BRAIN control of Movement Flashcards
lower motor neuron lesion
what would happen if you damaged 1 lower motor neurone in the body
only the muscles that are innvervated by those nerves those are damaged
descending spinal tracts
what are the lateral descending spinal tracts and what are their function?
- corticospinal tract
- rubrospinal tract
responsible for fine/discrete motor control (i.e picking up a small object)
descending spinal tracts
what are the 4 ventromedial descending spinal tracts?
- tectospinal tract
- vestibulospinal tract
- pontine reticulospinal tract
- medullary reticulospinal tract
lateral pathways: corticospinal/pyramidal tract
where does the corticospinal tract originate, where does it cross over and where does it collect
- originates in motor cortex
- decussates at pyramids
- collects in lateral column of spinal cord
corticospinal tract
what side of the body does the corticospinal tract control?
controls the contralateral side (opposite side to where it originates)
lateral pathways
what are the other 2 branches of the corticospinal tract, what percentage of the tract do they make up and where do they cross over
anterior corticospinal tract:
- 8 percent
- does not cross over at pyramids, instead crosses over where it is going to synapse
uncrossed lateral corticospinal tract:
- 2 percent
- does not cross over at all
concscious motor command
explain how conscious motor command from the cortex to the periphery through the central nervous system works for the corticospinal tract
- first order motor nerve fibres (upper motor neurones) of corticospinal tract run through midbrain and decussate at the medulla, where they then descend down the lateral white matter of the spinal cord
- when it reaches the periphery, the upper motor nerve synapses with the alpha, second order motor nerve fibres (lower motor neurones) in the anterior (ventral) horn of the grey matter of the spinal cord.
- the second order motor nerve fibres exit spinal cord in the ventral spinal root
- the anterior (ventral) and posterior (Dorsal) roots join to form the spinal nerve which exits the vertebral column through the intervertebral foramen
other lateral pathways
where does the rubrospinal tract originate from and what is the source of input for this origin
- originates from red nucleus in brainstem
- motor cortex is source of input
ventromedial pathways
what does the vestibulospinal tract control, where does it originate and what is its function
- controls posture of head and neck
- originates in vestibular nuclei
- relays information from vestibular labyrith of inner ear
ventromedial pathways
where does the tectospinal tract originate, what type of information does its origin receive and what is its function
- originates in Superior colliculus/optic tectum
- optic tectum receives visual, auditory and sensory input
- function is orienting responses
ventromedial pathways
what does the Pontine (medial) reticulospinal tract enhance and help maintain
- enhances antigravity reflexes of spinal cord
- helps maintain a standing position
ventromedial pathways
what does the medullary (lateral) reticulospinal tract do and what does it help maintain??
- liberates antigravity muscles from reflex control (i.e dampens down spinal reflex to optimize muscle tone)
- helps maintain standing position
ventromedial pathways
what is activity in both reticulospinal tracts tracts controlled by?
- controlled by descending signals from motor cortex
lateral descending motor pathways
what do the corticospinal and rubrospinal pathways together make?
- lateral column
brainstem descending motor pathways
what do the tectospinal, vestibulospinal and reticulospinal motor pathways make up and where do they terminate?
- they make up the ventromedial column
- terminate in ventromedial spinal grey matter
brainstem descending motor pathways
where does the rubrospinal tract terminate?
terminates in the ventrolateral spinal grey matter
descending motor pathways
what are upper motor neurones/first order neurones in the cortex that communicate with neurones in the brainstem called?
corticobulbar tracts
descending motor pathways
what are neurones that originate in the brainstem and communicate with neurones in the spinal cord called
bulbospinal tracts
locked in syndrome
what is locked-in syndrome and what does it cause
- lesion basilar pons
significant loss of function in corticobulbar and corticospinal tracts, so:
- paralysis of most motor functions like limbs and motor cranial nerves
locked in syndrome
what is the only things retained in locked in syndrome
- blinking
- vertical gaze
motor cortex
what is to the left of the central sulcus
primary motor cortex
what 2 places does the supplementary motor area receive input from and what is its role
- cerebellum
- basal ganglia
role in coordinating voluntary movement
what 3 places does the primary motor cortex receive information from?
From:
- primary somatosensory crotex
- supplementary motor area
- premotor cortex
what does the promotr cortex play a role in
role in movements that need visual guidance
what does the primary somatosensory cortex do for the primary motor cortex
- delivers proprioceptie and tactile inputs to primary motor cortex
what do patients with SMA lesions display?
apraxia
what is apraxia
inability to initiate specific purposeful movements
what does the posterior parietal cortex play role in
role in movements that need visual guidances
waht do patients with PPC lesions display?
display:
- apraxia
- sensory neglect
cortiocospinal tract lesions
what 2 things does injury to a lower motor neuron in the cortiocospinal tract lead to and what side of the body will the effects be seen?
- muscle weakness/total paralysis of muscles supplied by this nerve
- reduced/absent muscle tone (hypotonia)
- ## These symptoms will be seen on the SAME side of the body
what 4 things can happens if there is a lesion in the upper motor neurones and where will these symptoms be seen?
- muscle weakness/total paralysis of muscles
- increased muscle tone (hypertonia)
- spasticity
- abnormal reflexes like Babinski reflex
- These symptoms will be seen on the OPPOSITE side of the body
