Introduction to the Central Nervous System

• Central Nervous System (CNS): Composed of the brain and spinal cord.
  • Central anatomically (located in the middle of the body).
  • Central functionally (site of information integration).

Brain Structure

• Protection:

  • Encased in the skull.
  • Surrounded by three protective layers known as meninges:
    1. Pia Mater: Soft layer adherent to the brain.
    2. Arachnoid Mater: Spider web-like layer with projections.
    3. Dura Mater: Tough outer layer (like a paper bag).

• Cerebral Spinal Fluid: Located between the pia mater and arachnoid mater.

• Meningitis: Infection or inflammation of the meninges.

Parts of the Brain

1. Cerebrum:

   • Made up of multiple lobes.
   • Contains gray matter (cell bodies) and white matter (axons).
   • Functions:
     • Frontal Lobe: Contains the motor cortex (initiates movement).
     • Parietal Lobe: Contains the somatosensory cortex (processes sensation).
     • Occipital Lobe: Contains the visual cortex (processes visual information).
     • Temporal Lobe: Contains the auditory cortex (processes sound).

2. Cerebellum:

   • Also known as the "small brain".
   • Roles:
     • Maintains tone, posture, and balance.

3. Brain Stem:

   • Composed of three parts:
     1. Midbrain
     2. Pons
     3. Medulla Oblongata (Medulla)
   • Functions:
     • Houses most cranial nerves (important for head and neck functions).
     • Regulates respiratory and cardiovascular rhythms.
     • Responsible for reflexes (e.g., blink reflex, cough reflex, vomiting reflex).

Spinal Cord

• Regions:

  • Divided into cervical, thoracic, lumbar, sacral, and coccygeal regions.
  • Contains 31 pairs of peripheral nerves.

• Reflex Actions:

  • Reflexes occur at the spinal cord level, bypassing the brain (e.g., moving hand away from hot surface).

Conclusion

• Overview of the parts and functions of the central nervous system.