Motor System Flashcards
where are the cell bodies of upper motor neurones found
in the motor cortex of the pre-central gyrus
what are the 2 functions of the UMNs
- directly excite LMN
- indirectly inhibit LMNs through interneurones
what is the net effect of UMN - is it excitatory or inhibitory on the LMNs
inhibitory
what is the corona radiata
bundles of radiating fibres making up the white tissue through which the axons of the UMNs travel through
at which point do the fibres making the corona radiata get much closer
internal capsule
what is the internal capsule
the space between the thalamus and the lentiform nucleus
describe the pathway of the UMNs which synapse with spinal nerves
descend through the corona radiata, through the internal capsule, cerebral puduncle, non, medullary pyramids and then descends and synapses at the ventral horn
where the the UMN decussate
at the medially pyramids
what is the name of the tract which UMN descend through to synapse with spinal nerves
coritcospinal tract
which side of the face do the UMNs suppling the upper face project
contraleterally and ipsilaterally
which side of the face do the UMNs suppling the lower face project
contralaterally only
what is the name of the tract for the UMNs involved with the facial nerve
corticobulbar tract
what are the signs of damage to the UMNs
weakness
hyperreflexia
hypertonia
extensor plantar reflex
what is spinal shock
this is where immediately after UMN damage the LMNs shut down so you get signs of LMN damage. however the LMNs gradually begin to work again so thats when you develop signs of a UMN damage
what are the signs of LMN damage
weakness areflexia hypotonia muscle wastage fasciculation
why is muscle wastage seen in a LMN lesion
as the LMNs supply trophic factors such as growth factors to their target muscles
what are the functions of LMNs
muscle contraction
spinal reflexes
where is the cell body of a LMN found
either in the ventral horn or motor-nuclei in the brainstem
what do the 3 cerebellar peduncles attach to
superior attaches to the midbrain
middle attaches to pons
inferior attaches to the medulla
does cerebellar damage cause contralateral or ipsilateral symptoms
ipsilateral
what are the causes of cerebellar damage
tumour, alcohol, stroke, MS, epilepsy medication
how can cerebellar injury cause hydrocephalus
lesions of the vermis can extend to compress the 4th ventricle
what are the symptoms of cerebellum damage
dysdiadochokinesis ataxia nystagmus intention tremor slurred speech hypotonia
what is the basal ganglia
a group of structures in the brain which help to coordinate and control motor function
what makes up the lentiform nucleus
putamen, globus pallidus externa and interna
what makes up the striatum
putamen and cordate nucleus
what makes up the substania nigra
pars compacta and pars recticularis
where in the basal ganglia are dopamingeric neurones found
pars compacta of the substania nigra
what does the direct pathway of the basal ganglia do
allows for movement due to stimulation of the motor cortex
what happens to the direct pathway of the basal ganglia in the presence of dopamine
there is increased stimulation of the motor cortex
what does the indirect pathway of the basal ganglia do
inhibits the stimulation of the motor cortex preventing movement
what happens to the indirect pathway of the basal ganglia in the presence of dopamine
it will then promote the stimulation of the motor cortex to allow for movement
what is motor neurone disease
a degenerative disorder affecting both upper and lower motor neurones
what are the causes of motor neurone disease
most are sporadic but can also be familial
what is Huntington’s disease
a progressive neurodegenerative disorder where there is cell loss in the striatum of the basal ganglia
which pathway of the basal ganglia is affected in Huntington’s disease
indirect - however, as the disease progresses it can also affect the direct pathway
what are the symptoms of huntingtons disease
chorea, dystonia, incoordination and cognitive decline
what is hemiballismus
where there is damage to the subthalamic nucleus resulting in abnormal unilateral movement
which pathway of the basal ganglia is affected in hemiballismus
indirect
what usually causes hemiballismus
sub-cortical stroke
what is parkinsons disease
where there is progressive degeneration of the substania nigra resulting is a dopamine deficiency
what are the features of parkinsons disease
resting tremor bradykinesia hypertonia shuffling gait dementia
