motor systems 2 Flashcards
which lobe is involved in motor control?
all of the frontal lobe
parietal lobe
what is the relationship between the position on the cortical region and the complexity of movement?
the more anterior the cortical region, the more complex role in movement
what is area 4?
primary motor cortex
where is the primary motor cortex?
immediately anterior to the central sulcus
what do lesions of the primary motor cortex cause?
cause initial paralysis or paresis of specific muscle groups
why is some recovery of function possible after lesions of the primary motor cortex?
bc of cortical plasticity
why is there a smaller chance of recovery with bigger lesions?
more muscle groups are involved
what part of the brain do strokes with MCA occlusion affect? what effect does this have and why?
- affects almost all of one side of the frontal lobe
- leads to severe motor disability in the contralateral body (apart from lower limb bc lower limb is supplied by the anterior cerebral artery)
what does an MI of the proximal MCA affect the blood supply to?
o Basal ganglia via lenticulostriate arteries
o Motor cortex
what is area 6?
premotor cortex
what is area 8?
supplementary motor cortex
what does damage to area 6 or 8 cause?
motor apraxia
how does motor apraxia present?
o Normal reflexes + no muscle weakness
o Difficulty performing complex motor tasks e.g. tying shoelace
why does damage to one side of the brain cause minimal symptoms?
bc the contralateral area can take over some functions of the damaged tissue
what are areas 7 and 19?
posterior parietal cortex
what does damage to areas 7 and 19 cause?
sensory apraxia
what is sensory apraxia?
Difficulty performing complex motor tasks when triggered by sensory input (e.g. when asked verbally to do something)
where are the FEFs and Broca’s area?
adjacent to the premotor area
what do the FEFs do?
motor control of extraocular eye muscles - controls voluntary eye movements
what is the function of Broca’s area?
muscles regulating speech
what does damage to Broca’s area cause?
motor aphasia
what is motor aphasia?
patient struggles w motor programmes to construct meaningful word sequences
what is oculomotor apraxia?
difficulty moving eyes horizontally + quickly
- Either have to turn head to follow object or use peripheral vision
what causes oculomotor apraxia?
bilateral lesions of the FEFs
what causes sensory apraxia?
caused by damage to connections from posterior parietal lobe to premotor cortex
what are areas 1, 2 and 3?
somatosensory cortex
where do 40% of corticobulbospinal tract axons come from? what do the axons do?
somatosensory cortex
Axons send instruction to spinal cord that modulate sensory input – modulate spinal reflexes (e.g. suppress nociceptive reflexes)
what are areas 9 and 10?
dorsolateral prefrontal cortex
what are the functions of areas 9 and 10?
Areas 9 & 10 – executive functions;
o Plan movement
o Evaluate possible future actions and decide which is best
o Involved in problem solving, judgement
what do lesions of the dorsolateral prefrontal cortex cause?
apathy, personality changes and lack of ability to plan or to sequence actions/tasks
what difference does it make if the dorsolateral prefrontal cortex lesion affects the left lobe vs the right lobe?
o Left hemisphere mainly affected – poor memory for verbal info
o Right hemisphere mainly affected – poor memory for spatial info
what is the wisconsin card sorting test?
common test for frontal lobe function - tests perseverence
what can cause frontal cortex damage?
impact w frontal bone e.g. road traffic accident or blow to the head that causes contusions
what are contusions?
brain bruising
what is area 11?
orbitofrontal cortex