Nervous System Revision Sheet

1. 📌 Essentials

• The CNS includes the brain and spinal cord, protected by meninges.
• The brain is divided into cerebrum, cerebellum, and brainstem.
• The spinal cord extends from the foramen magnum to L1-L2, with 31 segments.
• Ventricular system produces and circulates cerebrospinal fluid (CSF).
• Major pathways: ascending (sensory) and descending (motor) tracts.
• Cranial nerves (12 pairs) have specific sensory, motor, or mixed functions.
• Spinal nerves (31 pairs) are mixed, with dorsal (sensory) and ventral (motor) roots.
• The autonomic nervous system has sympathetic and parasympathetic divisions.
• Meninges layers: dura mater, arachnoid mater, pia.
• Reflex arcs involve receptors, CNS processing, and motor effectors.

2. 🧩 Key Structures & Components

• Cerebrum — higher cognitive functions, voluntary movement.
• Cerebellum — coordination, balance, fine motor control.
• Brainstem — autonomic functions, cranial nerve nuclei.
• Spinal cord — transmits signals between brain and body.
• Ventricular system — lateral, third, and fourth ventricles; CSF production.
• Meninges — dura mater (outer), arachnoid mater (middle), pia mater (inner).
• Cranial nerves — 12 pairs, e.g., optic nerve (II), vagus nerve (X).
• Spinal nerves — 31 pairs, with dorsal (sensory) and ventral (motor) roots.
• Autonomic divisions — sympathetic (fight/flight), parasympathetic (rest/digest).

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