Neuroanatomy Lecture Notes

Key Concepts

• Central Nervous System (CNS)

  • Components: Brain and Spinal Cord
  • Functions:
    • Collects sensory information from the environment and the body
    • Compares current information with past experiences
    • Processes and integrates sensory information
    • Makes decisions and generates motor responses (movement or gland secretion)

• Peripheral Nervous System (PNS)

  • Divided into sensory and motor systems
  • Functions:
    • Sensory: Collects information from the body and sends it to the CNS
    • Motor: Carries motor responses from the CNS to the periphery
  • Further divided into:
    • Motor: Voluntary (somatic) and involuntary (autonomic)
      • Autonomic further divided into Sympathetic (stress-related) and Parasympathetic (rest-related)
    • Sensory: General (touch, temperature) and Special (vision, taste, smell)

Detailed Breakdown

CNS Functions

• Sensory Input: Collects and processes environmental information
• Processing: Compares current sensory input with past data
• Decision Making: Determines responses based on integrated information
• Motor Output: Sends motor commands to effectors (muscles/glands)

PNS Functions

• Sensory Division: Collects sensory input from the body
  • Special Senses: Vision, Hearing, Smell, Taste, Balance
  • General Senses: Touch, Temperature, Pain, Proprioception (sense of body position)
• Motor Division: Executes commands from the CNS
  • Somatic (Voluntary): Controls skeletal muscles
  • Autonomic (Involuntary): Controls smooth muscles, cardiac muscles, and glands
    • Sympathetic: Activates during stress (fight or flight response)
    • Parasympathetic: Activates during rest (rest and digest)

Structural Aspects

• Gray Matter: Collections of neuronal cell bodies within the CNS
  • Cortex: Gray matter on the surface
  • Nucleus: Gray matter embedded within the CNS surrounded by white matter
• White Matter: Collections of axons within the CNS
  • Tracts: Groupings of axons that run up and down the CNS
    • Ascending Tracts: Carry sensory information to the brain
    • Descending Tracts: Carry motor information from the brain
  • Commissural Fibers: Connect left and right sides of the CNS
  • Association Fibers: Connect different regions within the same hemisphere (anterior-posterior)
  • Reticular Formation: Network of mixed gray and white matter in the brainstem

Peripheral Nerves

• Nerves (PNS): Collections of axons outside CNS
  • Schwann Cells: Provide myelination for peripheral nerves
  • Oligodendrocytes: Provide myelination for CNS tracts

Examples

• Special Senses: Vision (eyes), Hearing (ears), Smell (nose), Taste (tongue), Balance (inner ear)
• General Senses: Touch (skin), Temperature (skin), Pain (skin and deeper tissues), Proprioception (joints, muscles)
• Voluntary Motor Response: Moving a limb
• Involuntary Motor Response: Heart rate, digestion

Conclusion

• The lecture highlights the differentiation between CNS and PNS, the functional and structural aspects of each, including the types of sensory and motor pathways, and the role of specific fibers and cell types in neuroanatomy.