BS1060 - CNS 1 - 2025

Page 1: Introduction to the Central Nervous System

Overview of the CNS
- The Central Nervous System (CNS) includes the brain and spinal cord.
- It is vital for processing and integrating sensory information and coordinating bodily functions.
- Key components covered:
  - Meninges
  - Cerebrospinal Fluid
  - Blood-Brain Barrier
  - Focus on CNS Anatomy, particularly the Forebrain.

Aims
- To provide a comprehensive overview of the anatomical and functional organization of the human CNS.
General Facts about the Human Brain
- Average mass: ~1.5 kg (~2% of body mass).
- Consumes up to 20% of the body's total energy.
- Composed of:
  - Neurons: Approx. 86 billion
  - Non-neurons: Approx. 85 billion.

Main Axes in Neuroanatomy
- Rostral-Caudal: From front (rostral) to back (caudal).
- Dorsal-Ventral: From top (dorsal) to bottom (ventral).
Section Planes:
- Horizontal Plane: Divides the body into upper (superior) and lower (inferior) parts.
- Coronal Plane: Divides the body into front (anterior) and back (posterior) sections.
- Sagittal Plane: Divides the body into right and left parts.

Central Nervous System (CNS)
- Comprises the brain and spinal cord.
- Functionally divided into input and output systems:
  - Afferent Division: Carries sensory information to the CNS.
    - Includes sensory and visceral stimuli.
  - Efferent Division: Carries motor commands away from the CNS to various body parts.
    - Divided into somatic (voluntary) and autonomic (involuntary) systems:
      - Sympathetic and Parasympathetic nervous systems.

CNS Anatomy
- Brain and spinal cord are protected by:
  - Meninges
  - Blood-Brain Barrier
  - Surrounded by cerebrospinal fluid (CSF).
- The CNS protects the brain from:
  - Mechanical damage
  - Pathogens
  - Toxins.
- Key Function: To maintain a stable specialized environment (e.g., ionic composition and nutrition).