Pathophysiology
Clinical meaning
The nervous system is divided into the central nervous system (CNS), consisting of the brain and spinal cord, and the peripheral nervous system (PNS), consisting of 12 pairs of cranial nerves and 31 pairs of spinal nerves. The brain is organized into the cerebrum (responsible for higher cognitive functions, voluntary movement, and sensory interpretation), the cerebellum (responsible for coordination, balance, and fine motor control), and the brainstem (which controls vital functions including heart rate, blood pressure, respiratory drive, and consciousness through the reticular activating system). The Glasgow Coma Scale (GCS) is the most widely used standardized tool for assessing level of consciousness, measuring three components: eye opening (1-4 points), verbal response (1-5 points), and motor response (1-6 points), with scores ranging from 3 (deep coma) to 15 (fully alert and oriented). A GCS score of 8 or below generally indicates severe neurological impairment and the inability to protect the airway. Level of consciousness is the most sensitive indicator of neurological change and the earliest sign of deterioration. The twelve cranial nerves control specific functions that can be assessed at the...