Overview
This lecture covers the major cavities of the human body, their subdivisions, and the organs they contain, as well as the protection of vital organs like the brain and spinal cord.
Body Cavities: Definition and Importance
- Body cavities are fluid-filled spaces inside the body that hold and protect internal organs.
- Body cavities are separated by membranes and other structures to keep organs organized and protected.
- The two largest body cavities in humans are the ventral cavity (front) and dorsal cavity (back).
Ventral Cavity
- The ventral cavity is located at the anterior (front) of the trunk.
- It contains organs such as the lungs, heart, stomach, intestines, and reproductive organs.
- The ventral cavity allows organs to change shape and size without disrupting other tissues.
- It is subdivided into the thoracic cavity (chest) and abdominopelvic cavity (lower trunk).
- The thoracic cavity contains two pleural cavities (lungs) and the pericardial cavity (heart).
- The abdominopelvic cavity is further divided into the abdominal cavity (digestive organs, kidneys) and pelvic cavity (reproductive and excretory organs).
Dorsal Cavity
- The dorsal cavity is at the posterior (back) of the body, including the head and back of the trunk.
- It is subdivided into the cranial cavity (upper skull, contains brain) and spinal cavity (within vertebral column, contains spinal cord).
- The brain and spinal cord are protected by bones, meninges (three-layer membrane), and cerebrospinal fluid.
Protection of the Brain and Spinal Cord
- The meninges enclose and protect the brain and spinal cord and contain cerebrospinal fluid.
- Cerebrospinal fluid provides cushion and additional protection for the central nervous system.
Meningitis: Relevance to Body Cavities
- Meningitis is inflammation of the meninges from infection, which can cause severe complications if untreated.
- Symptoms include fever, headache, neck stiffness, confusion, and sensitivity to light/sound.
- It is diagnosed via lumbar puncture (spinal tap), which samples cerebrospinal fluid from the spinal cavity.
Key Terms & Definitions
- Body cavity — Fluid-filled space inside the body that holds and protects internal organs.
- Ventral cavity — Anterior trunk cavity containing lungs, heart, stomach, intestines, and reproductive organs.
- Thoracic cavity — Body cavity in the chest that holds the lungs and heart.
- Abdominopelvic cavity — Lower trunk cavity holding kidneys, digestive, and reproductive organs.
- Dorsal cavity — Posterior cavity including head and back, holding the brain and spinal cord.
- Cranial cavity — Cavity in the upper skull containing the brain.
- Spinal cavity — Long, narrow cavity in the vertebral column containing the spinal cord.
- Meninges — Three-layered membrane that encloses and protects the brain and spinal cord.
- Cerebrospinal fluid — Clear fluid produced by the brain, providing cushioning and protection in the meninges.
Action Items / Next Steps
- Review the subdivisions and contents of each major body cavity.
- Learn signs and symptoms of meningitis and their clinical relevance.
- Complete any assigned textbook questions on body cavities.