PERITONEUM AND MESENTERIES

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SB

Aorta

IVC

TrCol

PsUb

MESENTERY OVERVIEW

PERITONEUM

• Functions:

1. Minimize friction

2. Resist infection

3. Store fat

4. Pathway for neurovascular structures

PERITONEAL FLUID

• Derived from interstitial fluid of adjacent tissues

• Contains water, electrolytes, proteins, macrophages and lymphocytes

• Peritoneum is a semi-permeable membrane that allows fluid and cells to move in both directions

• Composition varies according to pathological condition

• Condition when there is excess fluid, usually due to inflammation or infection is called ascites

PERITONEAL STRUCTURES

• Parietal and visceral layers – single layer of peritoneum

• Mesentery – double layer that suspends gut tube, ie., dorsal mesentery and ventral mesentery

• Omentum – special type of mesentery that attaches stomach to another structure, ie., greater omentum and lesser omentum

• Peritoneal ligaments – double layer that attaches more solid viscera to abdominal wall or other organs

• Peritoneal folds – raised, single layer of peritoneum coursing over blood vessels and ligaments

MESENTERY

Dorsal Root of the Mesentery

Mesentery

VISCERAL PERITONEUM

• Intraperitoneal

– Organs nearly completely surrounded by peritoneum

– Organs suspended by mesentery, omentum or ligament

• Retroperitoneal

– Organs only partially covered by peritoneum

– Organs have no mesentery

MESENTERY OVERVIEW

DORSAL MESOGASTRIUM

• Rotation of stomach causes dorsal mesogastrium to balloon out to left

• Creates the lesser sac or omental bursa

28 days

48 days

DORSAL MESOGASTRIUM

• Splenorenal (lienorenal) ligament

• Gastrosplenic (gastrolienal) ligament

DORSAL MESOGASTRIUM – GREATER OMENTUM

DORSAL MESOGASTRIUM – GREATER OMENTUM

DERIVATIVES OF DORSAL MESOGASTRIUM

• Greater omentum (gastrocolic ligament)

• Gastrosplenic ligament

• Splenorenal ligament

VENTRAL MESENTERY

VENTRAL MESENTERY

• Rotation of stomach moves liver and lesser omentum to right

• Falciform ligament remains in midline

GREATER AND LESSER SACES

VENTRAL MESENTERY – LESSER OMENTUM

• Falciform ligament

Ligamentum teres

• Lesser omentum

Hepatogastric lig.

Hepatoduodenal lig.

DERIVATIVES OF VENTRAL MESENTERY

• Falciform, coronary & triangular ligaments

• Visceral peritoneum of liver

• Lesser omentum

– Hepatogastric ligament

– Hepatoduodenal ligament

MESENTERY PROPER AND MESOCOLON

PERITONEAL FOLDS

• Median umbilical fold – median umbilical ligament

• Medial umbilical folds – median umbilical ligaments

• Lateral umbilical folds – inferior epigastrics

PARACOLIC GUTTERS

• Longitudinal channels running along medial and lateral sides of ascending and descending colon

• Form where parietal peritoneum reflects onto colon as visceral peritoneum

PARACOLIC GUTTERS

HEPATORENAL RECESSRIGHT SUBHEPATIC RECESS

(MORRISON’S POUCH)

• One of the lowest points in the peritoneal cavity

• Excess fluid/blood will pool in this area when patient is supine

Summary• Dorsal Mesentery

• Dorsal mesogastrium

• Greater omentum

• Gastrosplenic ligament

• Lienorenal (splenorenal) ligament

• Dorsal Mesoduodenum

• Mesocolons (transverse and sigmoid)

• Ventral Mesentery

• Falciform ligament

• Coronary and triangular ligaments

• Lesser omentum - hepatogastric and hepatoduodenal ligaments