Introduction to the Structure of the Nervous System

The nervous system is divided into two main structural parts:

1. Central Nervous System (CNS)

• Components:
  • Brain
    • Made up of several parts:
      • Cerebrum: Largest part, divided into left and right cerebral hemispheres.
      • Brain Stem: Connects cerebrum to spinal cord; divided into:
        • Midbrain
        • Pons
        • Medulla Oblongata
      • Cerebellum: Located behind the brain stem.
    • Developmental Origins:
      • Forebrain (Prosencephalon): Develops into the cerebrum.
      • Midbrain (Mesencephalon): Remains as midbrain.
      • Hindbrain (Rhombencephalon): Develops into pons, medulla, and cerebellum.
  • Spinal Cord: Extends down the spine; involved in transmitting information between the brain and the rest of the body.

2. Peripheral Nervous System (PNS)

• Components:
  • Nerves: Long stringy structures carrying axons of neurons across the body.
  • Ganglia: Lumps attached to nerves containing somas of neurons.
• Functions:
  • Afferent Neurons: Carry information into the CNS.
  • Efferent Neurons: Carry information away from the CNS.
• Types of Nerves:
  • Cranial Nerves: Exit the skull; 12 pairs.
  • Spinal Nerves: Exit the spinal cord; 31 pairs.
  • Spinal Nerve Roots:
    • Back Roots: Carry afferent neurons.
    • Front Roots: Carry efferent neurons.

Distribution of Nerves

• Nerves branch repeatedly from proximal (near the center) to distal (far from the center) ends, becoming microscopic.
• Cranial and spinal nerves connect various parts of the body back to the CNS.

Visual Representations

• Diagrams were used to illustrate the brain, spinal cord, cranial nerves, and their connections.

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This lecture provided a broad overview of the nervous system's structure, explaining the central and peripheral nervous systems and how they relate to each other. Further details will be explored in subsequent lessons.