Abdominal Cavity 1pdf

Abdominal Cavity

  • Definition

    • Major part of the abdominopelvic cavity

    • Located between the diaphragm and pelvic inlet

    • Separated from the thoracic cavity by the thoracic diaphragm

    • Continuous inferiorly with the pelvic cavity

    • Extends superiorly up to the 4th intercostal space

Contents of the Abdominal Cavity

  1. Digestive System Organs

    • Stomach, liver, intestines, pancreas

  2. Urinary System Organs

    • Kidneys, ureters

  3. Lymphatic Organs

    • Spleen, lymph nodes

  4. Endocrine Glands

    • Suprarenal glands, ovaries

  5. Autonomic Nerve Plexuses

  6. Serous Membrane

    • Peritoneum

Divisions of Abdominal Cavity

  1. Peritoneal Cavity

  2. Retroperitoneal Space

Peritoneum

  • Continuous, glistening, slippery, transparent serous membrane

  • Lines the abdominopelvic cavity and invests the viscera

  • Largest serous membrane of the body

  • Composed of simple squamous epithelium (mesothelium) with thin subepithelial connective tissue

  • Has two continuous layers:

    1. Parietal Peritoneum

      • Lines inner surface of the abdominal wall

      • Vascular supply comes from corresponding wall

    2. Visceral Peritoneum

      • Covers peritoneal organs

      • Vascular supply comes from the vasculature of covered organs

      • Insensitive to touch, heat, cold, and lacerations

Divisions of Abdominal Organs with Respect to Peritoneum

  1. Intraperitoneal Organs

    • Develop in the peritoneum

    • Have complete visceral peritoneal covering

    • Fixed by double fold of peritoneum (mesentery)

    • Examples: liver, stomach, spleen, parts of the duodenum, jejunum, ileum, cecum, appendix, transverse colon, sigmoid colon

  2. Primary Retroperitoneal Organs

    • Develop outside the peritoneum

    • Lie on posterior abdominal wall, covered by peritoneum only anteriorly

    • Examples: kidneys, ureters, aorta, inferior vena cava (IVC), thoracic duct, sympathetic trunk

  3. Secondary Retroperitoneal Organs

    • Originally developed within peritoneum but later partially lost their peritoneal cover

    • Examples: parts of the duodenum (2nd, 3rd, 4th), pancreas, ascending colon, descending colon, part of the rectum

Peritoneal Cavity

  • Lies within abdominal cavity

  • Continuous inferiorly into the pelvic cavity

  • A potential space between two peritoneal layers

  • Contains thin film of lubricating fluid

  • Contains no organs

  • Peritoneal fluid allows viscera to move over each other, aiding digestion

  • Completely closed sac in males, but in females, uterine tubes open into it, allowing for patency and blockage checks

Functions of the Peritoneum

  1. Reduce Friction

  2. Defense Against Diseases

    • Rich in macrophages and lymphocytes

  3. Storage of Fat

  4. Absorption and Secretion

  5. Localize Infections

    • Via exudates

Clinical Notes

  • Ascites: Excessive accumulation of fluid in peritoneal cavity

  • Abdominal Paracentesis: Removal of fluid from peritoneal cavity

  • Peritoneal Dialysis: Removal of substances and water by transfer across the peritoneum

Innervation of the Peritoneum

  • Parietal Peritoneum: Sensitive to pain, innervated by:

    1. Sensory and vasomotor nerves of adjacent body wall

    2. Phrenic nerve supply to subdiaphragmatic part

    3. Thoracoabdominal and subcostal nerves

    4. Branches of lumbosacral plexus (iliohypogastric and ilioinguinal nerves)

  • Visceral Peritoneum

    • Insensitive to pain, innervated by autonomic visceral nerves

Folds of the Peritoneum

  • Separate viscera, bind organs together, and connect them to the abdominal wall

  • Contain blood vessels and nerves

  • Reflections between organs or between the body wall and organs termed ligaments

    • Examples: hepatogastric ligament, hepatoduodenal ligament, gastrocolic ligament, gastrosplenic ligament, gastrophrenic ligament, lienorenal ligament, falciform ligament, umbilical fold

Omentum

  • Double-layered reflection of peritoneum that connects the stomach to neighboring organs

  • Lesser Omentum:

    • Connects lesser curvature of the stomach and proximal part of the duodenum to the liver

    • Contains: right and left gastric vessels, gastric lymph nodes, hepatic artery, bile duct, portal vein

  • Greater Omentum:

    • Hangs like an apron from greater curvature of stomach and proximal duodenum

    • After descending, folds back to attach to anterior surface of transverse colon

    • Contains: right and left gastroepiploic vessels, fat, lymph nodes

Functions of Greater Omentum

  1. Storage of Fat

  2. Localization of Infection

  3. Prevention of Adherence

  4. Defense Against Infection

  5. Protection

Divisions of Peritoneal Cavity

  1. Greater Sac

    • Lies between inner surface of anterior abdominal wall and abdominal organs

    • Divided by greater omentum, transverse colon, and mesocolon into:

      • Supracolic Compartment: Contains stomach, liver, spleen

      • Infracolic Compartment: Contains small intestine, ascending and descending colons

    • Infracolic compartment further divided into right and left infracolic spaces by mesentery of small intestine

    • Supracolic and infracolic compartments communicate through paracolic gutters

  2. Lesser Sac (Omental Bursa)

    • Lies posterior to the stomach and lesser omentum

    • Communicates with the greater sac through epiploic foramen (foramen of Winslow)

    • Inferior vena cava lies behind epiploic foramen

Boundaries of the Epiploic Foramen

  • Anteriorly: hepatoduodenal ligament with portal triads

  • Posteriorly: IVC, right crus of diaphragm, right suprarenal gland

  • Superiorly: liver (caudate lobe) covered with peritoneum

  • Inferiorly: superior (first) part of duodenum

Boundaries of the Lesser Sac

  • Anteriorly:

    • Posterior wall of stomach, lesser omentum, greater omentum, first part of duodenum, vessels of the stomach

  • Right: liver, duodenum, and IVC

  • Left: spleen, gastrosplenic, and gastrophrenic ligaments

  • Posteriorly:

    • Diaphragm, pancreas, left kidney, left suprarenal gland, duodenum, abdominal aorta, gastropancreatic fold with left gastric vessels, pancreaticoduodenal fold with common hepatic and right gastric arteries

Parts of the Lesser Sac

  • Vestibule

  • Body

  • Recesses:

    • Superior Recess: Lies behind liver

    • Inferior Recess: Lies behind stomach and in greater omentum

    • Splenic Recess: Part of inferior recess extending to spleen

Clinical Significance of Lesser Sac

  • Infection: Explains how it spreads from nearby organs

  • Accumulation: Fluid, blood, pus

  • Hernias: Small recesses formed by peritoneal folds can trap intestine, causing internal or Treitz hernias

  • Surgical Approaches:

    1. Through lesser omentum

    2. Through gastrocolic ligament

    3. Through transverse mesocolon (common)

Abdominal Viscera

  • Principal organs include:

    • Terminal part of esophagus

    • Stomach

    • Intestines

    • Spleen

    • Pancreas

    • Liver

    • Gallbladder

    • Kidneys

    • Suprarenal glands

Esophagus

  • Muscular tube approximately 25 cm long and 2 cm in diameter

  • Functions: conveys food from pharynx to stomach

  • Has three normal constrictions:

    1. Cervical constriction

    2. Thoracic (broncho-aortic) constriction

    3. Diaphragmatic constriction (physiological inferior esophageal sphincter)

  • Crosses diaphragm at level T10

  • Terminates at cardiac orifice of stomach (level T11)

  • Length of abdominal esophagus: 1.25 cm

Arterial Supply of Abdominal Esophagus

  • Left gastric artery

  • Left inferior phrenic artery

Venous Drainage of Abdominal Esophagus

  • Left gastric vein (to portal venous system)

  • Esophageal veins (to azygos vein)

Lymphatic Drainage of Esophagus

  • Left gastric lymph nodes drain into celiac lymph nodes

Innervation of Abdominal Esophagus

  • Esophageal nerve plexus formed by vagal trunk and thoracic sympathetic trunks

Stomach

  • Most dilated part of the alimentary canal (25 cm long, 14 cm wide)

  • Capacity: 30ml at birth, 1000ml at puberty, 2000ml in adults

  • J-shaped structure between esophagus and small intestine

  • Functions: storage of food, chemical digestion, formation of chyme by churning

Parts of the Stomach

  1. Cardia: Surrounds cardiac orifice at T10-T11 level, fixed part of the stomach

  2. Fundus: Dilated superior part, related to left dome of diaphragm, may dilate by gas, fluid, or food

  3. Body: Major part between fundus and pylorus

  4. Pyloric Part: Funnel-shaped, controls discharge into duodenum, surrounded by pyloric sphincter

  • Normally lies in epigastric, umbilical, and left hypochondriac regions

Curvatures of the Stomach

  1. Lesser Curvature: Shorter, concave right border; attachment for lesser omentum

  2. Greater Curvature: Longer, convex left border; attachment for greater omentum, gastrosplenic, and gastrophrenic ligaments

Interior of the Stomach

  • Gastric mucosa forms folds known as rugae; pronounced in pyloric region

  • Height and number of rugae vary with distension

  • Gastric canal formed between longitudinal folds; saliva, foods, and fluids pass through these canals

  • Gastric pits or foveolae gastricae present on the mucosal surface

Relations of the Stomach

  • Anteriorly: Diaphragm, left lobe of liver, anterior abdominal wall

  • Posteriorly: Left crus of the diaphragm, left suprarenal gland, left kidney, pancreas, transverse mesocolon, splenic artery and vein, transverse colon

Arterial Supply of the Stomach

  • Supplied by celiac trunk and its branches

  • Major arteries include:

    1. Right gastric artery (lesser curvature)

    2. Left gastric artery (lesser curvature)

    3. Right gastroepiploic artery (greater curvature)

    4. Left gastroepiploic artery (greater curvature)

    5. Short gastric artery

Venous Drainage of the Stomach

  • Drain via veins accompanying arteries:

    1. Right gastric vein to portal vein

    2. Left gastric vein to portal vein

    3. Prepyloric vein to right gastric vein

    4. Left gastroepiploic vein to splenic vein

    5. Short gastric vein to splenic vein

    6. Right gastroepiploic vein to superior mesenteric vein

Lymphatic Drainage of the Stomach

  • Drained by various lymph nodes:

    • Left gastric, right gastric, left gastroepiploic, right gastroepiploic lymph nodes

    • Drains into celiac lymph nodes and ultimately to cisterna chyli and thoracic duct

Innervation of the Stomach

  • Parasympathetic supply from anterior and posterior vagal trunks

  • Sympathetic supply from T6-T9 segments through greater splanchnic nerve

  • Highly selective vagotomy to manage gastric secretions

Mucosal Barrier

  • Gastric juice concentrated 100,000 times more than blood

  • Stomach protects from self-digestion via:

    • Bicarbonate-rich mucus on the wall

    • Tight junctions between epithelial cells

    • Glandular cells impermeable to HCl

    • Surface epithelium renewed every 3 to 6 days

Greater and Lesser Sac

Greater Sac

  • Definition: The greater sac lies between the inner surface of the anterior abdominal wall and the abdominal organs.

  • Divisions: It is divided by the greater omentum and transverse colon into:

    • Supracolic Compartment: Contains stomach, liver, spleen.

    • Infracolic Compartment: Contains small intestine and ascending/descending colons.

  • Communication: The compartments communicate through paracolic gutters.

Lesser Sac (Omental Bursa)

  • Definition: The lesser sac lies posterior to the stomach and lesser omentum and communicates with the greater sac through the epiploic foramen.

  • Boundaries:

    • Anteriorly: Posterior wall of stomach, lesser omentum, greater omentum, first part of duodenum.

    • Right: Liver, duodenum, IVC.

    • Left: Spleen and associated ligaments.

    • Posteriorly: Diaphragm, pancreas, left kidney, left suprarenal gland.

  • Parts of the Lesser Sac:

    • Vestibule: The entry area of the lesser sac.

    • Body: Main part of the lesser sac.

    • Recesses:

      • Superior Recess: Lies behind liver.

      • Inferior Recess: Lies behind stomach in greater omentum.

      • Splenic Recess: Part of inferior recess extending to spleen.

Functions

  • Greater Sac: Acts as a space for organs and facilitates movement during digestion.

  • Lesser Sac: Provides a potential space for infections or fluid accumulation.

Figures illustrating these anatomical spaces would enhance understanding but are not included in this note.

W (Double U):

  • Definition: W is the 23rd letter in the English alphabet.

  • Phonetics: Pronounced as /ˈdʌbəl juː/.

  • History: Originated from the Latin letter V, initially represented as a double V.

  • Usage: Used in various contexts including mathematics (e.g. W as a symbol for work), physics (e.g. W for watt), and as a variable in equations.

  • Cultural Significance: Represents values like "win" in sporting contexts, often used as a colloquial expression.