What are the subphrenic recesses separated into?
There are left and right subphrenic spaces, separated by the falciform ligament of the liver.
What are subphrenic abscesses?
Refer to an accumulation of pus in the left or right subphrenic space.
Where are subphrenic abscesses more common?
On the right side due to the increased frequency of appendicitis and ruptured duodenal ulcers (pus from the appendix can track up to the subphrenic space via the right paracolic gutter).
Where is the lesser sac located?
Lies posteriorly to the stomach and lesser omentum
Function of the lesser sac?
It allows the stomach to move freely against the structures posterior and inferior to it.
How is the lesser and greater sac connected?
By the epiploic foramen
Where is the epiploic foramen?
Posterior to the free edge of the lesser omentum (the hepatoduodenal ligament).
In males, what is the rectovesical pouch?
A double folding of peritoneum located between the rectum and the bladder.
Is the peritoneal cavity completely closed in males?
Yes
What are the 2 areas of notes in the female peritoneal cavity?
- Rectouterine pouch
2. Vesicouterine pouch
What is the rectouterine pouch?
Double folding of the peritoneum between the rectum and the posterior wall of the uterus.
What is the vesicouterine pouch?
Double folding of peritoneum between the anterior surface of the uterus and the bladder.
Is the peritoneal cavity completely closed in females?
No - the uterine tubes open into the peritoneal cavity, providing a potential pathway between the female genital tract and the abdominal cavity.
Clinically, this means that infections of the vagina, uterus, or uterine tubes may result in infection and inflammation of the peritoneum (peritonitis).
Why is passage of infectious material into the peritoneum rare?
Due to the presence of a mucous plug in the external os (opening) of the uterus which prevents the passage of pathogens but allows sperm to enter the uterus.
What is culdocentesis?
The extraction of fluid from the rectouterine pouch through a needle inserted through the posterior fornix of the vagina.
What is culdocentesis used for?
It can be used to extract fluid from the peritoneal cavity or to drain a pelvic abscess in the rectouterine pouch
What is paracentesis?
A procedure used to drain fluid from the peritoneal cavity. A needle is inserted through the anterolateral abdominal wall into the peritoneal cavity. The needle must be inserted superior to the urinary bladder and the clinician must take care to avoid the inferior epigastric artery.
What is paracentesis used for?
It is used to drain ascitic fluid, diagnose the cause of ascites and to check for certain types of cancer which may metastasise via the peritoneum, e.g. liver cancer.
What is peritonitis?
Infection and inflammation of the peritoneum. It can occur as a result of bacterial contamination during a laparotomy (open surgical incision of the peritoneum) or it can occur secondary to an infection elsewhere in the GI tract, for example a ruptured appendix, acute pancreatitis or a gastric ulcer eroding through the wall of the stomach.
How can infection from appendicitis travel to lesser sac?
Appendix located in right iliac fossa in infracolic compartment
Infracolic and supracolic compartments connected via paracolic gutters
Greater and lesser sacs connected via epiploic foramen
Right paracolic gutter –> hepatorenal recess (recess in supracolic compartment) –> epiploic foramen
