1/2: Neuroscience Review - O'Connell Flashcards
Define lower motor neuron lesion; descibe symptoms
lower motor neuron = alpha motor neuron; located in anterior horn of spinal cord and cranial n. nuclei; innervate skeletal muscle fibers.
Symptoms = weak or paralyzed muscles. Decreased or absent muscle stretch reflexes. Flaccid weakness. Profound atrophy, fasciculations, fibrillations.
Define upper motor neuron lesion; descibe symptoms
immediate = spinal shock induced hypotonia and flaccid paralysis.
With time = spastic paralysis. Increased muscle stretch reflexes. Clonus. Babinski/extensor plantar resposne. Larger areas of body.
pt has an ischemic stroke involving the RIGHT ANTERIOR cerebral artery - what part of the body is affected? What if left? What if right/ left mddle cerebral a. ?
right anterior cerebral a. correlates with left genitalia, thigh and feet. Middle cerebral a. correlates with fingers, face, arm (everything else)
Match sensory fiber size/type with function
Ia = afferent muscle spindle
Ib = golgi tendon organ afferent
group I = Aalpha
Group II = Abeta
Group II = axons of encapsulated endings
Group III = Adelta
Group III = responsible for sharp fast pain
Group IV = C fibers.
Group C = burning slow pain.
which fiber is responsible for fast pain? For propioception?
fast pain = group III/Adelta
large sensory fibers (group I/II responsible for propioception (and fine tactile sensations, two point discrimination and vibratory sensation.)
Describe the role of enkephalin interneurons in nociceptive sensory tranmission. Which areas of the nervous system excite the enkephalin interneurons?
release from interneurons of enkephalins that inhibit the flow of pain information to the brain.
enkephalins (and dynorphin) are found in the periaqueductal gray, the medulla and the dorsal horns
“natural opiod”
fasciculation
a brief, spontaneous contraction affecting a small number of muscle fibers, often causing a flicker of movement under the skin.
It can be a symptom of disease of the motor neurons
fibrillation
a small, local, involuntary, muscular contraction, due to spontaneous activation of single muscle cells or muscle fibers.
motor neuron pool
all motor neurons innervating a muscle
motor unit
a motor neuron and all the muscle fibers it innervates
paraplegia v. quadriplegia
transection of spinal cord below cervical level but above lumbar enalrgement
high cervical level lesion
ataxia; cerebellar ataxia; sensory ataxia
failure of muscular coordination, defective muscular control resulting in irregular and jerky movements
ataxia due to lesion in the cerebellum itself
ataxia due to damage to the sensory input to the cerebellum
intention tremor v. resting tremor
resting associated with Parkinsons
intention associated with Cerebellar issues
lead pipe rigidity and cogwheel rigidity
Leadpipe rigidity results when an increase in muscle tone causes a sustained resistance to passive movement throughout the whole range of motion, with no fluctuations.
Cogwheel rigidity is a combination of lead-pipe rigidity and tremor which presents as a jerky resistance to passive movement as muscles tense and relax
bradykinesia
slowness in execution of movement
akinesia
lack of movement
dysdiadochokinesia
inability to perform rapid alternating movements -
dysmetria and hypermetria
errors in range and force of movements
voluntary muscular movement over reaches the intended goal
chorea
involuntary movment; brief sudden random twitch “dance like”
dystonia
neurological movement disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal posture
atheotosis
a condition in which abnormal muscle contractions cause involuntary writhing movements
It affects some people with cerebral palsy, impairing speech and use of the hands.
describe the lesion responsible for parkinsons and give characteristic signs of disease
Degeneration of dopaminergic projection to striatum from substantia nigra
Observe: tremor at rest, rigidity, slowing of movement and postural instability.
describe lesion responsible for huntigton’s disease and give characteristic signs of disease
Selective loss of GABA/enkephalin projection from striatum to globus pallidus
Later more sidespread degeneration of striatal neurons.
Observe: chorea, dementia, bradykinesia.
damage to r. dorsal column =
loss of propioception, discriminative touch and vibratory sense in right foot
damage to somatosensory area of r. thalamus would cause?
loss of dorsal colum mediated sensation in l. foot
damage to posterior limb of internal capsule OR to the somatosensory cortex?
contralateral deficits in dorsal column mediated sensations
stereognosis and grphestesia are lost ___ to a lesion of the somatosensory cortex, thalamus, or medial lemniscus
contralateral - these higher functions are lost ipsilateral to a dorsal column lesion
nociceptive information from the viscer is carried in..
dorsal columns
system responsible for carrying nociceptive and thermoceptive signals from Ad and C fibers
anterolateral system - also includes information from mechanoreceptors with large receptor fields (crude touch)
midline lesion of the spinal cord (ex: early syringomyelia) cause?. To pain and temp sensation
bilateral loss of pain and temperature at the level of the lesion
spinal cord lesions of just one side of the cord cause contralateral loss of pain and temp sensation
brown-sequard syndrome **
hemisection of spinal cord = loss of dorsal column sensations ipsilateral to lesion and pain and thermal sensation contralateral to the lesion
a brainstem lesion above the medulla causes?
deficits of all somatosensory modalities contralateral to the lesion; posterior internal capsule and cerebal cortex lesion also cause contralateral deficits
describe parietal neglect syndrome
usually result of lesion to non-dominant hemisphere; since language usually in l. hemisphere, lesion of right hemisphere can cause left-sided neglect
presynaptic problem with NMJ might be? postsynaptic might be?
botulism myasthenia gravis (autoimmune with antibodies against nicotinic Ach receptors)
lesions of large areas of motor cortex can cause?.
upper motor neuron lesion symptoms contralateral to the lesion
lesions of the spinal cord can cause?
upper motor neuron symptoms for ipsilateral muscles innervated by neurons below the level of the lesion
effects of lesions in the vestibulocerebellum
distrubances of equilibrium and eye movemet control (smooth pursuit), ataxic gait
effects of lesion in the spinocerebellum
IPSIALTERAL problems in control of leg movmeents persist when pt is supine
symptoms are ___ to cerebellar lesions
ipsilateral
only problems raising one corner of mouth vs. problems with eye and mouth.
upper motor neuron defect : contralateral defect in lower face. . Lower motor neuron lesion: ipsilateral defects.
effect of lesion of corticospinal tract
lose fine control of digits. Cannot perform individual movements of the digits
brain stem lesion?
LMN cranial n. signs on side of lesion, UMN signs are seen on contralateral body
ataxic gait falls?
toward side of cerebellar lesion
causes intention tremor
dysmetria
principle signs of cerebellum dysfunction
ataxic gait nystagmus dysmetria (intention tremor) dysdiadochokineasia decomposition of movement
