Abdominal Cavity Anatomy: Organs, Quadrants, and Clinical Relevance

Abdominal Cavity Overview

The abdominal cavity is the largest body cavity, housing most digestive organs plus the liver, spleen, kidneys, and adrenal glands. It is bounded superiorly by the diaphragm, inferiorly by the pelvic inlet, and lined by the peritoneum.

Four-Quadrant Division (Clinical Standard)

Two imaginary lines intersecting at the umbilicus divide the abdomen into quadrants for descriptive and diagnostic purposes:

Quadrant	Key Contents	Clinical Notes
Right Upper (RUQ)	Liver, gallbladder, hepatic flexure of colon, duodenum, head of pancreas, right kidney/adrenal	Cholecystitis, hepatitis, liver mets
Left Upper (LUQ)	Spleen, stomach, splenic flexure of colon, body/tail of pancreas, left kidney/adrenal	Splenic rupture, gastritis, pancreatitis
Right Lower (RLQ)	Cecum, appendix, terminal ileum, right ovary/fallopian tube, right ureter	Appendicitis, Crohn's, ovarian torsion
Left Lower (LLQ)	Sigmoid colon, descending colon, left ovary/fallopian tube, left ureter	Diverticulitis, colitis, ovarian cyst

Major Organs: Functions

• Liver: Largest solid organ; detoxification, bile synthesis, glycogen storage, protein synthesis, metabolism.
• Spleen: Immune filtration, RBC removal, platelet storage.
• Kidneys: Filtration, electrolyte/acid-base balance, blood pressure regulation (renin), erythropoietin production.
• Adrenal Glands: Cortisol, aldosterone, androgens, catecholamines—stress response, metabolism, BP.

Clinical Relevance

Quadrant localization guides physical exam, imaging interpretation, and differential diagnosis. For example, RUQ pain suggests biliary/hepatic pathology; RLQ pain raises concern for appendicitis. Cross-referencing with nine-region (organ-based) model enhances precision.