25/26 Flashcards
collection of subcortical nuclei that function together to modify the output of the cerebral cortex; involved in motor initiation, planning, & control
BASAL GANGLIA
Componenets of what?
◦ caudate nucleus
◦ putamen
◦ nucleus accumbens
◦ globus pallidus
subthalamic nucleus
substantia nigra (
BASAL GANGLIA
globus pallidus + putamen =
LENTICULAR/Lentiform Nucleus
= caudate nucleus + putamen + nucleus accumbens
STRIATUM
what is the main input nuclei of the basal ganglia
STRIATUM
caudate nucleus + putamen + nucleus accumbens
the output nuclei for basal ganglia includes:
GLOBUS PALLIDUS
Substantia Nigra
the basal ganglia projects to what lobe
FRONTAL LOBE
most directly involved in planning and initiating movements
the SUBSTANTIA NIGRA is divided into 2 parts:
Pars Compacta
Pars Reticularis
part of substantia nigra
pigmented cells that produce dopamine; degenerate in Parkinson’s
PARS COMPACTA
part of substantia nigra
acts like a displaced piece of the globus pallidus, receives input from the striatum & projects to the thalamus
Pars Reticularis
the overall effect of the basal ganglia is to do what to the activity in the thalamus?
which in turn changes the activity and output of the cerebral cortex
INHIBIT activity in the thalamus
does the basal ganglia have direct outputs to LMNs
NO
can only influence muscle contraction INDIRECTLY through cerebral cortex and pyramidal system of UMNs
since most of descending corticospinal fibers of the pyramidal system decussate, dysfunction of the basal ganglia on one side results in abnormal motor activity on which side of the body?
CONTRALATERAL
Hallmark of basal ganglia disorder =
appearance of abnormal involuntary movements = DYSKINESIAS
DYSKINESIAS
dancelike movements
CHOREA
dyskinesias
recurrent, sinuous, writhing, or worm like movements
ATHETOSIS
dyskinesias
involuntary sustained muscle contractions that lead to abnormal positions and postures
DYSTONIA
Task specific - writers cramp
Blepharospasm - constant blinking
torticol
is there WEAKNESS associated with basal ganglia damage
NO bc LMN and UMN are not directly affected
ETIOLOGY
Degeneration in the Substantia nigra pars compacta
PARKINSONS – no longer activate direct pathway
Hallmark Symptoms of PARKINSONS
TRAP
TREMOR
RIGIDITY
AKINESIA or bradykinesa
Postural Instability
The first motor sign of PARKINSONS appear when pigmented dopamingergic neurons degenerate in what?
Pars Compacta of the Substantia Nigra
The degenerating neurons accumulate what in PARKINSONS?
Lewy Bodies
synthetic heroin containing MPTP can cause
MPTP induced parkinsonism
MPTP –> MPP in astocytes = towic breakdown product
Repetitive head trauma can cause what type of parkinsons
PUGLISITIC
