PERITONEUM AND MESENTERIES
I. PERITONEAL CAVITY
A. Bounded by a large continuous sheet of serous membrane (peritoneum) covering the contents of the abdominopelvic cavity and lining the wall of the abdominopelvic cavity
1. Parietal peritoneum - covers apparent walls of the cavity
2. Visceral peritoneum - covers viscera
B. Peritoneal reflections have several names
1. Mesenteries (mesentery) - double layer of peritoneum
2. Omenta (omentum) - extension of visceral peritoneum
3. Folds - reflections of peritoneum from underlying structures
4. Ligaments - mesentery between organs
5. Recess - pouch of peritoneum - clinically important
C. Greater peritoneal sac - most of peritoneal cavity
D. Lesser peritoneal sac (lesser omental bursa) - a subdivision of the original peritoneal sac that is "walled off" from the greater sac by various peritoneal folds and ligaments. It communicates with the greater sac at the epiploic foramen Winslow)
E. Retroperitoneal - term used to describe organs that are held against the body wall and appear to be covered by peritoneum - primary and secondary divisions
F. Intraperitoneal - term used to describe organs that are suspended from the body wall by a double fold of peritoneum called a mesentery
G. Nerve supply to the peritoneum
1. Parietal peritoneum
a. supplied by somatic nn. -sensitive to pain, temperature etc.
b. anterior and lateral abdominal wall - by nerves supplying overlying tissues
c. peripheral diaphragmatic area - by lower thoracic nn.
d. central diaphragmatic area - by phrenic nn.
2. Visceral peritoneum
a. devoid of most sensory innervation
b. some mesenteries are sensitive to stretch
H. Blood supply of the peritoneum - from vessels to adjacent body wall tissues and viscera
I. Functions of peritoneum
1. Secretes peritoneal fluid for lubrication of viscera - ascites fluid accumulation
2. Continuous movement of fluid toward subphrenic area for absorption by lymphatics
3. Adheres to similar surfaces when infected - tends to keep infections localized
4. Suspends organs, serves as location of vessels, lymphatics, nerves
5. Stores fat
II. PERITONEUM AND MESENTERIES IN THE ADULT
A. Related to the stomach
1. Lesser omentum - between stomach and proximal duodenum inferiorly and the visceral surface of the liver superiorly. Two subdivisions:
a. hepatogastric ligament
b. hepatoduodenal ligament
2. Greater omentum - hangs down from the stomach. Two subdivisions:
a. gastrocolic ligament
b. omental apron – “The Policeman of the Abdomen”
3. Gastrolienal ligament - from left side of stomach to spleen
4. Lienalrenal ligament - from spleen to left kidney
5. Lienophrenic ligament - upper spleen to diaphragm
6. Gastrophrenic ligament - upper left side of stomach to diaphragm
7. Lesser omental bursa - closed off portion of the peritoneal cavity between the lesser omentum, stomach and liver anteriorly and the posterior wall of the general peritoneum posteriorly
8. Epiploic foramen (of Winslow) - open connection between the lesser omental bursa and the greater peritoneal cavity. Bounded by:
a. hepatic triad (portal vein, hepatic artery, common bile duct) and associated peritoneum - anterior
b. inferior vena cava and associated peritoneum - posterior
c. duodenum (first part) - anterior/inferior
d. caudate lobe of liver - superior
B. Related to the liver
1. Falciform ligament - between anterior abdominal wall and liver
a. Ligamentum teres (Round ligament) - cord-like ligament in free edge of falciform ligament - remnant of the embryonic umbilical vein
2. Coronary ligament - connecting surface of liver to diaphragm
a. Triangular ligaments (right and left) "corners" of coronary ligament
b. Bare area of the liver - that portion of the liver not covered by peritoneum- within boundaries of coronary ligament
C. Related to the intestines
1. Mesentery - suspends the intestine from the body wall - usually refers to mesentery of jejunum and ileum
2. Mesocolon - mesentery of transverse colon
a. phrenicocolic ligament (sustentaculum lienis) - left-most extent of the mesocolon, directly inferior to the spleen
D. Blind inferior extent of peritoneal cavity has several names
1. Rectovesical pouch - <in the male> between the bladder and the rectum
2. Rectouterine pouch (of Douglas) – {in the female} between the rectum and the uterus
3. Vesicouterine pouch – {in the female} between the uterus and the bladder
E. Various peritoneal fossae, recesses, and spaces, which have not been discussed previously
1. Many fossae are discussed with specific organs. Examples are:
a. duodenal fossae
b. cecal fossa
c. intrasigmoid fossae
2. Subphrenic spaces
a. right and left anterior spaces - between diaphragm and liver
b. right posterior space - between liver, kidney and right colic flexure. Also called the hepatorenal pouch (of Morrison)
3. Paracolic gutters - along medial and lateral sides of ascending and descending colon
a. right medial gutter - closed off from pelvis by mesentery - closed off from subhepatic space by mesocolon
b. left lateral gutter - closed off from subhepatic space
c. other gutters - drain to pelvis or subhepatic space
d. hepatorenal space and pelvis tend to accumulate excess fluid in the reclining patient
4. Supracolic compartment of abdomen - area of cavity above transverse mesocolon
5. Infracolic compartment - area below transverse mesocolon