Chapter 24: NEURO Flashcards
What does the PNS include?
nerve fibers outside the brain and spinal cord
What is the outer layer of the nerve cell bodies?
cerebral cortex aka gray matter that lacks myelin
What is myelin?
white insulation on the axon that increases the conduction velocity of nerve impulses
What is the functions of the cerebral cortex?
- center for humans highest functions
- governing thought
- memory
- reasoning
- sensation
- voluntary movements
Which hemisphere is most dominant in the cerebrum?
left hemisphere (including those who are left handed)
What are the 4 lobes of each hemisphere?
- frontal (personality, behavior, emotions and intellect)
- parietal (center for sensation)
- temporal (hearing, taste and smell)
- occipital (visual receptor center)
What initiates voluntary movement?
the precentral gyrus of the frontal lobe
What area of the brain is associated with language comprehension?
wernickes area (when damaged in the dominant hemisphere, receptive aphasia results)
What area of the brain mediates motor speech?
brocas area (when damaged in dominant hemisphere expressive aphasia results and the person cant talk)
What is the basal ganglia?
large bands of gray matter within the 2 cerebral hemispheres that help to initiate/coordinate movement and control automatic associated movements of the body
What is the thalamus?
main relay station where the synapses is formed that is crucial to human emotion and creativity
What is the hypothalamus?
major respiratory center with basic vital functions (temp, HR, sex drive, appetite, BP, etc) and coordinator of ANS activity and response
What is the cerebellum?
located under the occipital lobe; concerned with motor coordination of voluntary movements, equilibrium and muscle tone (coordinates and smooths movement)
What is the brainstem?
central core of the brain consisting of mostly nerve fibers (CN 3-12 originate here) with the following 3 area:
1. midbrain: most anterior part with basic tubular structure of the spinal cord; merges into thalamus and hypothalamus & contains many motor neurons/tracts
- pons: contains ascending/descending motor tracts and 2 respiratory centers that coordinate with main respiratory center in the medulla
- medulla: continuation of spinal cord with vital autonomic centers and nuclei for CN 8-12
What is the spinal cord?
connects the brain to the spinal nerves and mediates reflexes of posture control, urination, and pain response; the lumbar cistern is inside this space and is the favored spot to withdraw samples of cerebrospinal fluid (CSF)
What is crossed representation?
a notable feature of the nerve tracts with the left cerebral cortex receiving sensory info. from and controls motor function to the right side of the body and the right cerebral cortex interacts with the left side of the body
How does sensation travel?
afferent fibers in the peripheral nerve > posterior (dorsal) root > spinal cord (where it takes 1 of 2 routes: anterolateral (spinothalamic tract) or the posterior (dorsal) columns
What tract transmits the sensations of pain, temperature, itch and crude touch?
anterolateral tract (spinothalamic tract)
What does the posterior (dorsal) columns conduct?
sensations of position (proprioception: w/o looking you know where your body parts are in space/relation to one another), vibration and finely localized touch (sterognosis: w/o looking you can identify familiar objects by touch)?
What organs are absent from the brain map?
- heart
- liver
- spleen
- no felt image: organs experience referred pain and pain is felt by proxy by other body parts with a felt image *
Where is pain in the heart felt?
- chest
- shoulder
- left arm
Where is pain in the spleen felt?
- top of the left shoulder
What do corticospinal fibers mediate?
voluntary movement, particularly very skilled, discrete and purposeful movement such as writing
What is the extrapyramidal tracts?
include all motor nerve fibers from the motor cortex, basal ganglia, brainstem, and spinal cord that are outside the pyramidal tract; it maintains muscles tone and controls body movements (ex: walking)
What are the upper motor neurons?
complex; can influence/modify the lower motor neurons and are located within the CNS. They convey impulses from motor area of the cerebral cortex to the lower motor neurons in the anterior horn cells of the spine (ex: cospinal, corticobulbar, extrapyramidal tracts)
What are some examples of UMN diseases?
- stroke
- cerebral palsy
- MS
What are lower motor neurons?
located in the PNS; last pathways that funnels neural signals and provides the last direct contact with the muscles (ex: CN and spinal nerves of the PNS)
What are some examples of LMN diseases?
- bell palsy (CN 7)
- spinal cord lesions
- poliomyelitis
How does the PNS carry nerve input?
to the CNS via sensory afferent fibers and deliver output from the CNS via the efferent fibers (nerves = bundle of fibers outside the CNS)
What are reflexes?
defense mechanisms of the NS that are involuntary, operate below LOC control and permit a quick reaction to painful/damaging situations. reflexes also help body maintain balance and muscle tone
What are the 3 types of reflexes?
- stretch/DTR (myotatic: knee jerk)
- superficial (cutaneous: plantar reflex)
- visceral (organic: pupillary response to light/accommodation)
What are the 12 CNs (LMNs that enter/exit the brain rather than the spinal cord)?
- olfactory (sensory: fxn = smell)
- optic (sensory: fxn = vision)
- oculomotor (mixed: fxn = EOM, opening of eyelids, pupil constriction/dilation, lens shape)
- trochlear (motor: fxn = down/inward movement of the eye)
- trigeminal (mixed: fxn = motor: muscles of mastication and sensory: sensation of the face/scalp, cornea, mucous membranes of mouth/nose)
- abducens (motor: fxn = lateral movement of the eyes)
- facial (mixed: fxn = motor: facial muscles, close eyes, labial speech, close mouth; sensory: taste; parasympathetic: saliva and tear secretion)
- acoustic (sensory: fxn = hearing and equilibrium)
- glossopharyngeal (mixed: fxn = motor: pharynx (phonation/swallowing), sensory: taste and gag reflex, parasympathetic: parotid gland, carotid reflex)
- vagus (sensory: fxn = motor: pharynx and larynx (talking/swallowing), sensory: general sensation from carotid body, sinus, pharynx and viscera; parasympathetic: carotid reflex)
- spinal (motor: fxn = movement of trapezius and sternomastoid muscles)
- hypoglossal (motor: fxn = movement of tongue )
* primarily supply head and neck except the vagus nerve *
Where do CNs 1 and 2 extend from?
cerebrum
Where do CNs 3-12 extend from?
midbrain and brainstem
What is dermal segmentation and a dermatome?
dermal segmentation: the cutaneous distribution of the various spinal nerves
dermatome: a circumscribed skin area that is supplied from one spinal cord segment via a particular spinal nerve (if one never is damaged, sensations can be transmitted by the nerve above or below)
What are the dermatome segments?
- thumb, middle finger and 5th finger = C6, C7 and C8
- axilla = T1
- nipple = T4
- umbilicus = T10
- groin = L1
- knee = L4
What is the difference between the somatic fibers and autonomic fibers?
somatic innervate the skeletal (voluntary muscles) and the autonomic innervates smooth (involuntary muscles), cardiac muscle, glands and unconscious activity; overall function of the autonomic system is to maintain homeostasis
The aging adult:
- general atrophy w/steady loss of neuron structure in the brain/spinal cord –> dec. in weight/volume with a thinning of cerebral cortex, reduced subcortical brain structures and expansion of the ventricles
- neural loss –> loss of muscle bulk (esp. in hands), muscle tone in the face, neck and around the spine, dec. muscle strength, impaired fine coordination/agility, loss of vibratory sense at the ankle, dec/absent achilles reflex, loss of position sense at big toe, pupillary miosis, irregular pupil shape/dec pupillary reflexes
- reductions in brain volume is normal in healthy aging
- velocity of nerve conduction dec. b/w 5%-10% –> slower reaction time
- inc. delay at synapse –> longer travel time for impulse –> touch, pain sensation, taste and smell are diminished
- slower movement (motor)
- muscle strength/agility decrease (general dec. in muscle bulk that is more evident in the dorsal hand muscles which often look wasted)
- muscle tremors occur in the hands, head, jaw and possible repetitive facial grimacing
- progressive dec. in cerebral perfusion and O2 consumption –> dizziness/loss of balance with position change
- dec. of smell bilaterally
- grip should remain relatively good
- difficulty performing rapid alternating movements and tactile function is impaired
- plantar reflex may be absent or hard to interpret
Culture and genetics:
- stroke: 5th leading COD in USA –> interruption of blood flow to the brain (more AA, Indians, and Asians die from strokes at a younger age)
- USA southeast region is called the stroke belt d/t high stroke mortality (more in NC, SC and GA = buckle region)
- 1.9 M neurons die/min during an acute stroke
- AA at higher risk of strokes d/t high BP, uncontrolled BP and suboptimal control
- metabolic syndrome is more prevalent amongst Mexicans –> inc. r/f stroke
- mexican and asian men less likely to use EMS and black women less likely to use EMS than white women
This results from a direct blow that causes rotation of the brain inside the skull and shear injury
concussion
This is a sudden loss of strength, a temporary LOC caused by lack of cerebral perfusion
syncope
This is rotational spinning caused by neurological disease in the vestibular apparatus in the ear or the vestibular nuclei in the brainstem
vertigo
This occurs with epilepsy, a paroxysmal disease characterized by altered or LOC, involuntary muscle movements and sensory disturbances
seizures
What is aura?
a subjective sensation that precedes a seizure; it could be auditory, visual or motor
What is a tremor?
Involuntary shaking, vibrating or trembling
What is paresis?
partial or incomplete paralysis
What is paralysis?
a total loss of motor function caused by a lesion in the neurologic or muscular system or loss of sensory innervation
This is the inability to control the distance, power and speed of a muscular action
dysmetria
This is an abnormal burning/tingling sensation
parathesia
This is when a pt has a hard time forming words
dysarthria
This is when a pt has a hard time with language comprehension/expression
dysphasia
What is micturition syncope?
feeling faint while standing to urinate at night
What occurs with early AD?
memory loss and cognitive decline (sometimes confused w/normal cognitive decline of aging)
What is senile tremors and what relieves them?
intention tremor of hands, head nodding and tongue protrusion; alcohol (but not recommended)
What are some abnormal findings for CN 1?
- occluded air passages w/upper respiratory infxn or sinusitis
- anosmia (dec/loss of smell bilaterally d/t smoking, allergic rhinitis and cocaine use
- unilateral loss of smell in the absence of nasal disease is neurogenic anosmia (head trauma, brain lesion, etc.)
What are some abnormal findings for CN 2?
- visual field loss
- papilledema with inc. intracranial pressure
- optic atrophy
- defect in peripheral vision (hemianopsia)
What are some abnormal findings for CN 3, 4 and 6?
- ptosis (drooping): occurs w/myasthenia gravis, dysfunction of CN III or horner syndrome
- inc. intracranial pressure that causes sudden, unilateral, dilated and nonreactive pupils
- strabismus: deviated gaze or limited movement
- nystagmus: occurs w/disease of the vestibular system, cerebellum or brainstem
- diplopia on lateral gaze
What are some abnormal findings for CN 5?
- dec. strength on one or both sides
- asymmetry in jaw movement
- pain w/clenching of teeth
- unilateral weakness occurs with lesion of the pons and cancer to skull
- dec/unequal sensation (hemiparesis and aphasia often associated)
- sensory function test using a cotton swab to the ophthalmic, maxillary and mandibular: have pt say “now” when sensation is felt *
What are some abnormal findings for CN 7?
- muscle weakness: flattening of the nasolabial fold, drooping of one side of the face, lower eyelid sagging and escape of air from only one cheek when pressed in
- loss of movement and asymmetry of movement occur with both CNS lesions and PNS lesions
What are some abnormal findings for CN 9 and 10?
- absence or asymmetry of soft palate movement or tonsillar pillar movement
- after a stoke r/f aspiration increases
- hoarse or brassy voice occurs with vocal cord dysfunction; nasal twang occurs with weakness of soft palate
What are some abnormal findings for CN 11?
- atrophy
- muscle weakness or paralysis w/a stroke or following injury to the peripheral nerve
What are some abnormal findings for CN 12?
- atrophy/fasciculations
- tongue deviates to side when stroke affects the hypoglossal nerve
- light, tight, dynamite *
How should you measure muscle size and what is considered a difference in sizes that are not signficant?
measure in cm; a difference of < 1 cm is not significant
What are some abnormal findings for muscles and strength?
- atrophy: small muscle with a wasted appearance; occurs w/ disuse, LMN diseases, injury
- hypertrophy: increased size and strength; occurring w/isometric exercise
- paresis or weakness is diminished strength; paralysis or plegia is absence of strength
- flaccidity: dec. resistance/muscle tone, hypotonia occur with peripheral weakness; limb feels like rag doll
- spasticity and rigidity: types of inc. resistance occurring w/central weakness (hypertonia)
The finger-nose-finger test is testing for what?
cerebellar function
abnormalities include:
- dysmetria - clumsy movement w/overshooting the mark and occurs w/cerebellar disorders and alcohol intoxication
- past pointing: a constant deviation to one side
- intention tremor: where reaching to a visually directed object
- lack of coordination
What are some abnormal findings for a balance test?
- problems w/coordination
- stiff, immobile posture, staggering/reeling wide base for support/balance
- lack of arm swing/rigid arms
- unequal rhythm of steps, slapping of foot scraping of toe to shoe
- ataxia: uncoordinated or unsteady gait
- crooked line of walk
When might a positive rombergs test occur?
with cerebellar ataxia:
- MS
- alcohol intoxication
- loss of proprioception
- loss of vestibular function
What are some abnormal findings of the anterolateral tract?
- ** tongue blade test ***
- hypoalgesia: dec. pain sensation
- analgesia: absent pain sensation
- hyperalgesia: inc. pain sensation
- ** cotton ball test ***
- hypoesthesia: dec. touch sensation
- anesthesia: absent touch sensation
- hyperesthesia: inc. touch sensation
What are some abnormal findings for fine touch and sterognosis?
- problems w/tactile discrimination occur w/lesions of the sensory cortex or posterior column
- astereognosis: inability to identify objects correctly (occurs w/sensory cortex lesions)
What is clonus and when should you test for it?
repeated reflex muscular movements; tested when the reflexes are hyperactive
In what order is the neurological check conducted?
- LOC
- motor function
- pupillary response
- vital signs (pulse and BP are unreliable parameters of CNS deficit - cushing reflex shows signs of intracranial pressure)
Why was the glasgow coma scale created and what does it show?
as an accurate and reliable quantitative tool; standardized, objective and defines the LOC by giving it a numeric value. it assess for eye opening, verbal response and motor response. it also assess the functional state of the brain as a whole
** alert/normal person has a score of 15 whereas a score of < 7 reflects coma ***
What is dyskinesias?
repetitive stereotyped movements in the jaw lips or tongue that may accompany senile tremors
What are some sudden but common s/sx of a stroke?
- weakness/numbness in the face, arms, or legs
- confusion, trouble speaking or understanding
- changes in vision (blurry vision, partial or complete loss of vision)
- trouble with walking, dizziness, loss of balance or coordination
- severe HA w/no reason
*** FAST *** F = face drooping A = arm weakness S = speech difficulty T = time to call 911
What are the 10 warning signs of Alzheimers disease?
- memory loss - forgetting recently learned info. w/o being able to recall it
- losing track - cant perform familiar tasks
- forgetting words - forgetting simple words or substituting unusual words
- getting lost - disoriented to time/place
- poor judgment - inappropriately dressed, giving out excess money
- abstract failing - forgetting what numbers are for and how they are used
- losing things - putting things in unusual places
- mood swings - rapid change in mood/behavior for no reason
- personality change
- growing passive loss of initiative, sitting in front of chair all day or sleeping and not wanting to do activities
What are some abnormalities in muscle movement?
- paralysis - dec/loss of motor power caused by issue w/motor nerve or muscle fibers
> hemiplegia: spastic or flaccid paralysis on one side of body
> paraplegia: symmetric paralysis of both lower extremities
> quadriplegia: paralysis in all 4 extremities
> paresis - weakness of muscle rather than paralysis - TICS - involuntary and repetitive twitching of a muscle group
- myoclonus - rapid/short series of jerks at fairly regular intervals
> hiccup is a myoclonus of the diaphragm - fasciculation - rapid, continuous twitching of resting muscle w/o movement of limb
- chorea - sudden, rapid and jerky purposeless movements involving limbs, trunk or face (occurs at irregular intervals); disappears w/sleep
- athetosis - slow, twisting continuous movement resembling a snake or worm; involves distal limb more than proximal limb; occurs w/cerebral palsy and goes away w/sleep
