MOTOR SYSTEM - INTRO
Introduction
The motor system is the part of the nervous system responsible for initiating, controlling, and refining
voluntary and involuntary movements. It integrates sensory inputs, plans the movement, activates the
correct muscles, and ensures smooth, coordinated execution.
Key Roles of the Motor System
Initiation of movement – transforming intention into action.
Coordination – ensuring muscle groups work together efficiently.
Regulation of muscle tone – maintaining readiness for movement.
Postural control – keeping balance during static and dynamic activities.
Reflex actions – providing rapid responses to sensory stimuli.
The motor systeem has been shown to control voluntary movement. In voluntary movement, a muscle
is made to contraact via impulses reaching it through;
Synasing directly on the alpha motor neurons - This has the advantage of speed and specificity.
N/B. Motor neurons to skeletal muscles can be classified as alpha and gamma neurons ....
Synapsing on the muscle spindles via gamma motor neurons, thereby influencinfg the alpha
motor neurons indirectly. N/B. This path as well as the one above are seen to operate together
(i.e, alpha-gamma co-activation)
Synapsing on the interneurons; the same ones subserving the local reflexes. N/B. Although this
path is not as fast as directly influencng motor neurons, it has the advantage of cordination,
which is built into the interneuron network.
The degree with which these 3 mechanisms are employed is dependent on; the nature of motor
activity to be performed, and the descending pathway that is utilized. The descending pathways
are.....
Structural Components
The motor system is organized into:
1. Upper motor neurons (UMNs) – originate in the motor cortex or brainstem; they do not directly
contact muscles but control LMNs. The UMN majorly consist of neurons of the pyramidal system,
extrapyramidal system and cerebelum
2. Lower motor neurons (LMNs) – located in the anterior horn of the spinal cord or cranial nerve motor
nuclei; directly innervate skeletal muscle.
3. Descending motor pathways – such as the corticospinal (aka. Pyramidal) and corticobulbar (aka.
rubrospinal, reticulospinal, tectospinal, vestibulospinal) tracts.
Introduction
The motor system is the part of the nervous system responsible for initiating, controlling, and refining
voluntary and involuntary movements. It integrates sensory inputs, plans the movement, activates the
correct muscles, and ensures smooth, coordinated execution.
Key Roles of the Motor System
Initiation of movement – transforming intention into action.
Coordination – ensuring muscle groups work together efficiently.
Regulation of muscle tone – maintaining readiness for movement.
Postural control – keeping balance during static and dynamic activities.
Reflex actions – providing rapid responses to sensory stimuli.
The motor systeem has been shown to control voluntary movement. In voluntary movement, a muscle
is made to contraact via impulses reaching it through;
Synasing directly on the alpha motor neurons - This has the advantage of speed and specificity.
N/B. Motor neurons to skeletal muscles can be classified as alpha and gamma neurons ....
Synapsing on the muscle spindles via gamma motor neurons, thereby influencinfg the alpha
motor neurons indirectly. N/B. This path as well as the one above are seen to operate together
(i.e, alpha-gamma co-activation)
Synapsing on the interneurons; the same ones subserving the local reflexes. N/B. Although this
path is not as fast as directly influencng motor neurons, it has the advantage of cordination,
which is built into the interneuron network.
The degree with which these 3 mechanisms are employed is dependent on; the nature of motor
activity to be performed, and the descending pathway that is utilized. The descending pathways
are.....
Structural Components
The motor system is organized into:
1. Upper motor neurons (UMNs) – originate in the motor cortex or brainstem; they do not directly
contact muscles but control LMNs. The UMN majorly consist of neurons of the pyramidal system,
extrapyramidal system and cerebelum
2. Lower motor neurons (LMNs) – located in the anterior horn of the spinal cord or cranial nerve motor
nuclei; directly innervate skeletal muscle.
3. Descending motor pathways – such as the corticospinal (aka. Pyramidal) and corticobulbar (aka.
rubrospinal, reticulospinal, tectospinal, vestibulospinal) tracts.
