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The Motor Cortical Areas and Descending Pathways 

The Motor Cortical Areas and Descending Pathways
The Motor Cortical Areas and Descending Pathways

Per Brodal

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date: 01 March 2021

Chapter 22 deals with the control of complex, purposeful movements. The most direct control is exerted by upper motor neurons in the cerebral cortex, forming the pyramidal tract that is indispensable precise finger movements. The corticoreticulospinal pathways are important for fairly crude, stereotyped voluntary movements of the extremities. Rhythm generators in the spinal cord and the brain stem control locomotion and respiration. Supraspinal control of locomotion depends on a mesencephalic locomotor region (MLR). Motor cortical areas, notably the primary motor area (MI), the premotor area (PMA), and the supplementary motor area (SMA) are also discussed. The MI gives origin to a large part of the pyramidal tract fibers. The PMA and SMA act largely by “instructing” the MI what to do. The final part of the chapter deals with symptoms resulting from damage to the central motor pathways. Main characteristics of central pareses are hyperreflexia (spasticity) and loss of dexterity.

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