Neuroanatomy Basics

Overview of Nervous System Components

• Central Nervous System (CNS)

  • Comprises the brain and spinal cord.
  • Functions include:
    • Thermoregulation
    • Collects information from the environment through sensory systems.
    • Processes and integrates sensory information.
    • Generates motor responses.

• Peripheral Nervous System (PNS)

  • Divided into:
    • Sensory PNS: Transmits sensory information to CNS.
    • Motor PNS: Transmits motor commands from CNS to periphery.

Functions of Central Nervous System

1. Receiving Sensory Information:
   • Collects data from the environment via sensory input (e.g., visual, auditory).
2. Processing Information:
   • Compares current sensory data with stored memories.
3. Decision Making:
   • Determines response based on processed information.
4. Motor Responses:
   • Generates responses such as muscle movement or gland secretion.

Peripheral Nervous System Subdivisions

• Sensory Nerves: Convey information to the CNS.
• Motor Nerves: Convey commands from the CNS to peripheral tissues.

Types of Sensory Information

• Special Senses:
  • Specific to particular organs (e.g., vision, hearing).
• General Senses:
  • Can be elicited from multiple body parts (e.g., touch).
  • Subcategories:
    • Somatic Sensations: From skin and locomotor system (touch, pain, temperature).
    • Visceral Sensations: From internal organs (e.g., discomfort from cramps).

Proprioception

• The ability to sense body position and movement in space.
• Important for coordination and movement control.

Types of Motor Responses

• Voluntary Responses (Somatic):
  • Under conscious control (e.g., moving a hand).
• Involuntary Responses (Autonomic):
  • Not under conscious control (e.g., digestion, heart rate).

Autonomic Nervous System

• Divided into:
  • Sympathetic Nervous System: Activates fight or flight response.
  • Parasympathetic Nervous System: Promotes rest and digest state.

Brain Structure Overview

• Forebrain: Contains cerebral hemispheres.
• Midbrain: Connects forebrain and hindbrain.
• Hindbrain: Includes structures like the medulla, pons, and cerebellum.

Terminology of Brain Structures

• Gray Matter: Collection of neuronal cell bodies.
  • Cortex: Gray matter on the brain's surface.
  • Nucleus: Collection of neuron cell bodies surrounded by white matter.
• White Matter: Bundle of axons connecting different brain regions.

Classification of White Matter

1. Tracts:
   • Ascending (sensory) and descending (motor) pathways.
2. Commissural Fibers:
   • Connect the right and left hemispheres (e.g., corpus callosum).
3. Association Fibers:
   • Connect different parts of the same hemisphere.

Reticular Formation

• A network of gray and white matter in the brainstem, involved in various functions such as consciousness and sensory processing.

Important Distinctions

• Nerves vs. Tracts:
  • Nerves: Collections of axons outside CNS.
  • Tracts: Collections of axons within CNS.

Conclusion

• Understanding the structure and functions of the nervous system is essential for grasping neuroanatomy and its clinical implications.