neuro exam 2 Flashcards
what is the passageway of information after an action potential in the peripheral axon
axon of afferent neuron > cell body in DRG > p. horn SC > ascending tract > thalamus > primary sensory cortex for interpretation
what does temporospatial summation mean
the stimulus was strong enough to generate an action potential in the peripheral axon
def superficial/cutaneous sensations
info from skin and subcutaneous tissue= touch, temperature, pain
discriminative touch
light, can sense superficial vibration and pressure, can determine the form, texture and shape of what is touching
crude/coarse touch
localized touch that includes tickle, itch, sexual sensation
temperature in somatosensory system includes
ability to sense relative temperature and changes to temperature
pain in somatosensory system perception
any noxious sensation ex) dull, local, burn, stab
fast pain vs slow pain
instant, sharp, localized vs dull, difused, not localized
3 examples of deep sensations of proprioception
joint position sense, kindesthesia, deep vibration (tuning fork)
cortical fine/light tough sensations includes
2 point discrimination, bilateral simultaneous stimulation, graphesthesia, localization of tough
why is cortical touch important
necessary to have fine touch to be able to interpret= cortical
2 point discrimination
the ability to discern whether 2 nearby objects touching the skin are truly 2 parts not one
how does 2 point discrimination differ from normal touch
finer sensation is required to be better at detecting the stimulus and interpreting the difference between 2 spots
bilateral simultaneous stimulation
ability to determine that two simultaneous stimulations are being applied to the opposite side of the body
if someone had poor/absent bilateral simultaneous stimulation where would the problem be in the brain
damage to cortex b/c that’s what interprets the sensations > won’t be able to feel the sensation bilaterally if this is the case
tactile extinction
inability to recognize two simultaneous stimuli on opposite sides of the body/proximally/distally even though the stimuli can be sensed alone
graphesthesia
ability to recognize writing on the skin by touch
localization of touch
knowing where the touch is felt and being able to identify it
if a patient has the sensation but can’t interpret it correctly where is the deficit
in the cortex on the opposite side of the brain
stereognosis
ability to recognize the form of objects by touch > needs light tough and conscious proprioception to achieve this
barognosis
ability to tell what an object’s relative weight is > uses touch and proprioception
receptive field
region of space where presence of stimulus will alter firing of the neuron
what’s an example of a small receptive field
fingers and toes > have greater density for finer tuned sensation
tonic receptors
respond as long as stimulus is sustained
phasic receptors
adapt to a constant stimulus and stop responding > brief adapation
phasic receptors include
mechanoreceptors, chemoreceptors, thermoreceptors, nocioceptors
mechanoreceptors
respond to mechanical deformation of receptor > touch, pressure, stretch, vibration
chemoreceptors
respond to chemical released by cells due to injury and pain, involved in pain and itch senses ex) allergic response or inflammation
thermoreceptors
sense relative body temperature and changes to temperature
nocioceptors
respond to stimuli that threaten or damage tissue (noxious)
what are nocioceptors experienced as
just pain, not the sensation
superficial dermis receptors examples
merkel’s discs, meissner’s corpuscles, hair follicle receptors
superficial dermis receptors function
respond to very local information, these receptors are very dense in the fingers
merkel’s discs respond to
pressure, fine touch, superficial vibration in the skin
meissner’s corpuscles respond to
skin deformation, light touch, vibration
hair follicle receptors respond to
hair displacement
deep dermis/subcutaneous fine touch receptors function
provide information about larger body surface areas > proprioception
deep dermis/subcutaneous fine touch receptors examples
ruffini endings, pacinian corpuscles
ruffini endings respond to
detect skin stretch and contribute to proprioception
pacinian corpuscles respond to
touch and deep vibration that contribute to proprioception
what physiologically gives coarse touch throughout the skin
free nerve endings
how is thermoreception felt
free nerve endings adapt to maintained temperatures
2 types of nocioceptors
specific and polymodal
specific nocioceptors respond to
one type of stimulus ex) high intensity mechanical, thermal, chemical
specific nocioceptors produce what kind of pain
localized pain, transmitted rapidly through myelinated fibers (fast pain)
polymodal nocioceptors respond to
not specific, will respond to any high intensity mechanical, chemical, thermal stimulus
polymodal nocioceptors transmit what kind of pain
poorly localized, unmyelinated C fibers, long-lasting pain
muscle spindle made up of
mechanoreceptors: intrafusal fibers that respond to stretch of a muscle
what are the 3 parts of a muscle spindle
intrafusal muscle fibers, sensory afferents Ia and IIa, gamma motor efferent fibers
what ____fusal fibers actually cause muscle contraction
extrafusal
what is the function of intrafusal fibers
only contract at the ends, defines 2 types: nuclear bag (clump arranged) and nuclear chain (single file arranged)
type 1a afferent neurons= annulospiral
wrap around central region of intrafusal fibers
what do type 1a afferent neurons do
respond to rapid stretch and send info to p. horn of SC
what do type 2a afferent neurons do
respond to rapid and sustained stretch, aka flower spray
gamma motor neurons
maintain sensitivity of spindle to allow for stretch, causes ends of INTRAFUSAL to contract even when muscle is on slack
alpha motor neuron
sends message to EXTRAFUSAL fibers to prevent overstretching, allows antagonist to relax
golgi tendon organs
at musculotendinous junction, provide info about muscle tension to inhibit response to excessive tension
when the muscle contracts what happens to the GTO
collagen fibrils pulled right which activates 1b afferent neurons
what is autogenic inhibition
GTO causes muscle to inhibit itself and interrupt contraction thus causing muscle to relax
what do joint receptors respond to
mechanical deformation of ligaments and capsules
examples of joint receptors
ligament receptors, ruffini endings, pacinian corpuscles, free nerve endings
what is proprioception helpful with
detecting size, shape, weight of an object, barognosis, sterognosis
where do somatosensory fibers derive from cells
dorsal root ganglion
what does alpha beta nerve fiber carry
info related to touch and conscious proprioception
what nerve fibers carry info for unconscious proprioception
1a (muscle spindle), 1b (GTO), II (flower spray)
what info do alpha delta nerve fibers carry
fast pain, cool temp, noxious heat
are alpha delta nerve fibers myelinated or nonmyelinated
myelinated
are c nerve fibers myelinated or nonmyelinated
nonmyelinated
what do c nerve fibers carry
slow pain, warm temp, itch
what damage to nerves cause glove and stocking distribution
peripheral neuropathy
examples of glove and stocking distribution
diabetic, chemotoxic, alcoholic: all lead to sensory deficit
where are cell bodies of spinal cord primary neurons located
outside SC in dorsal root ganglion
what matter is rexed lamina
grey matter
how is rex lamina divided
function and sensory info arrives at specific areas
rexed lamina 2 also known as
substantia gelatinosa: important for pain sensation
noxious stimuli sensed where
posterior dorsal horn
what nucleus is involved with unconscious proprioception
clarke’s nucleus: posterior sprinocerebellar tract
what are the ascending tracts of spinal cord
conscious pathways, fine/coarse touch and proprioception
what is the pathway of unconscious proprioception
spinocerebellar pathways to cerebellum
what sensations are part of medial leminscal pathway
conscious proprioception, vibration, discriminative touch
first order neuron of medial leminscus pathway
ipsilateral posterior columns to posterior column nuclei in the medulla
medial portion of medial lemniscus pathway
gracile fasiculus: info from LE and trunk to nucleus gracilis
lateral portion of medial lemniscal pathway
cuneatus fasiculus: info from upper trunk
what tract does immediate: fast and localized pain go through
lateral spinothalamic tract
what order neurons are in the lissauer tract of the lateral spinothalamic tract
first order
where do second order neurons cross the spinal cord
anterior white commissure and ascend in the lateral spinothalamic tract
what part of the brain is the first to process and send off info to the brain
thalamus
what system does slow pain pass through
medial pain system
where does the spinomesencephalic tract pass
midbrain to periaqueductal gray
where does spinoreticular tract pass
reticular formation
where does spinolimbic tract pass through
thalamic nuclei
what info does spinocerebellar system provide
unconscious proprioception and mvmt related to the cerebellum
does the posterior spinocerebellar and cuneocerebellar pathway have ipsilateral or contralateral transmission
ipsilateral
what nuclei innervate the posterior spinocerebellar pathway
clarks nucleus aka nucleus dorsalis
posterior spinocerebellar pathway info from where
legs and lower body
cuneocerebellar pathways gets infro from
arms and upper body
what do these injuries of the spinal cord cause: 1. transection, 2. hemicord lesion, 3. anterior cord lesion, 4. posterior cord lesion, 5. central cord lesion
1.sensory loss modalities bilaterally below level of injury
2.ipsilateral loss touch and proprioception
3. bilateral loss of pain and temperature
4. bilateral loss touch and proprioception
5. upper extremity issues
where does the first stage of sensory integration and perceptual awareness occur
thalamus
where do thalamocortical projections travel
to primary somesthetic area in parietal lobe to the primary somatosensory cortex then to the secondary somatosensory cortex
how is the primary somatosensory cortex (SI) organized
sensory homunculus
what is secondary somatosensory area SII involved with
shape and texture discrimination, bilateral activities, graphesthesia
what brocas areas are involved with somatosensory association area
areas 5 and 7
where do the SI and SII converge
posterior parietal cortex
what causes unilateral neglect
large lesions of non-dominant hemispheres that can feel but not recognize self or objects on left side
where is the highest number of sensory cells located in the humunculus
hands and mouth
what may damage to the anterolateral systems cause
sharp burning or searing pain
what can lesions to the thalamus lead to
severe contralateral pain
what can lesions of the cortex lead to
contralateral anesthesia, paresthesia or impaired sensory function
what would damage to the cortex cause
loss of 2 point discrimination, sterogenosis, graphesthesia
accurate for touch but unable to localize feeling
contralateral cortical damage
if someone is able to sense specific touch but unable to identify bilateral simulatenous touch what damage has occured
to the contralateral parietal lobe
if someone is unable to sense pain there is probably damage to
lateral spinothalamic tract or primary sensory cortex
why do we examine sensation
determine pattern, modality, level, severeity of impairment
what is stocking and glove pattern caused by
peripheral neuropathy
how should sensory testing proceed on the patient
from proximal to distal and general to specific
what type of touch is used to test the DCML
light touch
how should localization of touch be tested
either w/ pain or touch, we don’t have to test both for localization specifically
what temperature should warm + cold be tested at
40 deg C and 10 deg C
where should the tuning fork be placed for vibration on UE and LE
test head of 1st MC or ulnar styloid
test great toe or mallelous
where should two point separation be placed
2-4 mm on finger pads, 8-15 mm on palms, 3-4 cm shins
how is stereognosis tested
place one random common object in hand of patient and tell them not to look at it, do 3 times in one hand and 3 in the other hand to see if they can identify the object
if patient is unable to recognize objects with their hand without looking where is the damage
likely parietal lobe
where do reflexes happen
in the SC not periphery
necessary components for effective motor control
volition, coordination of muscle groups, proprioception, posture, sensory feedback, unconscious processing, adaptability
where is automatic movement and posture controlled at
brainstem
prefrontal cortex function
select appropriate actions for behavior
pre motor cortex function
select approprioate motor plans and processes complex sequences of tasks
posterior parietal cortex
movements that are targeted accurately in external space
primary motor cortex function
execute voluntary movement
brainstem function
conduit for descending motor tracts
motor control is facilitated by what
basal ganglia and cerebellum
where are motor control cell bodies found
layers 3&5 cortex and brainstem, usually 1st order neurons
where are lower motor neuron cell bodies
ventral spinal cord, include spinal and peripheral nerves
are cranial nerves upper or lower motor neurons
lower
which motor neurons directly control skeletal muscle
lower motor neurons
alpha motor neurons synapse where
extrafusal fibers
what do alpha motor neurons control
force production of skeletal muscle contraction
what do gamma motor neurons control
ongoing proprioceptive input of muscle spindles
gamma motor neurons synapse where
intrafusal fibers
what is alpha gamma co-activation
motor neurons provided with sensory input from muscle spindles and GTOs regarding length and tension of muscle
what ratio of motor neuron to muscle fiber do you need for more fine movements
lower ratio
what is an example of central pattern generators
walking= rhythmic behaviors the spinal cord is responsible for
motor neurons supplying limbs and axial muscles are found where in the somatotopic arrangement
medial
motor neurons that supply peripheral limbs tend to be found where somatotopically
lateral
what is pre synaptic inhibition useful for
preventing excessive reflex responses to normal changes in muscle length
what type of responses are monosynaptic
DTR and other reflexes
where do monosynaptic reflexes come from
muscle spindle
what does a myotatic reflex mean
involuntary
what is the scale for reflexes that is used when testing
0= no response
1=slight response, may or may not be normal for the pt
2= brisk response: normal
3= very brisk response= may or may not be normal for the pt
4=repeated reflex= always abnormal
what does reciprocal inhibition mean
inhibition of antagonist, contraction of agonist
what groups and muscle fibers are involved with reciprocal inhibition
group 1a, muscle spindle
what is an example of reciprocal inhibition
contract the quad to relax the hamstring, this method is especially helpful after surgery
autogenic inhibition means
inhibition of agnost followed by contraction of GTO to cause relaxation
withdrawal reflex circuit
withdrawal of harmful stimulus: motor neuron regulates its own activity by inhibiting itself when it fires
what does paralysis mean
complete injury of muscles due to spinal nerve or peripheral nerve damage
paresis means
weakness of muscles in spinal or peripheral nerve, incomplete damage
muscle atrophy means
rapid denervation of muscle, long term result of paralysis
fasciculations means
visible surface, quickly muscle twitches supplied by single motor unit
fibrilations means
twitches felt by patient but are not necessarily visible
hyporeflexia means
can’t complete stretch reflex arc
hypotonia means
abnormally low resistance to passive stretch of a muscle, felt in PROM
flaccidity means
no resistance to passive movement, floppy feeling
what lower motor neurons execute voluntary movement of the extremities
giant betz cells/pyramidal cells
primary cortex produces contralateral or ipsilateral movements
contralateral
functions of primary motor cortex
encodes force, direction, extent, speed of movement
purpose of association cortex
NOT motor areas > only ensure movements are appropriate for the person
what part of the brain is important for spatial relations
posterior parietal
direct cortical innervation includes what tracts
corticospinal and corticobulbar
indirect cortical innervation includes
corticorubral, corticoreticular
where does the corticoreticular tract originate
premotor cortex
what do lateral descending tracts control
proximal and distal muscles, voluntary movement of extremities
medial descending tracts control
axial muscles, posture, balance
what descending pathways control extensor anti-gravity tone
medial
what are the 3 lateral descending tract pathways
lateral corticospinal, corticobulbar, rubriospinal
what are the 3 medial descending pathway tracts
vestibulospinal, reticulospinal, medial corticospinal
what are the exceptions to the corticobulbar tract innervation
bilaterally except for lower facial nuclei and cranial nerve 12
what is the most important pathway for controlling voluntary mvmt
lateral corticospinal tract
what tract has axons that terminate directly on a motor neurons
lateral corticospinal
where do 15% of fibers of corticospinal tract descend IL and cross where
cross at segmental level of medial corticospinal tract
what does the brainstem act as for corticospianl tract via cerebral peduncles
conduit
where do axons from the cortex synapse
brainstem nuclei of second order neurons
what are tracts that originate in the medulla and project to the spinal cord
rubrospinal, reticulospinal, vestibulospinal
what do descending tracts originating in the BRAINSTEM contribute to
voluntary movement
when do rubrospinal tract cross
immediately to spinal neurons at ALL levels of SC to provide alternative path for voluntary motor commands
does the medial reticulospinal tract cross
it originates in motor neuron nuclei of reticular formation and DOES NOT cross, but will exit at ALL levels of SC
what is medial reticulospinal tract responsible for
locomotion and postural control
what is medial vestibulospinal tract responsible for
transmitting info from inner ear (CN8) to maintain balance and posture
is medial vestibulospinal tract bilateral or not
yes, splits immediately to become bilateral and exits at all levels ABOVE T6
why is it uncommon for there to be complete paralysis in the body
there’s lots of places motor control overlaps so even if one nerve is injured, there’s likely another nerve going to that same place within the CNS
4 Ds of brainstem dysfunction
dysphagia, diplopia, dysarthia, dysmetria
what is locked in syndrome
stroke at basilar artery denying blood to the pons so pt is awake but can’t move or communicate at all
what does bulbar mean
medulla
what dysfunctions may occur w/ bulbar damage
difficulty swallowing, speaking, chewing
how can a bulbar dysfunction occur
damage at corticobulbar tract or to LMN of cranial nerves
upper facial nucleus differentiates ______ and lower facial nucleus differentiates _______
bilaterally, contralaterally
damage to upper or lower facial nucleus has a greater risk for more cortical damage
lower
upper facial nucleus innervates _____ and lower facial nucleus innerves ______
above eys, below eyes
if the entire facial nerve is damaged at the nucleus what would be the most likely result
Bell’s palsy b/c IL paralysis of all facial muscles
if there’s damage in the cortex what will be the result
paralysis of CL side lower nucleus only (not upper nucleus b/c gets bilateral innervation so the other nerve will innervate that side)
what cortex are responsible for behavioral contex, emotions ,behavior
pre-frontal = frontal assiciation
rubrospinal tract begins _____ and has _____ transmission of info to the SC. it crosses ______ at _______
red nucleus, CL, immediately, all levels of SC
what does medial reticulospinal tract innervate
extensor muscles, axial muscles, postural support = locomation and postural control
what does dysarthria mean
slurred speech = brainstem dysfunction = medical emergency
what does dysmetria mean
impaired coordination w/ volume and direction of mvmt = brainstem damage
what movement can a patient with locked in syndrome still do
vertical eye mvmt and blinking
what part of the brain is responsible for us learning movements
cerebellum
what do AROM, PROM, RROM look for in a neurological exam
A: preliminary strength, motor control, pain
P: joint range, pain, tone
R: strength
what are you looking for with RROM in a neuro patient
myotome patterns, local to the muscle= peripheral nerve, entire side of the body= cortex
how should a neuro exam be completed
test one full arm, then the other, looking for strength deficit/weaknesses against gravity, then assess tone as needed
what would you expect a patient to have if there’s LMN damage
low tone or flaccid, could also be hyporeflexive or have muscle cramping
what is muscle tone resistance to
passive movement
what are 2 examples of LMN damage and a DECREASE in tone
hypotonia and flaccidity
what is an example of UMN damage and an INCREASE in tone
spasticity
what are examples of spasticity
caused by cerebral lesions, chronic, caused by SC lesion
spasticity caused by cerebral lesion description
caused by rapid build up of excitation w/ bias of involvement of antigravity muscles
spasticity caused by SC lesion description
slow increase in excitation, overactivity of flexors and extensors
chronic spasticity description
changes in rhelogic properties involved and neighboring muscles that leads to stiffness, contracture, atrophy, fibrosis
what is the normal appearance of spasticity
LE: extension, UE: flexion
does rigidity respond to changes in velocity of movement
no, it does not
what are some problems rigidity is associated w/
parkinsons
parkinsons is a dysfunction of what part of the brain
basal ganglia
what is decebrate posture
extension of arms AND legs, backward arch of head, usually caused by severe injury at brainstem
what is decorticate posture
flexed UE, extended LE, brainstem still functioning but lost cortical influence
is decorticate or decebrate more severe
decebrate
where is damage for decorticate and decerebrate injuries
-above level of midbrain
-below level of red nucleus, involves brainstem and cerebellum
def apraxia
inability to perform purposeful mvmt even though they do have the available mvmt due to damage of pre-motor and supplementary areas
what is most common cause of locked in syndrome
acute pontine lesion
compare ideamotor and ideational apraxia
can’t do mvmt with command but can do mvmt automatically; can’t do mvmt with command and can’t do mvmt automatically
bulbar palsy s/s
dysphonia (difficulty w/ volume of speech and speaking loud enough), tongue atrophy, articulation problems (due to facial nerve damage), dysphagia (difficulty swallowing)
what is sialhorea
drooling
s/s of pseudobulbar damage
sialhorea, paralyzed tongue, dysphonia, dysphagia
what does emotional liability mean
inappropriate emotional responses or exaggerated response, may include limb involvements
what is an abnormal response to babinki sign
extension of big toe, fanning of other toes
what is a normal response to babinski sign
flexion of big toe and usually flexion of other toes
what damage causes babinksi sign
descending UMN pathways
what is clonus
repetitive, rhythmic contraction of muscle when attempting to hold it in a stretched state, strong DTR when CNS doesn’t inhibit it
what causes the abnormal response to clonus test
quick and firm dorsiflexion leads to downward beating of foot
examples of disorders that may lead to UMN syndrome
cerebral palsy, multiple sclerosis, traumatic brain injury, stroke, spinal cord, neurodegenerative diseases
what does cerebral palsy look like
excessive effort with spasticity
what is the difference between a positive and negative sign
positive is something shows up when it’s not supposed to, negative is something is lost when it’s supposed to be there
examples of positive spasticity s/s UMN lesion
increased muscle tone, exaggerated DTR, iincreased stretch reflex, babisnki response, dyssenergic mvmt patterns
examples of positive s/s LMN lesion
paralysis, paresis, muscle atrophy, areflexia, muscle fibrilations
negative s/s UMN lesion
loss finger dexterity, weakness, fatigue, loss of fractionation (ability to selectively control muscles and limb segments), loss dexterity
are positive or negative signs more associated with loss of function
negative
3 stages of neuro embryology
pre= conception- day 14
embryotic= day 15-8 wks
fetal= 8th wk= birth
what stage does repeated cell division result in morula
pre-embryotic
when does a blastocyst of rapidly dividing cells usually form
day 5-6
when does a blastocyst implant to the uterine wall
pre-embryotic, after that the mesoderm begins to form
what stage of neuroembryology do major organs and systems differentiate
embryotic
what is the ectoderm made up of
sensory organs, epidermis, nervous system
what does the endoderm turn into
liver, gut, pancreas
when does gastrulation happen
week 3 of embrytoic phase, generates into 3 layers
when does myelination begin
fetal stage
neural plate, neural tube, neural groove, neural tube formation during fetal stage
-thick ectoderm in contact w/ amniotic fluid
-neuralplate turns to tubular structure where brain and spinal cord originate
-neural plate folds to form
-increase in folds, where the brain and SC develop
def anencephaly
incomplete/ no brain development
def spina bifida
protrusion of spinal cord
what happens on day 26
2 concentric rings are formed: mantel layer= inner, marginal layer= outer
3 parts of somites
anteromedial: forms vertebrae and skull
posteriomedial: forms skeletal muscle
lateral: forms skin from dermatomes
when does brain formation begin
day 28
3 parts of brain
hindbrain: rhombencephalon, later forms into pons, medulla, cerebellum
midbrain: mesencephalon: later forms into midbrain
forebrain: prosencephalon, later forms into P region that becomes diencephalon and A region that becomes telencephalon
when does myelination begin
4th month of fetus and completed in 3rd yearh
when do neurons differentiate
after reaching final location
