1/2: Neuroscience Review - O'Connell

Question 1

Define lower motor neuron lesion; descibe symptoms

Answer 1

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.

Question 2

Define upper motor neuron lesion; descibe symptoms

Answer 2

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.

Question 3

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. ?

Answer 3

right anterior cerebral a. correlates with left genitalia, thigh and feet. Middle cerebral a. correlates with fingers, face, arm (everything else)

Question 4

Match sensory fiber size/type with function

Answer 4

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.

Question 5

which fiber is responsible for fast pain? For propioception?

Answer 5

fast pain = group III/Adelta

large sensory fibers (group I/II responsible for propioception (and fine tactile sensations, two point discrimination and vibratory sensation.)

Question 6

Describe the role of enkephalin interneurons in nociceptive sensory tranmission. Which areas of the nervous system excite the enkephalin interneurons?

Answer 6

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”

Question 7

fasciculation

Answer 7

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

Question 8

fibrillation

Answer 8

a small, local, involuntary, muscular contraction, due to spontaneous activation of single muscle cells or muscle fibers.

Question 9

motor neuron pool

Answer 9

all motor neurons innervating a muscle

Question 10

motor unit

Answer 10

a motor neuron and all the muscle fibers it innervates

Question 11

paraplegia v. quadriplegia

Answer 11

transection of spinal cord below cervical level but above lumbar enalrgement
high cervical level lesion

Question 12

ataxia; cerebellar ataxia; sensory ataxia

Answer 12

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

Question 13

intention tremor v. resting tremor

Answer 13

resting associated with Parkinsons

intention associated with Cerebellar issues

Question 14

lead pipe rigidity and cogwheel rigidity

Answer 14

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

Question 15

bradykinesia

Answer 15

slowness in execution of movement

Question 16

akinesia

Answer 16

lack of movement

Question 17

dysdiadochokinesia

Answer 17

inability to perform rapid alternating movements -

Question 18

dysmetria and hypermetria

Answer 18

errors in range and force of movements

voluntary muscular movement over reaches the intended goal

Question 19

chorea

Answer 19

involuntary movment; brief sudden random twitch “dance like”

Question 20

dystonia

Answer 20

neurological movement disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal posture

Question 21

atheotosis

Answer 21

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.

Question 22

describe the lesion responsible for parkinsons and give characteristic signs of disease

Answer 22

Degeneration of dopaminergic projection to striatum from substantia nigra

Observe: tremor at rest, rigidity, slowing of movement and postural instability.

Question 23

describe lesion responsible for huntigton’s disease and give characteristic signs of disease

Answer 23

Selective loss of GABA/enkephalin projection from striatum to globus pallidus
Later more sidespread degeneration of striatal neurons.

Observe: chorea, dementia, bradykinesia.

Question 24

damage to r. dorsal column =

Answer 24

loss of propioception, discriminative touch and vibratory sense in right foot

Question 25

damage to somatosensory area of r. thalamus would cause?

Answer 25

loss of dorsal colum mediated sensation in l. foot

Question 26

damage to posterior limb of internal capsule OR to the somatosensory cortex?

Answer 26

contralateral deficits in dorsal column mediated sensations

Question 27

stereognosis and grphestesia are lost ___ to a lesion of the somatosensory cortex, thalamus, or medial lemniscus

Answer 27

contralateral - these higher functions are lost ipsilateral to a dorsal column lesion

Question 28

nociceptive information from the viscer is carried in..

Answer 28

dorsal columns

Question 29

system responsible for carrying nociceptive and thermoceptive signals from Ad and C fibers

Answer 29

anterolateral system - also includes information from mechanoreceptors with large receptor fields (crude touch)

Question 30

midline lesion of the spinal cord (ex: early syringomyelia) cause?. To pain and temp sensation

Answer 30

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

Question 31

brown-sequard syndrome **

Answer 31

hemisection of spinal cord = loss of dorsal column sensations ipsilateral to lesion and pain and thermal sensation contralateral to the lesion

Question 32

a brainstem lesion above the medulla causes?

Answer 32

deficits of all somatosensory modalities contralateral to the lesion; posterior internal capsule and cerebal cortex lesion also cause contralateral deficits

Question 33

describe parietal neglect syndrome

Answer 33

usually result of lesion to non-dominant hemisphere; since language usually in l. hemisphere, lesion of right hemisphere can cause left-sided neglect

Question 34

presynaptic problem with NMJ might be? postsynaptic might be?

Answer 34

botulism
myasthenia gravis (autoimmune with antibodies against nicotinic Ach receptors)

Question 35

lesions of large areas of motor cortex can cause?.

Answer 35

upper motor neuron lesion symptoms contralateral to the lesion

Question 36

lesions of the spinal cord can cause?

Answer 36

upper motor neuron symptoms for ipsilateral muscles innervated by neurons below the level of the lesion

Question 37

effects of lesions in the vestibulocerebellum

Answer 37

distrubances of equilibrium and eye movemet control (smooth pursuit), ataxic gait

Question 38

effects of lesion in the spinocerebellum

Answer 38

IPSIALTERAL problems in control of leg movmeents persist when pt is supine

Question 39

symptoms are ___ to cerebellar lesions

Answer 39

ipsilateral

Question 40

only problems raising one corner of mouth vs. problems with eye and mouth.

Answer 40

upper motor neuron defect : contralateral defect in lower face. . Lower motor neuron lesion: ipsilateral defects.

Question 41

effect of lesion of corticospinal tract

Answer 41

lose fine control of digits. Cannot perform individual movements of the digits

Question 42

brain stem lesion?

Answer 42

LMN cranial n. signs on side of lesion, UMN signs are seen on contralateral body

Question 43

ataxic gait falls?

Answer 43

toward side of cerebellar lesion

Question 44

causes intention tremor

Answer 44

dysmetria

Question 45

principle signs of cerebellum dysfunction

Answer 45

ataxic gait
nystagmus
dysmetria (intention tremor)
 dysdiadochokineasia
decomposition of movement