Lecture Notes: Central Nervous System and Brain Structure

Overview

• Central Nervous System (CNS): Consists of the brain and spinal cord.
  • Brain: Most complex known object with countless neuronal connections.
  • Consciousness production is not fully understood.
• Peripheral Nervous System (PNS): To be discussed separately.

Brain Structure and Development

• Embryonic Development: Brain and spinal cord start as a neural tube.
  • Primary Brain Vesicles:
    • Prosencephalon (Forebrain)
    • Mesencephalon (Midbrain)
    • Rhombencephalon (Hindbrain)
  • Secondary Brain Vesicles:
    • Forebrain: Telencephalon and Diencephalon
    • Midbrain: Remains unchanged
    • Hindbrain: Metencephalon and Myelencephalon

Adult Brain Regions

• Cerebral Hemispheres
  • Telencephalon develops into cerebral hemispheres (cerebrum).
• Brain Stem: Composed of the midbrain and hindbrain segments.
• Cerebellum
• Ventricles: Hollow cavities filled with cerebrospinal fluid.

Neuroglia in the CNS

• Astrocytes: Branches perform regulatory functions.
• Microglial Cells: Monitor neuron health.
• Oligodendrocytes: Form myelin sheaths.

Detailed Brain Structure

• Cerebral Hemispheres: Majority of brain mass.
  • Gyri: Ridges
  • Sulci: Grooves
  • Fissures: Deep grooves
  • Lobes: Frontal, Parietal, Temporal, Occipital, and Insula
  • Regions:
    • Cerebral Cortex: Gray matter, site of the conscious mind.
    • White Matter: Myelinated fibers.
    • Basal Nuclei: Gray matter within white matter.

Functional Areas of the Cortex

• Motor Areas
  • Primary Cortex: Controls voluntary motion.
  • Premotor Cortex: Plans movements.
  • Broca’s Area: Speech production.
  • Frontal Eye Field: Controls eye movement.
• Sensory Areas
  • Primary Somatosensory Cortex: Receives sensory info.
  • Visual, Auditory, Olfactory, Gustatory, Visceral, Vestibular Cortices: Process respective sensory info.
• Association Areas
  • Multimodal: Anterior, Posterior, and Limbic areas.

Diencephalon

• Thalamus: Directs information to the cortex.
• Hypothalamus: Regulates autonomic functions, body temperature, endocrine system.
• Epithalamus: Houses the pineal gland.

Brain Stem and Cerebellum

• Brain Stem: Midbrain, Pons, Medulla Oblongata.
• Cerebellum: Regulates muscle contraction for coordination.

Brain Protection

• Meninges: Connective tissue membranes.
  • Dura Mater: Outer layer.
  • Arachnoid Mater: Middle layer with blood vessels.
  • Pia Mater: Delicate inner layer.

Spinal Cord

• Location: Within the vertebral column, protected by cerebrospinal fluid and meninges.
• Spinal Nerves: 31 pairs.
• Gray Matter: Butterfly shape with neurons.
• White Matter: Nerve fibers for communication between brain and cord.

Conclusion

• Future Topics: More detailed exploration of pathways and the nervous system branches in upcoming lectures.