Peritoneum Flashcards
What are the subdivisions of peritoneum?
- Parietal layer
2. Visceral layer (serosa)
What is peritoneum?
A serous membrane lining the cavity abdomen and covering the abdominal organs
Describe the parietal layer of the peritoneum
Lines the body wall and has abundant pain fibers via nerves from the body wall
Describe the visceral layer (serosa) of the peritoneum
Covers viscera and lacks pain fibers
What is between parietal and visceral layers of the peritoneum?
peritoneal cavity
Define mesentery
Double layers of visceral peritoneum. So they lack pain fibers
They are called reflections: part of peritoneal lining that is not right against the body wall or the organ. It is between organs. Most of the time it is suspending an organ from the body wall.
Why are mesenteries important?
They keep things in place, maintain relationships among structures in the abdominal cavity. Transmit major vessels and nerves.
What are intraperitoneal organs?
organs covered on most sides by visceral peritoneum
Suspended by mesentery from the body wall
What are retroperitoneal organs?
Organs that lie deep to the parietal peritoneum and are covered by parietal peritoneum on one side only (so they do not have any mesentery)
What are examples of intraperitoneal organs-have a mesentery and are completely covered by the peritoneum?
In the abdominal peritoneal cavity: Stomach Small intestine Spleen Liver Gallbladder Cecum Large intestine
Pelvic peritoneal cavity:
Uterus
Ovaries
Uterine tubes
What are the retroperitoneal organs?
Primarily:
Kidneys, suprarenal glands, uterine cervix, ureters, gonads, aorta and inferior vena cava
Secondarily:
Duodenum (descending, horizontal, and ascending)
Ascending and descending colon
Pancreas and rectum (upper 2/3)
What is the nerve supply to the peritoneum?
Nerves from the adjacent body wall supply parietal peritoneum. The nerves supply pain and vasomotor fibers
What is the difference between primarily retroperitoneal and secondarily retroperitoneal?
Secondarily retroperitoneal became retroperitoneal during development
What are the three main types of peritoneal reflections in adults?
Mesenteries
Ligaments and folds
Omentum
What are peritoneal reflections?
Parts of peritoneal linings that are not against body wall or an organ, but sort of “hangs out” between structures in the abdomen
What are mesenteries?
2-layered fold of peritoneum
What is THE mesentery?
Attaches the “free” small intestine (jejunum and ileum) to the posterior body wall
Define transverse mesocolon
Mesentery of the transverse colon
Holds the transverse colon to the posterior body wall
Fuses with the posterior layer of the greater omentum
Define sigmoid mesocolon
Mesentery of the sigmoid colon
Holds the sigmoid colon to the posterior body wall
What is mesoappendix?
Mesentery of the vermiform appendix
The mesenteries of the duodenum, ascending colon, descending colon and cecum are usually lost during development. Since they are no longer suspended by a mesentery these organs are ________ ________.
Secondarily retroperitoneal
Define peritoneal ligaments
May be subdivisions of a larger structure
Usually transmit nerves and vessels
Usually lack connective tissue and are not the same as ligaments that join bones
What are some examples of peritoneal ligaments?
Gastrosplenic and splenorenal (lienorenal) ligament
Define omentum
(epiploon)
Broad, 2-4 layered sheet of peritoneum that attaches the stomach to other viscera
Define lesser omentum
Develops from the ventral mesogastrium (mesentery)
Runs from lesser curvature of the stomach to the liver
Subdivided into parts: Hepatogastric ligament (stomach to liver) Hepatoduodenal ligament (liver to duodenum)
Define greater omentum
Develops from the dorsal mesogastrium
4 layers
3 ligaments
What are the three ligaments of the greater omentum?
Gastrocolic ligament (stomach to transverse colon) Gastrophrenic ligament (stomach to diaphragm)(continuous with phrenicosplenic ligament) Gastrosplenic ligament (stomach to spleen)
What peritoneal ligaments are associated with the liver?
Coronary ligaments
Right and left triangular ligaments
Falciform ligament
Ligamentum teres hepatis
What is a fold?
A ridge or elevation in the peritoneum produced by underlying vessels
What are fossae (fossa) or recesses?
Depressions between folds
What are examples of folds and fossa?
Superior duodenal fold and fossa (recess)
Paraduodenal fossa
Inferior duodenal fold and fossa
Retroduodenal fossa
Fold formed by inferior mesenteric vein posterior to peritoneum
Structures coursing through the extraperitoneal tissue form elevations on the interior abdominal wall called what?
Peritoneal umbilical folds
What are the umbilical folds?
Median umbilical fold: inferiorly it forms the urachus (anchors the bladder). The fold is midline from bladder
Medial umbilical folds (2)
- medial umbilical ligaments
- obliterated umbilical as
Lateral umbilical folds (2)
- inferior epigastric vessels
- functional aa and vv
What are supraumbilical structures located on the internal aspect of the anterior abdominal wall?
Falciform ligament: curved remnant of the ventral mesogastrium
Ligamentum teres hepatis: Round ligament of the liver in its lower free border; obliterated umbilical vein
Define supravesical fossa
Fossa between the median and medial umbilical folds
Site for supravesical hernias (rare)
Define medial inguinal fossa
Fossa between the medial and lateral umbilical folds
Site for direct inguinal hernias
Also called inguinal triangle
Define Lateral inguinal fossa
Fossa lateral to the lateral umbilical folds
Site for indirect inguinal hernias
What makes up most of the “potential” space within the abdomen?
The greater sac
What are the subdivisions of the greater sac?
The greater sac and be subdivided into supracolic and infracolic regions by the colon and the transverse mesocolon
Define supramesocolic (supracolic) region
Superior and anterior to the liver and stomach
Includes hepatorenal and subphrenic spaces and fossae of the anterior wall
What are the recesses and fossae of the peritoneal cavity?
Subphrenic recess
Subhepatic/hepatorenal recess
Rectovesical/rectouterine recess
The peritoneal cavity is a (open/closed) potential space between parietal and visceral layers of peritoneum
Closed
Define inframesocolic region
Inferior and posterior part of the greater sac
Subdivided by mesenteries and “ligaments”
Clinically important spaces where intraperitoneal infections spread; phrenicocolic ligament limits the spread of fluid superiorly
What are lateral to the ascending and descending colon?
The infracolic compartments right and left paracolic gutters
What are the upper and lower parts of the inframesocolic region divided by?
THE mesentery into right and left infracolic spaces
The lesser sac (omental bursa) develops as part of the _______
Greater sac
How do greater and lesser peritoneal sacs communicate?
Through the epiploic foramen (of winslow)
Where is the lesser sac?
Posterior and inferior to the stomach
What are the recesses of the lesser sac
Superior recess: posterior to the liver
Inferior recess: Potential space between the 2 layers of the gastrocolic ligament
Splenic recess: Posterior to and left of the stomach
How is the lesser sac clinically important?
Important relationship to the liver, pancreas, stomach and spleen
