Basal Ganglia, Cerebellum, & CN Motor Pathways Flashcards
what are the parts of the basal ganglia?
striatum, lenticular nucleus, substantia nigra, subthalamic nucleus
what makes up the striatum?
putamen, nucleus accumbens, caudate nucleus
this is a functional nucleus
what makes up the lenticular nucleus?
putamen and globus pallidus
what is the net affect of the direct pathway?
turn on the motor cortex
disinhibition of thalamic control of motor planning
what is the net affect of the indirect pathway?
turning off the motor cortex
activation of inhibition
draw the direct pathway
draw the indirect pathway
draw the indirect dopamine pathway
what is Parkinson’s? what are some characteristics of Parkinson’s?
a hypo kinetic disorder caused by depletion of dopamine particularly in the substantial nigra
resting tremors, shuffling gait, cogwheel rigidity
what is hemiballismus?
a hyperkinetic disorder in which the subthalamic nucleus is affected
violent, involuntary movement of proximal limbs
what is Huntington’s disease?
hyperkinetic disorder in which the striatum is primarily affected
dancing movement of distal limbs
what are the three functional divisions of the cerebellum?
spinocerebellum, cerebrocerebellum, vestibulocerebellum
spinocerebellum
made up of the vermis and paravermis
postural and movement control of trunk and limbs
cerebrocerebellum
lateral hemispheres
fine motor and non-motor planning
vestibulocerebellum
flocculonodular lobe
coordinating head and eye movements
what are the deep nuclei of the cerebellum?
dentate, emboliform, globose, fastigial
what is the dentate nucleus?
relay nucleus of the cerebrocerebellum to motor centers
what are the emboliform and globose nucleus?
aka interposed nuclei
relay nuclei of the spino-cerebellum to motor centers
what does the fastigial nucleus do?
project to reticular formation and vestibular nuclei
what are the afferent tracts of the inferior cerebellar peduncle?
olivocerebellar, dorsal spinocerebellar, cuneocerebellar, vestibulocerebellar
what are the efferent tracts of the inferior cerebellar peduncle?
vestibulospinal tract
fibers from the fastigial nucleus travel to join with CN VIII
what are the afferent tracts of the middle cerebellar peduncle?
pontocerebellar
what are the afferent tracts of the superior cerebellar peduncle?
ventral and rostral spinocerebellar
what are the efferent tracts of the superior cerebellar peduncle?
dentatothalamic tract
fibers from the interposed nuclei
why are ventral and rostral spinocerebellar tracts special?
they provide anatomical insurance since they are functionally very similar to the dorsocerebellar and cuneocerebellar tracts
what are the input tracts of the spinocerebellum?
Dorsal and ventral spinocerebellar (LE&T)
cuneocerebellar and rostral spinocerebellar (UE)
what is special about the rostral and ventral spinocerebellar tracts?
they double cross, go to the contralateral side and then back to the ipsilateral side
what is the pathway of the dorsal spinocerebellar tract?
starts by following the gracile fascicle in the dorsal columns, which then ascends and synapses on Clark’s nucleus in the thoracic sc area
the tract will move more dorsolateral in the sc and ascend through the inferior cerebellar peduncle
what is the pathway of the cuneocerebellar tract?
follows the cuneate fascicle and synapses on the cuneate nucleus in the medulla
ascends through the inferior cerebellar peduncle
where does the fastigial nucleus project to?
the reticular formation in the reticulospinal tract and vestibular nuclei in the vestibulospinal tract
spinocerebellum output
where does the interposed nuclei project to?
the red nucleus and ventrolateral nucleus of the thalamus
where does the vestibulocerebellum get input from?
directly from vestibular afferents, vestibular nuclei
what are the outputs of the vestibulocerebellum?
medial longitudinal fasciculus
medial vestibulospinal - coordinates neck/eye movements
lateral vestibulospinal - maintains balance
what are the inputs of the cerebrocerebellum?
corticopontine fibers - pontine nuclei - pontocerebellar tract projects to the contralateral cerebellum
cortico-rubro-olivary pathway leads to the olivocerebellar tract
what are the outputs of the cerebrocerebellum?
dentatothalamic fibers send signals to the ventrolateral nucleus of the thalamus
fibers to red nucleus form loop through inferior olivary nucleus
what are the layers of the cerebellum from outside to inside?
molecular layer, purkinje cell, granular cell layer
what do granular cells receive input from?
all pathways but the inferior olive
what do purkinje cells receive input from?
contralateral inferior olive (climbing fibers) and granule cells
where do purkinje cells project to?
deep nuclei
symptoms of vestibulocerebellum lesion
wide gait, nystagmus
symptoms of spinocerebellum lesion
ataxia, stomping gait
symptoms of cerebrocerebellum lesion
intention tremor, dysdiadochokinesia
fine motor loss
where are the oculomotor and Edinger-Westphal nuclei located?
what is the blood supply?
rostral midbrain at the level of the red nucleus
paramedian branches from basilar or PCA
where is the trochlear nucleus located? what is the blood supply?
dorsal, caudal midbrain
nerve fibers decussate immediately in the tectum
paramedian branches or PCA
where is the trigeminal motor nucleus located? what is the blood supply?
medial to principle sensory nucleus mid -pons
AICA or circumferential branches
where is the abducens nucleus located? what is the blood supply?
the dorsal aspect of the caudal pons
paramedian branches
where is the facial nucleus located? what is the blood supply?
ventral area of the tegmentum in the caudal pons
AICA or circumferential branches
where is the superior salivatory nucleus located?
dorsomedial to the facial nucleus in mid to caudal pons
where is the nucleus ambiguus located? what is the blood supply?
mid to central portion of the rostral medulla
PICA
where is the dorsal motor nucleus of vagus located? what is the blood supply?
in rostral medulla, deep to vagal trigone
provides parasymp innervation for most visceral organs in thorax/abdomen
PICA
where is the spinal accessory nucleus located? what is the blood supply?
in the same area as the ventral horn in the upper cervical sc
PICA or VA
where is the hypoglossal nucleus located? what is the blood supply?
in rostral medulla deep to hypoglossal trigone
ASA or VA
