Neuroanatomy 3 Flashcards
where do sensory fibres that result from a motor response feed back to?
cerebellum
what are basal ganglia
series of grey matter structures key to the initiation and inhibition of movement (are technically nuclei)
where is the cerebellum located and what does it control?
posterior cranial fossa
movement
how many lobes does the cerebellum have and what are they called?
3 lobes
anterior, posterior, flocculonodular
largest lobe of the cerebellum?
posterior lobe
what lies immediately superior to the cerebellum?
tentorium cerebelli
the cerebellum is attached to the brainstem via _ stalks called….
3
penduncles
name the 3 different cerebellar peduncles
superior
inferior
middle (biggest)
what fissure divides the anterior and posterior lobes of the cerebellum?
primary fissure
what runs through the middle of the whole cerebellum?
superior vermis
name the 3 layers of the cerebellum from superficial to deep
molecular (synapses occur here)
purkinje cell
granule cell (most neurons here)
main afferents the cerebellum receives?
spinal cord via tracts
cerebral cortex
vestibular apparatus
how do afferents reach the cerebellum and convey their information?
enter via the peduncles and project to the granule cell layer
where do most of the cerebellum’s efferent axons synapse?
thalamus
what carries the only efferent output from the cerebellum
axons of purkinje cells
cerebellar hemispheres influence the ____ side of the body
ipsilateral
a midline lesion of the cerebellum will cause a problem with…
postural control
what will happen if 1 cerebellar hemisphere is disturbed?
coordination is slowed and can show an unsteady gait
bilateral cerebellar dysfunction will cause..
slow, slurred speech
ataxia
think DRUNK
functions of the basal ganglia
facilitate purposeful movement
inhibit unwanted movements
control posture and muscle tone
where are the basal ganglia located?
base of a cerebral hemisphere
which part of the basal ganglia appears as 2 stripes
globus pallidus
what structure of the basal ganglia runs around the lateral ventricle forming a “horn”
caudate nucleus
outer part of the lentiform nucleus is called the ___
putamen
what structure is medial to the lentiform nucleus
thalamus
how would you be able to identify the substantia nigra in the midbrain
look for 2 black lines
which condition causes loss of neurons of the substantia nigra
parkinsons
describe the direct pathway controlled by the basal ganglia
neurons in cerebral cortex activated
excitatory activity arrives at putamen
inhibitory neuron activated which makes the next neuron in the thalamus faster (too slow to reach it)
signal reaches the cortex again
how can inhibitory neurons actually speed up a signal?
if an inhibitory neuron is activated it projects its inhibitory signal very SLOWLY which means the next neuron is more likely to excite and work faster as it isnt being inhibited much
how do the basal ganglia suppress unwanted movement? via what pathway?
slows down excitatory neurons by inhibiting outflow of the thalamus which make the inhibitory neurons work better
via the INDIRECT PATHWAY
if someone struggles to initiate movement, what pathway is disturbed
direct pathway
damage to the cerebellum on 1 side will affect the contralateral side T or F
F! will always affect ipsilateral side unlike the rest of the brain
basal ganglion dysfunction will affect the contralateral side of the brain T or F
T, will always affect the other side
main effects of damage to basal ganglia
dyskinesias
change in muscle
NB DO NOT CAUSE PARALYSIS/ATAXIA
damage to basal ganglia affects sensory/motor function?
motor only
main pathology in huntingtons?
degeneration of basal ganglia and cerebral cortex
is parkinsons a problem of the basal ganglia?
yes as it affects the substantia nigra which are a component of the BG
