block 5 lecture 12 testing the muscles Flashcards
what are the three main types of movement?
reflex, rhymthmic, voluntary
what are the divisions of the motor system?
pyramidal and extrapyramidal
where do the upper motor neurons arise?
in the primary motor cortex
what do the upper motor neurons descend in?
the spinal cord
where do most upper motor neurons decussate?
medulla
what does the decussation of the upper motor neurons in the medulla give rise to?
lateral corticospinal tract
what is the tract called of those upper motor neurons that dont decussate in the m edulla?
ipsilateral corticospinal tract
where do the upper motor neurons synapse in the spinal cord?
spinal level of relevant spinal nerve with anterior horn cells
what are the inputs for movement to be coordinated?
premotor cortex, cerebellum/brain stem and directly by spinal reflexes
what is the extra-pyramidal system for?
balance, coordination, fine movement
what are the pyramidal tracts through?
cortocospinal tracts
what would you observe with upper motor neuron lesions?
muscle weakness, increased muscle tone, exaggerated reflex, clasp knife response, babinski sign
what would you expect to see with lower motor neuron lesions?
muscle weakness, reduced muscle tone, absent reflexes, muscle atrophy, muscle fasiculation
what do you get with extrapyramidal lesions?
dystonia, akisthisia, parkinsonism, dyskinesia
what is dystonia?
spasms
what is akisthisia?
motor restlessness`
dyskinesia?
jerky movements
what do you get with cerebellar lesions?
ipsilateral loss of coordination, past-pointing, disdiadochokinesia, ataxic gait, nystagmus,, dysarthria
disdiadochokinesia
ability to change direction quickly
nystagmus
rapid eye movements
dysarthria
muscles of speech affected
examples of upper motor neuron lesions?
stroke,MS,traumatic brain injury, cerebral palsy
examples of lower motor neuron lesions?
bells palsy, gillian bare syndrome, motor neurone diseases
what happens in brown sequard syndrome?
half the spinal cord is damaged
what are the consequences of brown sequard syndrome?
loss of ipsilateral fine touch and proprioception
loss of controlateral pain and temperature
what is anterior cord syndrom caused by?
damage to circulation
what are the consequences of anterior cord syndrome?
loss of pain and temperature
what happens to fine touch and proprioception in anterior cord syndrome?
preserved fine touch and proprioception
what happens in central cord syndrome?
variable sensory loss, motor deficits more in upper limbs
what are myofibril gathered into?
muscle fibers
wheredo motor neurons synapse with muscle?
neuromuscular junction
what happens when the neurotransmitters released?
the sarcolemma propagates an action potantial
what does the action potential generated in the sarcolemma travel down?
T tubules
what does the action potential traveling down the T tubules cause?
causes the sarcoplasmic reticulum to release calcium
what does calcium cause?
acts on myofibrils allowing muscle to shorten
what happens when calcium exposes the binding site between the actin and myosin?
the filaments slide over one another
when is energy needed during muscle contraction?
to break bonds
where does the sarcoplasmic reticulum release the calcium ions to during muscle contraction?
cytosol
what do the calcium ions bind to once in the cytosol?
troponin on the actin filaments
how is the myosin binding site exposed on the actin molecule
tropomyosin moves once calcium binds
what happens when the actin myosin binding site is exposed?
myosin cross bridges bind to the actin and strokes forward pulling actin
why do you get rigor mortis?
there is no energy to relax muscle
what happens in isometric muscle contraction?
muscle stays at a constant length
what are the different types of muscle contraction?
isometric, isotoinic and isokinetic
what is isotonic muscle contraction
contraction against natural resistance
what is isokinetic muscle contrction?
sports training
what is concentric muscle contraction?
muscle shortens
what is eccentric muscle contraction?
muscles may lengthen when contracting
