Neuroanatomy Lecture Notes

Overview of Nervous System

• Two main components:
  1. Central Nervous System (CNS)
     • Includes brain and spinal cord.
  2. Peripheral Nervous System (PNS)
     • Connects CNS to the rest of the body.

Functions of Central Nervous System

• Basic Functions:
  • Collects information from the environment and body.
  • Receives sensory information from sensory systems.
  • Compares and contrasts new information with past experiences.
  • Integrates present and past experiences to generate motor responses.

Process of Information in CNS

1. Sensory Input:
   • Information collected via sensory nerves from the periphery.
2. Comparison:
   • New information is compared with previously stored data.
3. Integration:
   • Integration of new and old information to make decisions.
4. Motor Response:
   • Generates motor response, which may include voluntary movement or involuntary processes (e.g., gland secretion).

Peripheral Nervous System

• Divided into two parts:
  1. Motor Peripheral Nervous System
  2. Sensory Peripheral Nervous System
• Function:
  • Takes information from the periphery to the CNS and motor decisions from CNS to the periphery.

Types of Sensory and Motor Responses

• Sensory System:
  • Special Senses:
    • Elicited from specific body parts (e.g., vision, hearing, smell).
  • General Senses:
    • Elicited from multiple body parts (e.g., touch, temperature).
• Motor Responses:
  • Voluntary (Somatic):
    • Can be controlled (e.g., moving hand).
  • Involuntary (Autonomic):
    • Cannot be controlled (e.g., digestion, heart rate).

Types of Sensations

• Somatic Sensations:
  • Pain, temperature, touch, vibration, proprioception.
• Visceral Sensations:
  • Dull pain from internal organs (e.g., gastrointestinal discomfort).

Proprioception

• Awareness of body position and movement without visual input.
• Critical for coordination and movement.

Components of Central Nervous System

• Gray Matter:
  • Collection of neuronal cell bodies.
  • Found in CNS structures (e.g., cortex, nuclei).
• White Matter:
  • Collection of axons connecting different parts of the CNS.
  • Myelinated, giving it a lighter appearance.

Brain Structure

1. Forebrain (Prosencephalon)
   • Divided into Telencephalon (cerebral hemispheres) and Diencephalon (thalamus, hypothalamus).
2. Midbrain (Mesencephalon)
3. Hindbrain (Rhombencephalon)
   • Includes cerebellum, pons, and medulla oblongata.

Neurons and Glial Cells

• Neurons:
  • Main functional cells conducting information through action potentials.
• Neuroglial Cells:
  • Supportive cells in the nervous system.

Gray Matter vs. White Matter

• Gray Matter:
  • Contains neuronal cell bodies; involved in processing information.
• White Matter:
  • Contains axons; involved in transmission of information between different brain areas.

Nuclei vs. Cortex

• Cortex:
  • Gray matter exposed on brain surfaces.
• Nuclei:
  • Collections of gray matter deeper in the CNS, surrounded by white matter.

Types of White Matter Tracts

1. Ascending Tracts:
   • Carry sensory information upward to the brain.
2. Descending Tracts:
   • Carry motor information downward from the brain.
3. Commissural Fibers:
   • Connect right and left hemispheres (e.g., corpus callosum).
4. 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, including the regulation of consciousness and alertness.

Nerves vs. Tracts

• Nerves:
  • Collections of axons in the PNS.
• Tracts:
  • Collections of axons within the CNS.

Conclusion

• Understanding the distinctions between different parts of the nervous system, their functions, and their structures is crucial for studying neuroanatomy and neurophysiology.