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Resources for Communication Problems
Thursday, March 13, 2008
Chapter 14Motor System 4 : Motor Cortex
The several motor cortices control voluntary manipulative and delicate motor movements and initiate motor performance.Descending cortical projections to the motor neurons travel via two pathways, the corticobulbar tract and the corticospinal tract, collectively called the pyramidal tract. These tracts control cranial and spinal motor neurons (LMN), respectively. Activity at the motor cortex is influenced by extensive feedback channels from the cerebellum, brainstem, thalamus, and basal ganglia.
A lesion interrupting the excitatory projections from the motor cortex results in a specific loss of delicate motor control.It also results in sings of muscle weakness, flaccid tone, hyporeflexia, and loss of reflexes.However, in several weeks, the hyporeflexia and flaccid tone are replaced by increased reflexes (hyperreflexia ) and spastic tone in muscles.