Chapter 12: Central Nervous System

Overview

• Focus on the brain and spinal cord.
• Emphasis on the four regions of the adult brain and their functions.
• PowerPoint slides are essential for understanding; textbook contains too much information.

Worksheets

• Concentrate on the functions of the four brain regions.
• Use worksheets to gather information but also review slides.

Embryology of the CNS

• Brain and spinal cord originate from a neural tube.
• Neural Tube Structure:
  • Anterior End: Develops into three primary vesicles.
  • Posterior End: Forms the spinal cord.

Primary Brain Vesicles

1. Proencephalon (Forebrain)
2. Mesencephalon (Midbrain)
3. Rhombencephalon (Hindbrain)

Development of Vesicles

• Proencephalon ➔ Telencephalon and Diencephalon
• Mesencephalon remains unchanged as a secondary vesicle.
• Rhombencephalon ➔ Metencephalon and Myelencephalon

Adult Brain Structures

• Telencephalon becomes the cerebrum.
• Diencephalon includes the thalamus, hypothalamus, and epithalamus.
• Mesencephalon forms part of the brainstem (midbrain).
• Metencephalon ➔ Pons
• Myelencephalon ➔ Medulla oblongata

Brain Tissue Composition

• Gray Matter: Non-myelinated neurons and cell bodies. Appears darker.
• White Matter: Mostly myelinated axons. Appears lighter due to fatty myelination.

Distribution in CNS

• Spinal Cord: Central gray matter (butterfly shape) surrounded by white matter.
• Brainstem: Central gray matter surrounded by white matter with scattered gray nuclei.
• Cerebral Hemispheres:
  • Exterior gray matter (cerebral cortex).
  • Central white matter with scattered gray nuclei (brain nuclei).