Norden - Extrapyramidal Motor System Flashcards
Involved in motor “programs” (arm swing when you walk), habitual behaviors, and in the modulation of movement
Extrapyramidal system
Involved in balance, equilibrium, posture, tone; the proper timing and coordination of learned, skilled motor movement and the correction of movement errors during on-going movement
Cerebellum
Neither the _ nor the _ project to the spinal cord, rather they have connections which influence firing of UMN’s in the corticospinal tract
Extrapyramidal system
Cerebellum
The major output division of the globus pallidus
GPi (glous pallidus internal portion)
Central players of the extrapyramidal system
Caudate and putamen
Hypo-kinetic disorders of the extrapyramidal motor system
Parkinson’s disease
Parkinsonism
Hyper-kinetic disorders of the extrapyramidal motor system
Huntington’s Chorea
Ballismus
Dystonia
• A family of disorders involving an abnormal posturing of the trunk or
extremity, caused by a sustained contraction and hypertrophy of muscles
involved
• Can be generalized or focal; most common focal are torticollis and
blepharospasm
• Etiology unknown; lentiform nucleus abnormalities have been found
• Can be primary (idiopathic) or secondary (called symptomatic)
Dystonia
Hyperkinetic extrapyramidal disorder • Due to lesions of the subthalamic nucleus • Results in violent, uncontrollable movements (contralateral to lesion) • Can be a fatal disorder
Ballismus
• ETIOLOGY: Autosomal dominant disorder with genetic anticipation linked
to an abnormal expansion in the length of a CAG triplet repeat sequence;
chromosome 4; hyperkinetic extrapyramidal disorder
• PATHOLOGY: A neurodegenerative disorder characterized by loss of the
medium-spiny neurons that are involved in the indirect pathway; overall
effect is to decrease inhibition of the thalamus (VA, VL) and thus
abnormally excite UMNs in cortex – leading to abnormal, uncontrollable
motor movements
• Also involves loss of other cortical neurons (prefontal cortex,
hippocampus)
• Results in chorea, mental changes
Huntington’s Chorea
this is the system that plans and initiates a voluntary motor movement (direct corticospinal) and maintains background tone in muscle that allows the movement to be made (indirect corticospinal
Pyramidal motor system
Plays a primary role in the execution of motor “programs”, habitual learning, and in the modulation of movement
Extrapyramidal motor system
Monitoring of on-going movement, proper timing and coordination of learned, skilled motor movement and the correction of movement errors during on-going movement
Cerebellum
Medium spiny neurons are prominent where ?
Neostriatum (caudate and putamen)
Medium spiny neurons are prominent in the neostriatum (caudate and putamen) and use ____ as a neurotransmitter
GABA
What are the excitatory neurons of the neostriatum ?
Aspiny neurons, excitatory, use acetylcholine
The pars compacta’s melanin containing neurons provide ______ input to the neostriatum
Domapinergic
The extrapyramidal motor system consists of ?
The neostriatum
Globus pallidus
Subthalamic nucleus
Substantia nigra
The 3 major afferent projections to the neostriatum are?
Cerebral cortex (cortico-striate)
Thalamus (thalamo-striate)
Substantia nigra (nigro-striate)
What Is the major neurotransmitter in cortico-striate and thalamo-striate projections?
Glutamate
Where do many of the cortico-striate axons come from?
A lot of them are collaterals from the cortico - spinal tract .
(This allows for the extrapyramidal system to “know” what movement is expected to be made)
What type of neurotransmitter does the pars compacta send to the striatum?
Dopamine.
Either + or -
What determines whether the dopamine that is used in the nigro-striate pathway is inhibitory or excitatory?
The type of postsynaptic dopamine receptor involved.
What are the major efferents out of the neostriatum ?
Globus pallidus and substantia nigra?
