Unlock document.
This document is partially blurred.
Unlock all pages and 1 million more documents.
Get Access
CHAPTER 2
Chapter Overview
The parts of the nervous system that control voluntary movement are collectively referred
to as the “motor system.” The motor system is a complex system whereby thought is
turned into movement. When functioning properly, numerous muscles are able to move
in a coordinated manner, but when the motor system is damaged, the result may be a
debilitating movement disorder. The type of disorder depends on the location and extent
of damage to the motor system. In order to be an effective diagnostician, it is important to
understand how this system works.
The nervous system is divided into the central nervous system (CNS) and the peripheral
nervous system (PNS). The CNS consists of the brain and spinal cord, while the PNS
consists of the spinal and cranial nerves. The brain is divided into the cerebrum,
brainstem, and cerebellum. The cerebrum is divided into four lobes. Neurons are the
most important cells of the nervous system, as they are the means by which neural
impulses are transmitted from one part of the nervous system to another.
The desire to move is the starting place for any voluntary movement. Taking the desire
and turning it into movement is extremely complex. The primary cortices analyze sensory
information. The association cortex, which plays an important role in the initial planning
of voluntary movements, makes sense of the information from the primary cortex. The
association cortex then sends its neural signals of an intended movement to both the
basal ganglia and the cerebellum, which link the association cortex with the primary
motor cortex. That is, they take rough motor impulses from the association cortex,
smooth them out, coordinate them, and send them up to the primary motor cortex via the
thalamus. The cerebellum is believed to take the preliminary motor impulses from the
association cortex and integrate them with the sensory information available to it,
adjusting and refining the motor impulses before sending the processed motor signals to
the primary motor cortex via the thalamus. The thalamus, therefore, receives neural
inputs of planned motor movements from both the basal ganglia and the cerebellum.
Motor Speech Disorders, Second Edition
ii
7. How is it known that movements do not originate in the primary motor cortex?
8. What is the difference between the pyramidal and extrapyramidal tracts?
9. Describe the anatomical distinction between lower and upper motor neurons.
10. What happens at the neuromuscular junction?
