Peritoneum Flashcards
Features of peritoneum
-Continuous, glistening and slippery transparent serous membrane
Consists of 2 layers:
-parietal peritonuem lines internal surface of the abdominopelvic cavity
-visceral peritoneum lines internal viscera such as stomach and intestines
-Both layers consist of mesothelium - layer of simple squamous epithelia cells
What is the peritoneal cavity?
-Potential space between 2 layers of peritoneum
-Contains thin film of peritoneal fluid
-This lubricates peritoneal surfaces enabling viscera to move over each other without friction (aids digestion)
Peritoneal cavity in males and females
-Completely closed in males
-In females, communication pathway to external environment through uterine tubes, uterine cavity and vagina
-Provides potential pathway of infection from external environment to peritoneal cavity
Embryology of the peritoneum
-Embryonic gut tube is connected to body wall by ventral and dorsal mesenteries
-Ventral mesentery largely disappears except for parts connected to liver (falciform ligament)
-Dorsal mesentery suspends gut tube from posterior abdominal wall
-Arteries supplying gut tube pass between the dorsal mesentery
What is a mesentery?
-Double layer of peritoneum that occurs as a result of the invagination of the peritoneum by an organ.
-It is where the visceral layer becomes continuous with the parietal layer
-Small intestine mesentery is called “the mesentery”
What is the omentum?
-Double layered extension or fold of peritoneum that passes from stomach and proximal part of duodenum to adjacent abdominal organs
Greater omentum definition
-4 layered peritoneal fold that hangs down like an apron from the greater curvature of the stomach and the proximal part of the duodenum
-After descending, it folds back and attaches to the anterior surface of the transverse colon
Lesser omentum definition
-Double layered peritoneal fold that connects the lesser curvature of the stomach and the proximal part of the duodenum to the liver
What is a peritoneal ligament?
-Double layered peritoneum that connects an organ with another organ or to the abdominal wall
Liver connections
The liver is connected to the:
-anterior abdominal wall by the falciform ligament
-stomach by the hepatogastric ligament (part of lesser omentum)
-duodenum by the hepatoduodenal ligament (part of the lesser omentum)
What connects the stomach to the spleen?
-Gastrosplenic ligament
What are bare areas?
-Every organ has an area not covered with visceral peritoneum to allow the entrance or exit of neurovascular structures
-These are called bare areas
What is a peritoneal fold?
-Reflection of peritoneum that is raised from body wall by underlying blood vessels, ducts and ligaments formed by obliterated fetal vessels (e.g. umbilical folds on internal surface of the anterolateral abdominal wall)
List the umbilical folds
-1 median umbilical fold extends from apex of urinary bladder to the umbilicus and extends and covers the median umbilical ligament - a fibrous remnant of the urachus that joined the apex of the fetal bladder to the umbilicus
-2 medial umbilical folds cover the medial umbilical ligaments, formed by the occluded parts of the umbilical arteries
-2 lateral umbilical folds cover the inferior epigastric vessels and therefore bleed if cut
Development of the stomach
-Different growth rates in various regions in the wall
90 degrees clockwise rotation
-Left side faces anteriorly
-Right side faces posteriorly
Rotation on the anteroposterior axis
-Cephalic end moves to the left and downward
-Caudal end moves to the right and upward
Development of the liver
-Liver grows at a faster rate on the right compared to the left
-Expansion of the liver forces other organs to the left
-Rotation of the stomach also facilitates these movements of the organs
Greater and lesser sac
-As liver adopts its final position on the right, the right side of the peritoneal cavity is pushed posterior to the stomach and lesser omentum
-Space behind stomach is lesser sac or omental bursa
-Rest of space is greater sac
Omental bursa (lesser sac)
-The omental bursa extends superiorly and inferiorly
-Superior recess limited by the diaphragm
-Inferior recess between the layers of the greater omentum
How do the greater and lesser sacs communicate?
-The epiploic (omental) foramen
-Located posterior to the free edge of the lesser omentum (hepatoduodenal ligament)
Boundaries:
-Anteriorly - the hepatoduodenal ligament
-Posteriorly - the IVC
-Superiorly - the liver
-Inferiorly - first part of the duodenum
Supracolic and infracolic compartments
-Transverse mesocolon divides greater sac into supracolic compartment and infracolic compartment
-Infracolic compartment lies posterior to greater omentum and is divided into right and left colic spaces by the mesentery
-Free communication occurs between supracolic and infracolic compartments through the paracolic gutters
What are the paracolic gutters?
-Grooves between the lateral aspect of the ascending/descending colon and the posterolateral abdominal wall
Summary of the peritoneal cavity
-Peritoneal cavity is a closed cavity, lined by the peritoneum and surrounded on all sides by the extraperitoneal cavity
-Laterally, anteriorly and superiorly, the extraperitoneal cavity appears like a very narrow split
-Only the retroperitoneal space (posterior) and extraperitoneal space (inferior) are true spaces that contain organs
Intraperitoneal vs Retroperitoneal organs
Intraperitoneal - Organs that are completely invested by visceral peritoneum
Retroperitoneal - Organs that lie against the posterior body wall and are covered by peritoneum on their anterior surface only
Primary and Secondary retroperitoneal organs
Primary - Retroperitoneal when they were formed
Secondary - They migrated posterior to the peritoneum during embryonic development
Examples of primary and secondary retroperitoneal organs
Primary:
-Kidneys
-Suprarenal glands
Secondary:
-Ascending colon
-Descending colon
-Pancreas
