2 - APP - Unit 3.1 - Nervous System Flashcards
The nervous system
Controls and coordinates the functions of the other systems of the body so they work harmoniously and efficiently.
Composed of: brain + spinal cord + peripheral nerves
The nervous system - Types of cells
- Neurons
- Neuroglia
The nervous system - Neurons
Responsible for most special functions attributed to the nervous system:
- sensing
- thinking
- remembering
- controlling muscle activity
- regulating glandular secretions
The nervous system - Neuroglia
Support, nurture and protect neurons and maintain homeostasis of the fluid that bathes neurons
Neurons & nerves - Neuron composition
A cell body
Its outgrowth of projections (=neuronal fibers)
Neurons & nerves - Types of neuronal fibers
- Numerous multi-branched dendrites that connect with other neurons to receive information
- A single Axon that conducts impulses away from the cell body
Neurons & nerves - Cell body
Stores energy and nutrients that are used by the cellular projections to receive and conduct nerve impulses throughout the body
Neurons & nerves - Synapse
Junction at which impulses are passed from one neuron to another
Neurons & nerves - Neurotransmitter
When an impulse reaches the end of an axon, a chemical neurotransmitter is released at the synapse that acts on the membrane of the receptive neuron to pass the impulse along.
Neurons & nerves - Neurons are classified according to…
… the direction in which they transmit nerve impulses and the type of information carried.
Neurons & nerves - 3 types/classifications of neurons
- Sensory neurons
- Motor neurons
- Interneurons
Neurons & nerves - Sensory neurons
AKA Afferent Neurons
Originate in the periphery of the body
Carry incoming information (impulses or messages from sense organs) to the brain & spinal cord where sensations of touch, cold, heat, sight, hearing, taste or pain are interpreted and experiences
Neurons & nerves - Motor neurons
AKA Efferent Neurons
Carry outgoing motor information (nerve impulses) from the brain/spinal cord to the muscles or glands that they control
Neurons & nerves - Interneurons
AKA Central or Connection neurons
Located in the brain and spinal cord
Carry impulses from one neuron to another
Neurons & nerves - Nerve cell bodies & fibers location
Almost all nerve cell bodies are contained in the brain and spinal cord
Fibers extend outward to make up the nerves
Neurons & nerves - Nerve
A group of neuronal fibers (axons and/or dendrites) found in the peripheral portions of the nervous system bundled together by connective tissue like the strands of a cable
Neurons & nerves - Myelin
Fatty insulating material wrapping individually the fibers found within the nerve
Divisions of the Nervous System - 2 divisions
- Central nervous system
- Peripheral nervous system
Divisions of the Nervous System - Central nervous system (CNS)
CNS = Brain + Spinal Cord
- incoming sensory information are integrated and correlated
- thoughts and emotions are generated
- memories are formed and stored
Originate in the CNS: most nerve impulses that stimulate muscles to contract & glands to secrete
CNS communicates with rest of the body through PNS
Divisions of the Nervous System - Brain
Principle nerve center
Body’s largest & most complex nerve tissue containing in excess of ten billion neurons and innumerable nerve fibers
Located in & protected by cranium
Controls sensations, muscles, glandular activity & the power to think and feel (emotions)
Divisions of the Nervous System - Brain - Diencephalon
2 parts:
- Thalamus - the “sensory brain”
- Hypothalamus - the principal link between endocrine and nervous systems
Divisions of the Nervous System - Brain - Cerebrum
Largest portion making up the front and top of the brain Presides over complex activities / mental activities as: - speech - sensation - communication - memory - reasoning - emotions
Divisions of the Nervous System - Brain - Cerebellum
Smaller part of the brain
Located below the cerebrum & at the back of the cranium
Helps maintain body balance, coordinates voluntary muscles & makes muscular movement smooth and graceful
Divisions of the Nervous System - Peripheral nervous system (PNS)
PNS = All the nerves that connect the central nervous system to the rest of the body
Includes cranial nerves, spinal nerves and their branches
Divisions of the Nervous System - Brain - Diencephalon -Thalamus
Provides the sense of touch / pressure, pain & temperature
Provides functions in emotions & memory
Divisions of the Nervous System - Brain - Diencephalon -Hypothalamus
Principal link between the endocrine & nervous system
Regulates the pituitary gland
Functions in rage & agression, controls normal body temperature, food intake, thirst & help maintain the waking state and sleep cycles
Divisions of the Nervous System - Brain - Brain Stem - Midbrain
Contains main nerve pathways connecting cerebrum & lower nervous system
Contains certain visual and auditory reflexes that coordinate head and eye movement with things seen and heard
Divisions of the Nervous System - Brain - Brain Stem - Pons
Located between midbrain & medulla oblongata
Relays nerve impulses:
- between cerebrum & medulla oblongata
- from cerebrum to cerebellum
Divisions of the Nervous System - Brain - Brain Stem - Medulla oblongata
Enlarged continuation of spinal cord extending from the foramen magnum to the pons
Connects the brain & the spinal cord
Regulate heart rate, rate and depth of respiration & tonicity of blood vessels (+ digestion ?)
Divisions of the Nervous System - Limbic system
AKA “emotional” brain
Ring of structures on the inner border of the cerebrum & floor of the diencephalons, encircling the brain stem
Functions in:
- emotional aspects of behavior related to survival
- Primary function in emotions: pleasure, pain, anger, rage, fear, sorrow, sexual feelings, docility & affection
- memory (hippocampus + portions of cerebrum)
Divisions of the Nervous System - Limbic system - Hippocampus
Portion of the limbic system
Works with portions of the cerebrum functions in memory
Divisions of the Nervous System - Spinal cord
Extends downwards from the brain
Housed in and protected by the vertebral column
31 segments, each being the site of attachement of a pair of spinal nerves.
Functions as:
- a conduction pathway for nerve impulses traveling to & from the brain
- a reflex center between incoming & outgoing peripheral nerve fibers
Divisions of the Nervous System - Types of connective tissues surrounding and protecting the brain and spinal cord nervous tissue
- Cranial bones
- Vertebrae
- Meninges
- Layer of cerebrospinal fluid
Divisions of the Nervous System - Meninges
3 connective tissue layers that encircle the brain and spinal cord:
- Dura mater
- Arachnoid layer
- Pia mater
Divisions of the Nervous System - Meninges - Dura mater
Most superficial layer and durable layer
Compose of very thick and strong connective tissue
Divisions of the Nervous System - Meninges - Arachnoid layer
Middle layer
Avascular covering
“Spider web” arrangement of delicate collagen fibers
Divisions of the Nervous System - Meninges - Pia mater
Innermost layer
Thin transparent connective tissue layer that adheres to the surface of the spinal cord and brain.
Contains many blood vessels that supply nutrients and oxygen to the brain & spinal cord
Divisions of the Nervous System - Cerebrospinal fluid (CSF)
Nourishes and protects brain and spinal cord against chemical & physical injury
…..;
To be completed
Divisions of the Nervous System - Cerebrospinal fluid (CSF)
Nourishes and protects the CNS (Central Nervous System = brain + spinal cord) against chemical & physical injury by acting as a shock absorber for the delicate nervous tissue.
Continuously circulates around the brain and spinal cord inside the subarachnoid space found between the arachnoid layer and pia mater.
Carries nutrients to the nerve tissue and carries waste away
Divisions of the Nervous System - Peripheral nervous system (PNS)
PNS = All the nerves that connect the central nervous system to the rest of the body
Includes cranial nerves, spinal nerves and their branches
Divisions of the Nervous System - Cranial nerves - Definition
12 cranial nerves
Connect directly to some part of the brain surface and pass through openings on the sides and base of the cranium
Divisions of the Nervous System - Cranial nerves - Classifications
- Motor
- Sensory
- Mixed nerves - containing both motor and sensory fibers
Divisions of the Nervous System - the 12 Cranial nerves
CN I. Olfactory nerve - Sense of smell
CN II. Optic nerve - Sense of sight
CN III. Oculomotor nerve - Controls eye movements
CN IV. Trochlear nerve - Controls eye movements
CN V. Trigeminal nerve - Controls face sensations & jaw movements. 3 branches: Mandibular branch / Maxilary Branch / Ophtalmic branch
CN VI. Abducent nerve - Sense of hearing
CN VII. Facial nerve - Controls facial muscles of expression & some neck muscles
CN VIII. Auditory Nerve - Sense of hearing
CN IX. Glossopharyngeal nerve - Sense of taste
CN X. Vagus nerve - Controls sensations & muscular movements relating to talking, heart action & digestion (longest cranial nerve - MBLEX)
CN XI. Spinal accessory nerve - Controls neck muscles movement (incl. trapezius & sternocleidomastoid)
CN XII. Hypoglossal nerve - Controls movement of the tongue
Divisions of the Nervous System - Spinal nerves - Definition
31 pairs of spinal nerves emerge from the spinal cord
All mixed nerves (contain sensory and motor nerve fibers) to provide 2-way communication between CNS and body
Divisions of the Nervous System - Spinal nerves - Emergence
Spinal nerves emerge from the spinal cord in the following order:
- 8 pairs attached to cervical segments
- 12 pairs attached to thoracic segments
- 5 pairs attached to lumbar segments
- 5 pairs attached to sacrospinal segments
- 1 pair attached to coccygeal segment
Divisions of the Nervous System - Spinal nerves - Branching
After spinal nerves exit from spinal cord segments they branch to form many peripheral nerves of the truck & limbs
Divisions of the Nervous System - Spinal nerves - Plexus
Neuronal fibers from several spinal nerves can reorganize to form a single peripheral nerve, which can be seen as a network of intersecting or “braided” branches
Divisions of the Nervous System - Spinal nerves - 4 Plexus
- Cervical plexus
- Brachial plexus
- Lumbar plexus
- Sacral plexus
Divisions of the Nervous System - Spinal nerves - Plexus - Cervical plexus
Four upper cervical nerves
Supplies sensation for the skin and motor control for the muscles of the head, neck & shoulders
Divisions of the Nervous System - Spinal nerves - Plexus - Brachial plexus
Four lower cervical nerves + the first pair of thoracic nerves
Controls movements of the arms
Provide sensory & motor control for the muscles, skin & organs of the thorax
Divisions of the Nervous System - Spinal nerves - Plexus - Lumbar plexus
First four lumbar nerves
Supply sensory & motor control for the skin, abdominal organs, hip, thigh, knee & leg
Divisions of the Nervous System - Spinal nerves - Plexus - Sacral plexus
4th + 5th lumbar nerves & 1st to 4th sacral nerves
The spinal nerves that for the sacral plexus divide and emerge to form several nerves including the sciatic nerve
Divisions of the Nervous System - Spinal nerves - Sacral plexus - Sciatic nerve
The largest and longest nerve in the body
Divisions of the Nervous System - Cranial nerves - 3 branches of Trigeminal nerve
- Mandibular branch
- Maxilary Branch
- Ophtalmic branch
= trigeminal ganglion ?
Physiology of the Central Nervous System - 3 Cerebral regions
- Sensory areas - Receive and interpret sensory impulses
- Motor areas - Control muscular movement
- Association areas - Deal with more complex integrative functions
Physiology of the Central Nervous System - Sensory areas
Receive and interpret sensory impulses
Sensory input to the cerebral cortex flows mainly to the posterior half of the cerebral hemispheres.
In the cortex: primary sensory areas have most direct connections with peripheral sensory receptors
Physiology of the Central Nervous System - Sensory receptors - Classification by location
- Exteroceptors
- Interoceptors or Visceroceptors
- Proprioceptors
Physiology of the Central Nervous System - Sensory receptors - Exteroceptors
Located at or near the surface of the body.
Provide information about the external environment.
Sensitive to stimuli outside of the body and transmit sensations (hearing, vision, smell, taste, touch, pressure, vibration, temperature & pain).
Physiology of the Central Nervous System - Sensory receptors - Interoceptors or Visceroceptors
Located in blood vessels and viscera.
Provide information about the internal environment.
Sensations arise from within the body and often do not reach conscious perception
Physiology of the Central Nervous System - Sensory receptors - Proprioceptors
Located in muscles, tendons, joints & internal ear
Provide information about body position and movement
Physiology of the Central Nervous System - Sensory receptors - Classification by type of stimuli
- Mechanoreceptors - detect mechanical pressure or stretching
- Thermoreceptors - detect changes in temperature
- Nociceptors - detect pain
- Photoreceptors - detect light that strikes the retina
- Chemoreceptors - detect chemicals in the mouth, nose and body fluids
Physiology of the Central Nervous System - Motor areas
Control muscular movement
Motor output from cerebral cortex flows mainly from anterior portion of the cerebral hemisphere.
Primary motor area controls voluntary contractions of specific muscles or group of muscles
Physiology of the Central Nervous System - Association areas
Deal with more complex integrative functions (memory, emotions, reasoning, will, judgment, personality traits & intelligence)
Physiology of the Peripheral Nervous System
- Somatic nervous system - involves nerves connecting the CNS to the voluntary muscles and skin
- Autonomic nervous system (ANS) - connects the CNS to the visceral organs (heart, blood vessels, glands & intestines) - autonomic = self-governing.
Physiology of the Peripheral Nervous System - Autonomic nervous system (ANS) - 2 parts
- Sympathetic nervous system
- Parasympathetic nervous system
Physiology of the Peripheral Nervous System - Sympathetic nervous system
Nerves originate in the thoracic and lumbar portions of spinal cord (T1 to L2)
Enter double chain of small masses of neurons (=ganglia)
Prepares the body for energy expending, stressful or emergency situations.
Rapid response to stimulation:
- increased respiration
- dilated pupils
- increased heart rate
- cardiac output
- dilated blood vessels
- liver glucose production increased for energy
- increased mental activity
- production of adrenal hormone
Physiology of the Peripheral Nervous System - Ganglia
Double chain of small masses of neurons
Physiology of the Peripheral Nervous System - Parasympathetic nervous system
Balances action of the sympathetic system.
Conserve energy & reverse the action of the sympathetic division.
Reflexes & Reflex Arcs - Reflex
Simple form of nervous activity that includes a sensory or motor nerve
Automatic, unconscious, involuntary response to stimulus.
Expl:
- body activities: sneezing, coughing or swallowing
- involuntary activities: heart rate, breathing rate or blood pressure
Reflexes & Reflex Arcs - Reflex arc
Nerve pathway of a reflex
5 components:
- Receptor
- Sensory neuron
- Integrating center
- Motor neuron
- Effector
Reflexes & Reflex Arcs - Reflex arc - Receptor
Distal end of the sensory neuron or an associated sensory structure
Responds to specific stimulus
Reflexes & Reflex Arcs - Reflex arc - Sensory neuron
Located in the spinal cord or brai stem
Carries stimulus impulse to the integrating center
Nerve impulses are conducted from receptor to sensory neuron.
Reflexes & Reflex Arcs - Reflex arc - Integrating center
Processes the reflex/stimulus impulse
For simplest type of reflex, integrating center is a single synapse, between sensory neuron & motor neuron
Reflexes & Reflex Arcs - Reflex arc - Motor neuron
Impulses triggered by integrating center propagate along motor neuron to body part that will respond
Carries the reflex stimulus out to the tissue that expresses the reflex
Reflexes & Reflex Arcs - Reflex arc - Effector
Body part that responds to motor impulse
Expl: muscle, gland
Its action = reflex
Reflexes & Reflex Arcs - Tendon reflex
Expl: knee jerk
Simple reflex involving two neurons that pass into and out of the spinal cord without influencing any other nerve centers.
Reflexes & Reflex Arcs - Withdrawal reflex
Flexor reflex
Polysynaptic reflex occuring when a person touches something sharp or hot and immediately pulls away preventing excessive injury.
Proprioception
Ability to sense body position & movement.
Sensory & motor nerve activity provide information (state of contraction, muscle position) by sensing tissue distortion, compression, twist.
Helps prevent joint and muscles injuries from excessive stretches or contractions
Helps in coordination of smooth & accurate motion.
Disorders of the Central Nervous System - Aneurysm
Ballooning out of an artery, accompanied by thinning arterial wall, caused by weakening of blood vessel.
Pulsates with each heartbeat.
Symptoms: pain & pressure (or none)
Most common: aorta
DO NOT massage the area
Arteries
Thick muscular blood vessel that carries blood away from the heart
Arteries are located deep in the body
Veins
Superficial, thin, weaker than arteries
Blood vessels that carry blood towards the heart
Located superficially in the body
Atherosclerosis vs Arteriosclerosis
Atherosclerosis: Fatty plaquing vessel disease
Arteriosclerosis: Hardening of the arteries caused by hypertension
Disorders of the Central Nervous System - Alzheimer disease (AD)
Disabling neurological disorder
- initially: trouble remembering recent events
- then: confused and forgetful (repeating questions, getting lost on familiar places)
- disorientation grows, memories past events disappear, paranoia, hallucination, violent changes in mood
Lose ability to: read, write, talk, eat or walk
Massage: full body not recommended - hand or scalp only
Disorders of the Central Nervous System - Cerebral palsy (CP)
Motor disorders resulting in muscular incoordination and loss of muscle control.
Irreversible but does not worsen with time
Cause: damage of motor areas of the brain during fetal life, birth or infancy (mother with german measles during 1st trimester, fetus radiation, temporary lack of oxygen during birth or hydrocephalus during infancy) 2/1000 children
70%: mentally retarded. Inability to speak or hear well.
Disorders of the Central Nervous System - Cerebrovascular accident (CVA)
AKA Stroke
Most common brain disorder
Brain tissue death due to a lack of blood supply.
- Ischemia - a reduction in blood supply
- Infarcion - tissue death dus to a lack of blood supply (cerebral infarction)
Common causes:
- Intracerebral hemorrhage (from blood vessel in the pia mater or brain)
- Emboli (blood clots)
- Atherosclerosis of the cerebral arteries (formation of cholesterol-containing plaques that block blood flow) of the cerebral arteries
Disorders of the Central Nervous System - Cerebrovascular accident (CVA) - 2 types
- Ischemic - Most common type - A reduction in blood supply (commonly from blood clot)
- Hemorrhagic - Rupture of a blood vessel in the brain
Disorders of the Central Nervous System - Blood clots - 2 types
- Embolus - Blood clot that is floating
2. Thrombus - blood clot that is stuck
Disorders of the Central Nervous System - Concussion
Results from the stunning, damaging or shattering effects of a hard blow (especially jarring brain injury resulting in disturbance of cerebral function & sometimes permanent brain damage)
> Outside force impact skull with force
then brain overcomes the cerebrospinal fluid cushion
then meninges crushed between the brain & the cranial bones of the skull.
Disorders of the Central Nervous System - Subdural hematoma
Bruise under the dura, leading to inflammation & swelling under the dural covering leading tho cerebral compromise
Significant side effect of concussion
Disorders of the Central Nervous System - Dementia
Mental disorder
Permanent or progressive general loss of intellectual abilities (impairment of memory, judgment or abstract thinking, change of personality)
Most common cause: Alzheimer’s disease
Disorders of the Central Nervous System - Depression
Psychoneurotic or psychotic disorder
Marked by: sadness, inactivity, changes in eating/sleeping habits, difficulty with thinking/concentration & hopeless - sometimes suicidal thoughts or attempt
Disorders of the Central Nervous System - Dyslexia
Impairment of the brain’s ability to translate images received from the eye into understandable language.
Difficulty to process words and symbols
Not related to basic intellectual capacity
Disorders of the Central Nervous System - Encephalitis
Acute brain inflammation
Cause: direct attack by viruses or by an allergic reaction to many of the viruses normally harmless to the central nervous system, or trauma.
Disorders of the Central Nervous System - Encephalitis - Encephalomyelitis
Inflammation of the brain AND spinal cord
Disorders of the Central Nervous System - Headache
One of the most common human afflictions
May be caused by:
- brain tumors;
- blood vessel abnormalities;
- brain or meninges inflammation;
- oxygen supply decrease in the brain;
- brain cells damages;
- eyes, ears, nose and sinuses infections
Most require no treatment
Massage therapy alleviate many causes of headache
Disorders of the Central Nervous System - Headache - 3 types
[Cluster headaches]
- Severe unilateral pain in the eye or temple
- Tends to recur in series of attacks
[Migraine headhaches]
- Recurrent severe headaches - usually unilateral
- Often accompanied with nausea & vomiting, then sleep
- Tends to occur in more than one family member (uncertain origin)
[Tension headaches]
- Most common
- Associated with stress, fatigue & anxiety
- Classically occur in occipital & temporal muscles
Disorders of the Central Nervous System - Meningitis
Acute inflammation of the meninges (pia and arachnoid matter around brain and spinal cord)
Cause: Often secondary infection due to bacteria (from middle ear, upper respiratory tract, lungs, sinuses) or virus (polio or mumps)
Symptoms: Present with severe headache, stiff neck, high fever, chills, delirium ad often convulsion or even coma
Diagnosis: spinal tap or lumbar puncture
Treatment: Antibiotic usually effective.
Untreated: permanent brain damages, possible: blindness, deafness, retardation, paralysis
Disorders of the Central Nervous System - Multiple sclerosis
Autoimmune disorder
Muscle weakness and loss of coordination and balance
Caused by the breakdown of myelin sheath (fatty material that covers nerve fibers) which inhibits nerve conduction
Symptoms: muscle weakness, loss of coordination & balance
Speech & vision affected
Disease progress varies with remission and progressions periods
No cure
Massage/physical/psychological therapy: counter effects
Disorders of the Central Nervous System - Parkinson’s disease
Degeneration of brain tissues responsible of regulation of certain body movements
Lack of proper production of dopamine (neurotransmitter)
Develops late in life.
Characterized by tremors & shaking (esp. hands)
Muscle stiffen, movement slows & become more deliberate as postural reflexes are lost
Massage relieves tension & relax muscles (esp. shoulders, neck, legs)
Disorders of the Central Nervous System - Schizophrenia
Psychotic disorder
Loss of contact with the environment
Noticeable deterioration in the level of functioning in everyday life
Disintegration of personality expressed by a disorder of feelings, thoughts (as in delusions), perceptions (as in hallucination) and behavior.
Disorders of the Central Nervous System - Transient ischemic attack (TIA)
Episode of temporary cerebral dysfunction caused by impaired blood flow to the brain
Symptoms:
- dizziness, weakness, numbness, paralysis in a limb of in half of the body;
- drooping of one side of the face;
- headache, slurred speech or difficulty to understand speech;
- potential loss of vision or double vision
Sometimes: nausea, vomiting
Lasts a few minutes - rarely as long as 24hrs
No persistent neurologic deficits
Disorders of the Central Nervous System - Causes of spinal cord damages by compression
Causes include
- tumor within or adjacent to spinal cord
- herniated intervertebral discs
- blood clots
- penetrating wounds caused by projectile fragments
Other traumatic event such as automobile accidents
Disorders of the Central Nervous System - Paralysis
Total loss of voluntary motor function that results from damage to nervous or muscle tissue
Disorders of the Central Nervous System - Paralysis - Classification (x5)
[Monoplegia] - mono=one
Paralysis of one extremity only
[Diplegia] - di=two
Paralysis of both upper extremities or both lower extremities
[Paraplegia] - para=beyond
Paralysis of both lower extremities
[Hemiplegia] - hemi=half
Paralysis of the upper extremity, trunka nd lower extremity on one side of the body
[Quadriplegia] - quad=four
Paralysis of the two upper and two lower extremities
Disorders of the Peripheral Nervous System - Bell’s Palsy
Paralysis of one side of the face.
Cranial Nerve VII (facial nerve) disfunction
Can present sensory disfunction
Cause: trauma, emotional stress or infection
Symptoms: eye does not close properly, mouth droops, numbness on affected side
> usually disappear within a few weeks/months, with little residual effects
Disorders of the Peripheral Nervous System - Carpal tunnel syndrome
Better described as median nerve entrapment
Tendons and nerves pass from forearm to hand and fingers through a tight canal/”tunnel” at the base of the palm.
Cause: repetitive movement of the wrist in which hands are held in an unusual position.
Symptoms: Swelling (edema) around the carpal tunnel pressures the nerve.
Abnormal sensations, pain & weakness in the palm of the hand
Disorders of the Peripheral Nervous System - Tarsal tunnel syndrome
Similar to carpal tunnel syndrome
Caused by compression of the posterior tibial nerve
Symptoms of pain or paresthesia over the sole of the foot
Disorders of the Peripheral Nervous System - Paresthesia
Abnormal sensations
Pins & needles “crawling” of the skin, vibrations
Disorders of the Peripheral Nervous System - Hyperesthesia
Abnormal increase in sensitivity
Disorders of the Peripheral Nervous System - Hypoesthesia
Abnormal decrease in sensitivity
Disorders of the Peripheral Nervous System - Anesthesia
A total lack of sensation (numbness)
Disorders of the Peripheral Nervous System - Menieres’s Disease
Recurrent vertigo (dizziness) with ringing in the ears (tinnitus) and deafness
Usual causative agent: Dysfunction of the semi-circular canals in the inner ear
Disorders of the Peripheral Nervous System - Neuritis
Inflammation of a nerve or a nerve trunk
Symptoms: severe pain, hypersensitivity (hyperesthesia), loss of sensation (anesthesia), muscular atrophy, weakness & abnormal sensations: tingling, burning, crawling of the skin (paresthesia)
Cause: infection, chemical, other condition as chronic alcoholism (in that case: lack of vitamin B or improper diet)
Disorders of the Peripheral Nervous System - Poliomyelitis (=Polio)
Viral infection that damages the motor neurons of the medulla oblangata and spinal cord causing paralysis of the related muscle tissues
Crippling or deadly.
Early detection minimize devastating effects
Symptoms: fever, gastrointestinal discomfort, stiff neck & headache
Salk & Sabin vaccines nearly eradicated the disease
Disorders of the Peripheral Nervous System - Sciatica
Inflammation or injury of the sciatic nerve and its branches.
Presents with pain, abnormal sensations and weakness from the back, pelvis and entire lower extremities
Most common cause: tight piriformis muscle
Disorders of the Peripheral Nervous System - Shingles
Acute inflammation of a nerve trunk by varicella zoster virus (same that causes Chicken pox)
Symptoms: band of pain around torso and a rash with water blisters that erupt in a confined area on one side of the trunk.
Cause: an exposure to herpes or chicken pox, a reaction to medication, a trauma
Massage: contraindicated (risk of infection + really painful)
