01/14 Motor Systems Flashcards
(23 cards)
Where are the upper motor neurons of the pyramidal system located?
In the precentral gyrus of the frontal lobe (Brodmann area 4)
What happens to 80-90% of the corticospinal tract axons in the distal medulla?
They cross to the opposite side at the pyramidal decussation
Where are the neurons which control movements of the face and mouth located?
Near the Sylvian/lateral fissure
Where are the neurons which control muscles of the thighs and legs located?
Near the medial longitudinal fissure and within the central sulcus
What are the components of the extrapyramidal motor system?
Substantia nigra Basal ganglia (caudate, putamen, globus pallidus) Subthalamic nucleus Red nucleus Thalamus
What are the general functions of the extrapyramidal motor system?
Dampens erratic motions
Maintains muscle tone and truncal stability
Degeneration of the substantia nigra leads to what neurological disorder?
Parkinson’s disease
What region of the brain is especially affected in Huntington’s chorea?
Caudate nucleus of the basal ganglia
Where are the vestibular nuclei located?
In the medulla, in the floor of the fourth ventricle
What are the four tracts of the cerebellum? What structures do they connect?
Spinocerebellar tract - spinal cord and cerebellum
Vestibulospinal tract - vestibular system and cerebellum
Corticopontocerebellar tract - cortex, pons, and cerebellum
Dentatorubrothalamic tract - dentate nucleus, red nucleus, and thalamus
What are the three major tracts of the vestibular system, and what are their functions?
Lateral vestibulospinal tract - maintains equilibrium
Vestibuloocular tract - controls saccadic eye movements
Vestibulocortical tract - causes dizziness when stimulated
Where are neurons of the sympathetic nervous system located?
Levels T1-L3 in the lateral gray spinal cord
What is the major neurotransmitter of the sympathetic nervous system?
Noradrenaline
Where are neurons of the parasympathetic nervous system located?
In the brainstem and sacral spinal cord
What is the major neurotransmitter of the parasympathetic nervous system?
Acetylcholine
What is the pyramidal/corticospinal motor system?
Two neuron system with upper motor neurons in the primary motor cortex and lower motor neurons in the anterior horn of the spinal cord
Controls all voluntary muscles movements
Trace the path of the neurons of the pyramidal motor system on their way to the LIMBS, from motor cortex to muscles
1) Motor strip (precentral gyrus, Brodmann area 4)
2) Internal capsule
3) Lateral corticospinal tract in the lateral cerebral peduncle
4) Pyramidal tract in the medulla
5) Synapse in anterior horn of the spinal cord
6) Exit the spinal cord via the ventral root
7) Limb muscles
Trace the path of the neurons of the pyramidal motor system on their way to the FACE, from motor cortex to muscles
1) Motor strip (precentral gyrus, Brodmann area 4)
2) Internal capsule
3) Corticobulbar tract in the medial cerebral peduncle
4) Synapse with lower motor neurons in cranial nerve nuclei (midbrain, pons, and medulla)
5) Facial muscles
What is hemiballismus? What can cause it?
A rare movement disorder characterized by flailing, ballistic movements of the limbs
Can be caused by lesions in the subthalamic nucleus
What is dentatorubral-pallidoluysian atrophy?
A genetic disorder characterized by ataxia, irregular twitching and twisting motions, and dementia
Exhibits degeneration of the red nucleus, the globus pallidus, the subthalamic nucleus, and the dentate nucleus of the cerebellum
What are the three main sensory components of the vestibular system in the inner ear?
Utricle
Saccule
Semicircular canals
Trace the path of the neurons of the vestibular system that maintain equilibrium, from the hair cells to the cerebellum
1) Hair cells in the semicircular canal
2) Vestibular ganglion in the bone of the skull
3) Superior and lateral vestibular nuclei in the medulla
4) Inferior cerebellar peduncle
5) Flocculonodular lobe of the cerebellum
What are the lobes of the cerebellum, and what are their major functions?
Flocculonodular lobe (archicerebellum) - maintains equilibrium Anterior lobe (paleocerebellum) - maintains muscle tone Posterior lateral lobes (neocerebellum) - controls coordination and intricate motor tasks, and plays a role in memory of fine motor skills
