The Nervous System

Brain (encephal/o): Protected by skull and meninges

Cerebrum: Largest part; divided into 4 lobes:

Cerebellum: Coordination, balance, fine motor

Brainstem: Midbrain, pons, medulla oblongata

Diencephalon: Thalamus (relay station), Hypothalamus (homeostasis, ANS, hormones)

Spinal Cord: Extends from foramen magnum to L1–L2; contains ascending (sensory) and descending (motor) tracts

Somatic NS: Voluntary; controls skeletal muscles; 31 pairs of spinal nerves + 12 cranial nerves

Autonomic NS: Involuntary; controls smooth muscle, cardiac muscle, glands

12 Cranial Nerves (mnemonics: "Oh, Oh, Oh, To Touch And Feel Very Good Velvet — Absolutely Heavenly"):

I Olfactory, II Optic, III Oculomotor, IV Trochlear, V Trigeminal, VI Abducens, VII Facial, VIII Vestibulocochlear, IX Glossopharyngeal, X Vagus, XI Accessory, XII Hypoglossal

Stroke (CVA — Cerebrovascular Accident):

Epilepsy/Seizures: Abnormal electrical discharges in brain

Multiple Sclerosis (MS): Autoimmune demyelination → muscle weakness, vision problems, fatigue

Parkinson's Disease: Degeneration of dopaminergic neurons in substantia nigra → tremor, rigidity, bradykinesia

Alzheimer's Disease: Progressive dementia; amyloid plaques and neurofibrillary tangles

Meningitis: Bacterial (Neisseria meningitidis) — emergency; viral (most common)

Guillain-Barré Syndrome: Ascending paralysis after infection; autoimmune attack on peripheral nerves

CT scan of head: First-line for stroke — rules out hemorrhage quickly

MRI brain/spine: Detailed soft tissue; shows MS plaques, tumors, strokes

EEG (Electroencephalogram): Records brain electrical activity; diagnoses epilepsy

Lumbar puncture (LP/spinal tap): CSF sample; diagnoses meningitis, MS, subarachnoid hemorrhage

EMG/Nerve conduction: Evaluate peripheral nerve and muscle function

Neurological exam: Level of consciousness (GCS), cranial nerves, motor/sensory, reflexes, coordination