Overview of the Nervous System and Special Senses

Central Nervous System (CNS)

Comprises the brain and spinal cord.

Peripheral Nervous System (PNS)

Includes all other nerves outside the CNS.

Cerebrum

Consists of four lobes: frontal, temporal, parietal, and occipital.

Cerebellum

Responsible for learned body movement and equilibrium.

Diencephalon

Contains the thalamus and hypothalamus, processing sensory information.

Brain Stem

Includes the midbrain, pons, and medulla oblongata, involved in processing sensory information and vital functions.

Decussation

The term for paralysis from a stroke that presents with left facial paralysis and right-sided body paralysis.

Spinal Cord

Serves as a pathway for communication between the brain and the body, involved in both incoming and outgoing messages.

Reflexes

Un-thought responses to stimulus, transmitted from the spinal column.

Quadriplegia

Paralysis that can affect respiratory drive, occurring with injuries above C-5.

Paraplegia

Paralysis occurring with injuries below C-5.

Somatic Nervous System

Involves voluntary control and includes 12 pairs of cranial nerves and 31 pairs of spinal nerves.

Autonomic Nervous System

Involuntary control with two branches: sympathetic and parasympathetic.

Sympathetic Nervous System

Responsible for 'fight or flight' responses.

Parasympathetic Nervous System

Responsible for returning the body to a normal state.

Meninges

Three-layered membrane protecting the brain and spinal cord.

Cerebral Spinal Fluid (CSF)

Approximately 100 ml, provides protection from minor physical shocks.

Traumatic Brain Injuries (TBI)

Range from mild concussions to severe injuries like subdural and epidural hematomas.

Transient Ischemic Attack (TIA)

A temporary interruption of blood supply to the brain.

Cerebrovascular Accident (CVA) / Stroke

Deprivation of oxygen to an area of the brain due to blockage or rupture of a blood vessel.

Hemiparesis

Weakness on one side of the body.

Hemiplegia

Paralysis on one side of the body.

Aphasia

Loss of speech.

Dysphasia

Impaired speech.

Aneurysm

Localized dilation/bleeding of an artery in the brain.

Intracranial Pressure (ICP)

Normal ICP is 5-15 mm/hg; pressures above 15 mm/hg are considered elevated.

Systemic Degenerative Diseases

Include multiple sclerosis (demyelination), Parkinson's disease (decreased dopamine), Alzheimer's/Dementia (possibly micro-embolic strokes, brain atrophy), ALS (Lou Gehrig's), and Huntington's chorea. These are often linked to genetic anomalies.

Epilepsy

Characterized by petite mal and grand mal seizures, often caused by metabolic disorders or cerebral lesions.

Behavioral Disorders

Include anxiety disorders, OCD, phobias, mood disorders (depression, bipolar), and psychosis (schizophrenia).

Special Senses

The ability to perceive reality is crucial for attaining wisdom.

Five Senses

Touch (PNS), smell (Cranial nerve #1 - olfactory), taste (Cranial nerve #9 - glossopharyngeal), sight, and hearing.

Sense of Sight

The eye functions like a video camera, continuously transmitting light images to the brain via the nervous system.

Vision Control

Vision is controlled by Cranial nerve #2 (optic). Eye movement is controlled by Cranial nerves #3 (oculomotor), #4 (trochlear), and #6 (abducens).

Eye Layers

The eye has three layers: sclera, uveal tract (choroid, iris, ciliary body), and retina (containing light-sensitive rods and cones).

Common Eye Disorders

Include presbyopia (farsightedness), myopia (nearsightedness), astigmatism (refractive error), conjunctivitis (pink eye), keratitis (corneal inflammation), glaucoma (increased intraocular pressure), and cataract (cloudiness of the lens).

Sense of Hearing

The ear is responsible for both hearing and equilibrium.

Hearing Control

Hearing is controlled by Cranial nerve #8 (vestibulocochlear).

Ear Structure

The ear is divided into the outer ear (pinna, auditory canal, tympanic membrane), middle ear (malleus, incus, stapes), and inner ear (cochlea/labyrinth).

Hearing Disorders

Include deafness (unilateral or bilateral), conductive hearing loss (outer/middle ear), sensorineural hearing loss (nerve involvement), impacted cerumen (ear wax buildup), earaches (trauma or infection), Meniere's syndrome (inner ear disorder), and tinnitus (ringing in the ears).

CNS

Central nervous system.

CVA

Cerebrovascular accident.

ICP

Intracranial pressure.

PERRLA

Pupils equal, round, reactive to light and accommodation.

Todd Paralysis

Post seizure, transient focal neurological deficits that resembles a stroke.

Paresis

Partial or incomplete paralysis.

Babinski Reflex

a normal newborn reflex that involves the big toe extending upward and other toes fanning out when the sole of the foot is stroked