Fundamentals of Neuroanatomy

Aug 11, 2024

Neuroanatomy Lecture Notes

Overview

  • Basic concepts of the nervous system.
  • Divisions: Central Nervous System (CNS) and Peripheral Nervous System (PNS).
  • Components: Brain and spinal cord (CNS); sensory and motor nerves (PNS).

Central Nervous System (CNS)

  • Components: Brain and spinal cord.
  • Functions:
    • Collects information from the environment and body via sensory systems.
    • Processes, compares, and contrasts information with past experiences.
    • Stores sensory input and integrates new information with stored data.
    • Decides on motor responses and generates output.
  • Flow of Information: Sensory input goes to CNS -> CNS processes and makes decisions -> Motor output is generated.

Peripheral Nervous System (PNS)

  • Divisions: Sensory and motor parts.
  • Functions:
    • Takes sensory info from periphery to CNS.
    • Carries motor decisions from CNS to peripheral tissues.

Sensory System

  • Divisions: Special senses and general senses.
  • Special Senses: Elicited from specific body parts (eyes, nose, tongue, ears).
  • General Senses: Can be felt from multiple body parts (touch, temperature).
  • Somatic Sensations: From skin, subcutaneous tissue, locomotor system. Includes pain, temperature, touch, and proprioception.
  • Visceral Sensations: From internal organs; often result in dull pain, discomfort from distension, etc.

Motor System

  • Types of Motor Responses: Voluntary (somatic) and involuntary (autonomic).
  • Voluntary (Somatic): Controlled consciously (skeletal muscles).
  • Involuntary (Autonomic): Not under conscious control (smooth muscles, glandular secretions).
  • Autonomic Nervous System:
    • Sympathetic: Increases activity under stress (fight/flight response).
    • Parasympathetic: Dominates when relaxed (rest and digest).

Brain Anatomy

  • Divisions of the Brain:
    • Hindbrain (Rhombencephalon): Medulla, pons, cerebellum.
    • Midbrain (Mesencephalon): Central part of the brain.
    • Forebrain (Prosencephalon): Cerebral hemispheres (telencephalon) and deeper structures (diencephalon).
  • Gray Matter vs White Matter:
    • Gray Matter: Collections of neuronal cell bodies (cortex if on the surface, nucleus if deeper and surrounded by white matter).
    • White Matter: Bundles of axons connecting different parts of the CNS.
    • Tracts: Bundles of axons moving up and down (ascending and descending).
    • Commissural Fibers: Connect right and left parts of the brain.
    • Association Fibers: Connect front and back parts of the brain.
    • Reticular Formation: Network of mixed gray and white matter in the brainstem.

Neurons and Glial Cells

  • Neurons: Conduct electrochemical information (action potentials).
  • Glial Cells (Neuroglia): Support neurons.

Additional Concepts

  • Proprioception: Sense of body position, important for coordination and movement.
  • Conscious vs Unconscious Sensory Input: Some sensory information reaches conscious awareness (processed by the cerebral cortex), while other information does not.
  • Nerves vs Tracts:
    • Nerves: Collection of axons outside CNS.
    • Tracts: Collection of axons within CNS.
    • Myelination: Nerves are myelinated by Schwann cells; tracts by oligodendrocytes.

Diseases

  • Different diseases can affect either Schwann cells or oligodendrocytes, leading to demyelination and conduction problems in the PNS and/or CNS.

This is a summary of the key points and concepts covered in the lecture on basic neuroanatomy.