practical 3 motor pathways W3 Flashcards
frontal lobe - motor structures?
primary motor cortex (pre-central gyrus)
pre-motor cortex (anterior to primary motor cortex)
Broca’s area (motor control of speech)
which hemisphere is Broca’s area predominantly located?
dominant hemisphere (usually left)
which region of the primary motor cortex gives rise to the upper motor neurons concerned with cortico-bulbar projections?
inferior lateral
which region of the primary motor cortex gives rise to the upper motor neurons concerned with cortico-spinal projections?
superior medial
corona radiata?
contains projection fibres passing down from the cortical surface into the internal capsule
where in the internal capsule are the corticospinal and corticobulbar fibres located?
posterior limb of the internal capsule
corticospinal: near retrolenticular region
corticobulbar: nearer genu
corticospinal pathway?
->primary motor cortex
->corona radiata
->internal capsule
->crus cerebri
->pyramid
->decussation of the pyramid
->lateral corticospinal tract
->ventral horn
where are the cell bodies of the upper motor neurons in the corticospinal tract primarily located?
principally in the primary motor cortex
where are the cell bodies of lower motor neurons located?
in ventral grey horn of the spinal cord (axons exit spinal cord in ventral root and merge with dorsal root to form a mixed spinal nerve)
what happens to the majority of descending cortico-spinal motor axons at the decussation of the pyramids?
the cross to the contralateral side
location of crus cerebri?
large ventral/lateral structure in midbrain
location of pyramids of the medulla?
medial ventral columns in medulla.
how to identify decussation of the pyramids on an isolated brainstem?
area of pyramids where the ventral median fissure is obscured.
on a cross section, large area of crossing fibres between pyramids
approximate location of lateral and ventral corticospinal tracts in spinal cord cross sections?
lateral: lateral to dorsal horn
medial: along ventral median fissure
main difference between lateral and ventral corticospinal tracts?
lateral: decussated in medulla
ventral: ipsilateral, will decussate in spinal cord close to vertebral level where target lower motor neurons are located
do upper motor neurons in the lateral and ventral corticospinal tracts synapse on lower motor neurons in the ipsilateral or contralateral ventral grey horn of the spinal cord?
nearly all synapse on to lower motor neurons on the contralateral side
4 important extrapyramidal tracts?
rubrospinal
vestibulospinal
tectospinal
reticulospinal
where are the UMN cell bodies of the rubrospinal tract located?
red nucleus
where are the UMN cell bodies of the vestibulospinal tract located?
vestibular nuclei
where are the UMN cell bodies of the tectospinal tract located?
superior colliculus
where are the UMN cell bodies of the reticulospinal tract located?
reticular formation
location of the red nucleus?
midbrain
bilateral oval structures deep to substantia nigra and crus cerebri
location of the superior colliculus?
midbrain
bilateral oval structures on dorsal side. superior to inferior colliculus. below thalamus.
location of the vestibular nuclei?
pons
dorsal
where does the vestibulospinal tract receive information from? what does it activate?
receives info from labyrinthine system and cerebellum
activates extensor motor neurons concerned with maintenance of anti-gravity posture
where does the rubrospinal tract receive information from? what does it activate?
receives info from cortex and cerebellum
activates motor neurons of flexor muscles
where does the reticulospinal tract receive information from? what does it activate?
receives information from the hypothalamus
activates motor neurons concerned with reflex activity, muscle tone, breathing and circulatory system
where does the tectospinal tract receive information from? what does it activate?
receives information from visual system
activates motor neurons reflex response to visual stimuli
features of the basal ganglia?
sub-cortical nuclei
extensive connections to cortex and thalamus
‘checking system’ for motor activity
facilitate wanted movements
eliminate inappropriate movements
major components of the basal ganglia?
caudate nucleus
putamen
globus pallidus
substantial nigra
what do the caudate nucleus and putamen form?
neostriatum (striatum)
location of the caudate nucleus?
follows curvature of lateral ventricle.
on a horizontal section, the head is found anterior and medial to the anterior limb of the internal capsule
on a coronal section, found between the internal capsule and the corpus callosum
location of the putamen?
on a horizontal section, found lateral to globus pallidus
location of the globus pallidus?
on a horizontal section, lateral to the internal capsule (internal and external segments)
location of the substantia nigra?
ventral midbrain
deep to the crus cerebri
principle functional pathways through the basal ganglia?
the direct pathway: promotes movement
the indirect pathway: inhibits movement
what neurotransmitter does the substantia nigra use? what is its effect?
dopamine
activates striatum (direct pathway)
inhibits striatum (indirect pathway)
have you learnt the diagram yet!! (in notion notes - basal ganglia pathways)
!!!
