Peritoneal anatomy Flashcards
What is the peritoneum?
A continuous membrane which lines the abdominal cavity and covers the abdominal organs.
What does the peritoneum provide?
Pathways for blood vessels and lymph to travel to and from the viscera.
Which 2 layers form the peritoneum?
The partietal and visceral peritoneum.
What cells are the peritoneal and visceral peritoneum made up of?
Simple squamous epithelial cells (mesothelium)
What does the parietal peritoneum line?
Internal surface of the abdominopelvic wall.
Where is the parietal peritoneum derived from?
Somatic mesoderm.
Why is pain from the parietal peritoneum well localised?
As it receives the same nerve supply as the region of the abdominal wall that it lines.
What is parietal peritoneum sensitive to?
Pressure
Pain
Lacertion
Temperature
What does the visceral peritoneum cover?
The abdominal viscera
Where is the visceral peritoneum derived from?
Splanchnic mesoderm
What is the nerve supply to the visercal peritoneum?
The same as the viscera is covers
What is the visceral peritoneum sensitive to?
Stretch
Chemical irritation
Where is pain from the visceral peritoneum referred to?
Areas of the skin that are supplied by the same sensory ganglia and spinal cord segments as the viscera.
What is the peritoneal cavity?
A potential space between the parietal and visceral peritoneum.
What are intraperitoneal organs?
Organs enveloped by visceral peritoneum which covers the organ Botha anteriorly and posteriorly.
Name 3 intraperitoneal organs.
Stomach
Liver
Spleen
What are retroperitoneal organs?
Organs that are not associated with the visceral peritoneum - only covered with parietal peritoneum.
What are the 2 groups of retroperitoneal organs?
Primarily
Secondarily
What are primarily retroperitoneal organs?
Organs that develop and remain outside of the parietal peritoneum.
Name 3 primarily retroperitoneal organs.
Oesophagus
Rectum
Kidneys
What are secondarily retroperitoneal organs?
Organs which were initially intraperitoneal but became retroperitoneal as their mesentery fused with the posterior abdominal wall.
Name a secondarily retroperitoneal organ.
Ascending and descending colon.
Name the retroperitoneal organs.
Suprarenal (adrenal) glands
Aorta/ IVC
Duodenum (except proximal 2cm)
Pancreas (except tail)
Ureters
Colon (ascending and descending)
Kidneys
Oesophagus
Rectum
**SADPUCKER
What is a mesentery?
A double layer of visceral peritoneum that connects and intraperitoneal organ to the posterior abdominal wall.
What is omentum?
Consists of omenta sheets which extend from the stomach and proximal duodenum to connect them to other abdominal organs.
How many layers of visceral peritoneum does the greater momentum consist of?
4
Where does the greater omentum span between?
Greater curvature of the stomach > proximal part of the duodenum > anterior surface of transverse colon.
What is the role of the greater omentum in immunity?
It can migrate to infected viscera or to a site of surgical disturbance and wrap itself around the inflammation to ‘wall it off’ and protect other viscera.
What volume of lubricating fluid is secreted into the peritoneal cavity per day?
50ml
What can the peritoneal cavity be divided into?
Greater and lesser peritoneal sacs.
What is the greater peritoneal sac subdivided by?
Mesentery of the transverse colon.
What is the greater peritoneal sac divided into?
The supracolic and infra colic compartments.
Where does the supra colic compartment lie?
Above the transverse mesocolon.
Where does the infracolic compartment lie?
Below the transverse mesocolon.
What divides the infra colic compartment?
The mesentery of the small intestine.
What is the infra colic compartment divided into?
Right and left infra colic spaces.
What 3 things are contained within the supracolic compartment?
Stomach
Liver
Spleen
What 3 things are contained within the infra colic compartment?
Small intestine
Ascending colon
Descending colon
Where is the supracolic compartment positioned?
Largely under the costal ligaments of the thoracic cage.
What do the mesenteries do?
Enclose the intestines and attach them to the posterior abdominal wall.
What are the 4 mesenteries?
Small intestine
Transverse mesocolon
Sigmoid mesocolon
Mesoappendix
What is the small intestinal mesentery attached to?
Jejunum and ileum, connecting them to posterior abdominal wall
Where is the root of the small internal mesentery attached to?
the duodenal jejunal junction (to the left of L2 vertebra).
Where does the small intestinal mesentery attach to inferiorly?
Ileocaecal junction, close to right SI joint
What stimulates the encapsulated mechanoreceptors of the small intestine mesentery?
Traction and tension on the peritoneal folds in the upper abdomen
What are found in the region of the root of the small intestine mesentery?
Pacinian corpuscles (encapsulated mechanoreceptors)
What is the response of stimulated encapsulated mechanoreceptors?
Produce a drop in BP = reflex contraction of the abdominal wall
What does the sigmoid mesocolon do?
Attaches sigmoid colin to the pelvic wall.
Where is the top of the sigmoid mesocolon attached to?
Near the bifurcation of the left common iliac artery.
Where does the left limb of the sigmoid mesocolon descend to?
Descends medially to the medial border of the left psoas major muscle.
Where does the right limb of the sigmoid mesocolon descend to?
Into the pelvis and attaches anteriorly to the S3 vertebra
What does the greater omentum prevent?
The visceral peritoneum from adhering to the parietal peritoneum
What white cells can the omentum supply to fight infection?
Leucocytes
