Peritoneum and Major Abdominal Vessels

Richard D. Lane, Ph.D.Professor and Acting ChairmanDepartment of Neurosciences

Room 103, Block HSBRlane@meduohio.edu

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• Peritoneum: A large, thin, transparent sheet of serous membrane which lines the walls of the abdominopelvic cavity and is reflected onto the viscera.

•– Parietal peritoneum: lines the abdominal and pelvic walls.

•– Visceral peritoneum: covers abdominal and pelvic organs.

– Peritoneal Cavity: potential space between adjacent layers of peritoneum usually containing a small amount of fluid.

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SmIntestine

Peritoneal Cavity

ParietalPeritoneum

VisceralPeritoneum

Mesentery

• Peritoneal Cavity:• Subdivided by the greater and lesser omentum into

two sacs called the Greater and Lesser sacs (omental bursa). The Omental foramen (Epiploic foramen) connects the 2 sacs.

• Closed space in males, communicates with exterior in females.

Mesentery: Double layer of peritoneum that connects an intraperitoneal organ to the posterior

abdominal wall.

Has a connective tissue core in which blood vessels, nerves and lymphatics travel to and from the intraperitoneal organ.

Organs with a mesentery are freely movable.

Intraperitoneal Organs: covered with visceral peritoneum except at sites where the mesentery attaches.

• Examples: 1) Small intestine

• 2) Spleen

Retroperitoneal (Extraperitoneal) Organs: not covered with visceral peritoneum on one or more sides.

Do not have a mesentery.

Some organs are secondarily retroperitoneal.

Omentum: Double layer of peritoneum attached to the stomach and proximal part of duodenum.

– Lesser Omentum: Attaches the stomach (along the lesser curvature) to the liver. Subdivided into 2 ligaments

(hepatogastric and hepatoduodenal ligaments).

– Greater Omentum: Attaches the stomach (along the greater curvature) to the posterior abdominal wall.

Subdivided into 3 ligaments (gastrophrenic, gastrosplenic, and gastrocolic ligaments).

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•Peritoneal Ligaments: Double layer of peritoneum which connect organs to organs or

organs to the body wall.

• Examples: 1) Gastrophrenic ligament • 2) Hepatoduodenal ligament

Gastrocolic ligament

Gastro-Splenicligament

Gastrophrenic ligament

Hepatogastric ligamentHepatoduodenal ligament Hepatic A. Portal V. Bile duct

Lesser Sac

Omental Foramen

Stomach

TC

Greater Sac(red area)

ANTERIOR

Subphrenic recessCoronary ligaments

Superior recess

Stomach

Spleen

GreaterSac

Lesser Sac

Hepatorenal Pouch

OmentalForamen

Hepatosplenic ligament

Splenorenalligament

LeftRight

Peritoneal folds: A ridge on the surface of the body wall covered with parietal peritoneum. The ridge is produced by an underlying vessel, duct or obliterated fetal vessel.

Lateral umbilical fold(inferior epigastric v.s)

Medial umbilical fold(obliterated umbilical artery)

Median umbilical fold)(urachus)

Peritoneal Recesses or Fossa: a pouch of peritoneum formed by peritoneal folds or ligaments.

Peritoneal Gutters

Transverse colon

SupracolicCompartment

InfracolicCompartmnent

HRP

Right paracolicgutter

Left paracolic gutter

Rectouterinepouch

RInfracolicspace

L Infracolicspace

Mesentery

RPG

LPG

Celiac artery

Superior mesenteric artery

Inferior mesentericartery

Abdominal aorta

Common iliac arteries

Common hepatic artery

Proper hepatic artery

Marginal artery of DrummondAnastamosing channels connecting The branches of the SMA and IMA

Left colicartery

Sigmoidalartery

Superior rectalartery

The hepatic portal venous system begins at the venous ends of capillaries in the organs of the GI tract and ends at the venous sinusoids in the liver.

The portal vein is formed by the joining of the splenic vein with the superior mesenteric vein. The inferior mesenteric vein usually joins the splenic vein.

• Portal hypertension: Occurs when portal circulation through the liver is obstructed by liver disease (cirrhosis) or tumor. The high portal pressure promotes the enlargement (varices) of alternate pathways to the caval system.