neuroscience exam 2 Flashcards
what is the job of the basal ganglia?
initiation of mvmt
what is the job of the cerebellum?
coordination of ONGOING mvmt
where do UMNs deliver signal to?
brainstem and spinal cord
where do LMNs transmit signals to?
directly to skeletal muscles
where is the cell body of a LMN?
in the ventral horn
what is a motor unit?
an alpha motor neuron and the muscle fibers it innervates
where does the alpha motor neuron project to?
project to extrafusal muscle
releases ACh to contract them
where does the gamma motor neuron project to?
intrafusal fibers in the muscle spindle
responsible for proprioception
what do extrafusal muscle fibers do?
generate force
describe intrafusal muscle fibers
too small to generate significant force
very very actin/myosin
innervated by sensory and motor
helps detect muscle stretch
how are cell bodies of LMNs organized?
extensors - anterior
flexors - posterior
distal muscles - lateral
proximal muscles - medial
what are some signs of lower motor syndrome?
paresis/paralysis
hypotonia/flaccidity
decreased/loss of reflexes
atrophy - more severe than UMN
involuntary muscle contraction
define fasciciulations
quick twitches
entire motor unit
visible on skin
not always pathologic
if last for days-weeks can be pathologic
define fibrillations
brief contractions
single muscle fiber
not visible to eye
always pathologic
what does the medial corticospinal tract do?
controls neck, shoulder, and trunk muscles
what does the reticulospinal tract do?
control bilateral postural muscles, antigravity and gross limb mvmts
what does the lateral vestibulospinal tract do?
control postural muscles
maintain COG over BOS in upright position
what does the medial vestibulospinal tract do?
control neck and upper neck muscles
what does the lateral corticospinal tract do?
controls selective motor control, fine distal mvmts
isolating one joint
is affected most in stroke/TBI
dr. rawal’s most important - will most likely have ?’s on test
what does the rubrospinal tract do?
control extension of wrist and fingers
what does the lat CS tract pass through between the cortex and the midbrain?
internal capsule
if there is a lesion at T12 in the right side, which impairments will the person have?
DCML: ipsi (crosses above lesion)
ST: contra (crosses after lesion)
lat CS: ipsi (crosses above lesion)
med CS: no effect (does not reach T12)
where do fibers project to in the corticobrainstem tracts?
CN nuclei in the brainstem
are CB injuries ipsi or contra?
isolated CN - ipsi
brainstem injury - contra
what are the 5 steps between a decision and the skeletal muscle?
neural activity begins with decision in anterior frontal lobe
motor planning areas active, followed by control circuits
control circuits, consisting of cerebellum and basal ganglia, regulate activity in UMN tracts
UMN tracts deliver signals to spinal interneurons and LMNS
LMNs transmit signals directly to skeletal muscles, eliciting a contraction
what are examples of UMN syndromes?
tumor
stroke
MS
TBI
CP
ALS
SCI
what are examples of LMN syndromes?
ALS
polio
CN injury
bells palsy - CN7
nerve lesion
peripheral neuropathy
10 common impairments in UMN lesions
abnormal synergy - mus cannot coordinate
abnormal co-contraction
hyperreflexia
muscle contracture - tightens mus
hypertonia
muscle overactivity
muscle tone - high or low cause weaker mus
myoplasticity
paresis
spasticity
what are peripheral nerve?
any nerve distal to spinal nerves
what deficits does a lesion in a spinal nerve show?
myotomal/dermatomal distribution
what deficits does a lesion in a peripheral nerve show?
peripheral nerve distribution
what does the cervical plexus innervate?
cutan info from post scalp to clavicle
anterior neck muscles
diaphragm
what does the brachial plexus innervate?
entire UE
what does the lumbar plexus innervate?
skin and muscles of ant and medial thigh
what does the sacral plexus innervate?
post thigh and most of leg and foot
what are 4 signs of peripheral nerve damage?
sensory changes
autonomic changes
motor changes
denervation: trophic changes (pain and temp)
what kind of injuries cause mononeuropathy?
trauma
traumatic myelinopathy
traumatic axonopathy
traumatic severance
lundborg classification
physiological conduction block, myelin damage
axonal damage
axon + endo damage
axon + endo + peri damage
axon + endo + peri + epi damage
sunderland classification
I
II
III
IV
V
seddon classification
neurapraxia (transient block)
axonotmesis (lesion in continuity)
neurotmesis (division of a nerve) (stage 3-5 of sunder)
what is traumatic myelinopathy?
loss of myelin limited to site of injury
interferes with function of large diameter axons
focal compression is a cause
prognosis of myelinopathy
good in cases of focal compression
schwann can remyelinate
traumatic axonopathy
disrupts axons
affects all size axons
leaves mye intact
results in muscle atrophy, reduced reflexes, loss of sensation
can axons repair?
yes, if support structures are intact
regrowth: 1-2mm/day, 1 inch/month
what is axonal sprouting?
intact axons take over
changes in motor unit morphology
what happens during traumatic severance?
nerves are physically divided
complete interruption
describe repair of severance
requires surgical intervention
prognosis poor
muscle remains viable 12-18 months after denerv
what is multiple neuropathy?
2+ parts of the body
individual nerves are affected
random, asymmetrical presentation
diabetes or vascularitis
what is polyneuropathy?
involving multiple nerves
symmetrical, progressing distal to proximal
stocking and glove pattern
NOT result of trauma
LMN
what are the causes of polyneuro?
toxic
metabolic
autoimmune
therapeutic drugs
what is distal symmetrical polyneuro?
length-dependent
distally affected first
not isolated to a pattern
large fiber: sensory ataxia, proprio, vibration loss
small fiber: pain, temp, autonomic dysfuction
what are 3 types of acquired polyneuros?
diabetic
alcoholic
drug induced (chemo)
what is diabetic polyneuro?
nerve damage not reversible
90% of DM pts present with it
worse at night
what is charcot foot?
interaction of multiple factors within DM polyneuro
midfoot collapse with rockerbottom foot
orthotics necessary
medical management of DM polyneuro
improve glycemic control
pain treatment challenging
meds: anticonvulsants, antidepressants, opioids
PT for DM polyneuro
foot care
education
address balance/gait impairments
exercise
describe alcoholic polyneuro
is it due to alcohol or vitamin def
nutrition usually poor
may be reversible
need to abstain from alcohol
what is chemotherapy induced polyneuro?
neurotoxic effects of many cancer agents
very similar to DM polyneuro
what is genetic polyneuro?
most common is charcot-marie-tooth:
slow prog
many subtypes
dom or recessive
slowly progressive
symptoms of charcot marie tooth
high arch
foot drop
slapping gait
loss of muscle in lower legs
numbness in feet
difficulty with balance
later, appear in arms and hands
what is guillain-barre syndrome?
polyneuro
paresis may be worse proximally
onset is rapid
treatment required to prevent respiratory failure
recovery of function proceeds proximal to distal
diagnosis of polyneuro
eval guides treatment
look for patterns
nerve biopsy
genetic testing
electrodiagnostic studies
electrical activity from nerve conduction and EMG studies
nerve conduction studies
application of external current and record response from large diameter; myelinated axons
key parameters: latency, velocity, amplitude
electromyography
insertion of recording electrode into muscle
key parameters: insertional and rest activity, recruitment activity
general guidelines to diagnosing myelin
nerve study latency
nerve conduction velocity
slow nerve conduction
general guidelines to diagnosing axons
nerve study amplitude - decrease
electromyography
clinical testing
2/3 signs high evidence of peri neuro
absence of ankle jerk
impaired vibration
impaired position sense of great toe
treatment of polyneuro
results of sensory, MMT, electrodiagnostic guide
education to prevent complications from damage
sensory considerations of treatment
visually inspect areas
proper foot care
balance effects
nightlights for bathroom trips at night
motor considerations of treatment
strengthen to prognosis and goals
consider whether pt is reconditioned
orthoses used to stabilize WB joints
what is paresis and paralysis?
paresis: partial loss of voluntary contraction
paralysis: complete loss of voluntary contraction
happens in both UMN and LMN
when corticospinal tracts are interrupted, which tract helps retain some movement of the upper arm?
reticulospinal
what types of muscle atrophy do we see at UMN and LMN?
UMN: disuse from lack of muscle use
LMN: denervation of skeletal muscle - most severe
what is impaired selective control?
interruption of lateral corticospinal tract
specific muscles cannot be activated independently
what is spasticity?
hypertonia from UMN
abnormally strong resistance to passive stretch
velocity dependent
limits joint ROM
what is rigidity?
velocity independent
increase in resistance to stretch
seen in parkinson’s (neither UMN or LMN)
what is hypotonia?
seen in LMN
abnormally low resistance to passive stretch
what is flaccidity?
lack of resistance to passive stretch
complete loss of muscle tone
seen initially in UMN and in LMN
what happens to muscle tone when someone has a stroke?
when in initial shock, they will have hypotonia or flaccidity
once they start recovering, it will switch to hypertonia
what is the clasp-knife response?
when a muscle is slowly passively stretched and resistance drops at a specific point in ROM
what is a medication for spasticity?
botulinum toxin - prevents lower motor neurons from releasing ACh
what are the components of a normal reflex?
sensory receptor
afferent neurons
integration
efferent neuron
effector organ
describe the stretch reflex
whenever a muscle is stretched, excitation of spindle causes reflex contraction of muscle
what are the most common abnormal reflexes?
hyperreflexia
clonus
babinski sign
hyporeflexia
what is hyperreflexia?
loss of inhibitory corticospinal input combined with enhanced excitability of LMN response
excessive firing of LMN
postive - prevents muscle atrophy
describe clonus
involuntary, repeating, rhythmic
sustained clonus is always pathological
lack of UMN control
count to 10 and documents 10+ beats
describe babinski sign
extension of great toe, accompanied by fanning of other toes
stroke lateral sole of foot from heel to ball of foot
what is myoplasticity?
adaptive structural changes within a muscle in response to changes in NM activity
describe ALS
affects both UMN and LMN
onset between 40 and 70
20% more common in men
90% without family history
excessive glutamate
sensory will be normal
what is guillain barre syndrome?
acute inflam and demy of peripheral fibers
good prognosis, eventually recover but may have some degree of weakness
2-3 weeks after mild infection
may need hospital for respiratory help
what are common infections that kickstart GBS?
campylobacteriosis
mycoplasma
pneumoniae
epstein barr
varicella-zoster
zika
what is the onset pattern of GBS
rapid onset, plateau then gradual recovery
symmetrical motor loss distal to proximal
recover proximal to distal
which CN does GBS affect?
7, 9,10
treatment for GBS
plasmapheresis
intravenous immunoglobulin therapy
PT and OT rec
avoid overworking muscles
facilitate resolution of respiratory problems
orthotics
tips to take care of feet
check everyday
wash everyday
smooth corns and calluses gently
trim your toenails straight across
wear shoes and socks always
protect your feet from hot and cold
keep blood flowing to feet
get foot check every dr visit
which cranial nerves have autonomic functions?
3, 7, 9, 10
what is the path of transmission of the olfactory nerve?
nasal receptors
olfactory bulbs
olfactory cortex in the insula
how often do olfactory cells undergo replacement?
30-90 days
what parts of the limbic system receive olfactory input?
amygdala - emotional response
hypothalamus - odor affects hunger
hippocampus - judgement and decisions involving smell
summary of olfactory nerve
special sensory
afferents for olfaction
how does the optic nerve work?
light strikes the retina and is converted into neural signals by photosensitive cells
info is carried by optic nerve
what part of the thalamus is involved in vision?
lateral geniculate
summary of optic nerve
special sensory
vision
afferents for pupillary and accommodation reflexes
what is accommodation?
how good your lens acommodates near/far vision
how would you test the optic nerve?
vision charts
what are the 3 motor nerves of the eye?
oculomotor
trochlear
abducens
what are the 6 extraocular muscles and their innervation?
lateral rectus - abd - 6
medial rectus - add - 3
inferior rectus - down - 3
superior rectus - up - 3
inferior oblique - extorsion (ER) - 3
superior oblique - intorsion (IR) - 6
what are the other muscles of CN 3?
levator palpebrae superioris - lifts eyelid
pupillary sphincter muscles/iris muscles
ciliary muscles - changes shape of lens
what is synergistic action related to eye muscles?
coordination between the two eyes
what controls head and eye coordination?
MLF
the eyes will follow the head
what CN does the MLF include?
3, 4, 6, 8, 11
what are the parasym functions of CN 3?
constriction of the pupil
pupillary reflex: constriction of the pupil in the eye directly stimulates by bright light
consensual reflex: constriction of pupil in the other eye
accommodation reflex: contraction of muscles controlling the lens of eye
summary of oculomotor nerve
motor:
moves eye up, down, medial, elevates eye lid
parasym:
consensual and accommodation reflexes
summary of trochlear nerve
motor
moves eye medially and down (superior oblique)
summary of abducens nerve
motor
abducts eye (lateral rectus)
what is the masseter reflex?
masseter is tapped with reflex hammer, muscle contracts
what is corneal reflex?
when cornea is touched, eyes close
what is the swallowing reflex?
food touching entrance of pharynx elicits mvmt of soft palate and contraction of pharyngeal muscles
