Anatomy and Physiology Lecture: Body Cavities and Membranes

Overview

• Major body cavities and membranes protect and compartmentalize organs, similar to a toolbox.
• Two major cavities: Ventral cavity (larger) and Dorsal cavity (smaller).

Body Cavities

Dorsal Cavity

• Located towards the back of the body.
• Houses the central nervous system.
• Subdivided into:
  • Cranial Cavity: Contains the brain.
  • Vertebral Cavity: Contains the spinal cord.
• Membranes: Lined by the meninges (dura mater, arachnoid, pia mater).

Ventral Cavity

• Located towards the front of the body.
• Contains visceral organs (guts).
• Subdivided into:
  • Thoracic Cavity (situated above the diaphragm):
    • Contains heart, lungs, trachea, and esophagus.
    • Subdivided into:
      • Left Pleural Cavity: Houses left lung.
      • Right Pleural Cavity: Houses right lung.
      • Mediastinum: Midway section housing heart (in pericardial cavity), esophagus, thymus gland, and trachea.
  • Abdominopelvic Cavity (below the diaphragm):
    • Abdominal Cavity: Contains liver, stomach, pancreas, spleen, gallbladder, intestines, kidneys.
    • Pelvic Cavity: Contains bladder, reproductive organs, distal portions of large intestine.

Body Membranes

Dorsal Body Cavity

• Protected by the meninges.
  • Meningitis: Inflammation of the meninges, can cause severe neck stiffness.

Ventral Body Cavity

• Contains serous membranes filled with serous fluid for lubrication and movement:
  • Pleura: Lines pleural cavity and covers each lung.
  • Pericardium: Lines pericardial cavity and covers the heart.
  • Peritoneum: Lines peritoneal cavity in abdominopelvic region.

Membrane Layers

• Visceral Layer: Touches the organ (viscera).
• Parietal Layer: Lines the cavity wall.
• Directional Terms:
  • Visceral Pleura: Touches the lung.
  • Parietal Pleura: Lines thoracic cavity wall.

Additional Terms

• Retroperitoneal: Organ behind peritoneal space.
• Intraperitoneal: Organ within peritoneal space.
• Subperitoneal: Organ below peritoneal space.

Recap

• Major Cavities:
  • Dorsal Cavity: Cranial and vertebral; lined by meninges.
  • Ventral Cavity: Thoracic (pleura around lungs, pericardium around heart), abdominopelvic (peritoneum).
• Cavity Separators:
  • Diaphragm separates thoracic and abdominopelvic cavities.

Additional Resources

• Free quiz and additional videos on anatomy and physiology available through provided links.