|SPH405 : The Class : Efferent Systems : Descending Tracts : Online Lesson 3|
The Extrapyramidal Tracts and Communicative Functions
GOAL: to apply the anatomy and physiology of the extrapyramidal tracts to the study of communicative functions.
OBJECTIVES: After reading, lecture and study, the students will...
Distinguish the extrapyramidal tracts from the pyramidal tracts.
Differentiate Alpha and Gamma Lower Motor Neurons.
Name and describe the functions of the Tectospinal, Rubrospinal; Vestibulospinal; and Reticulospinal components systems of the extrapyramidal tracts.
Apply the functions of the Extrapyramidal Tracts to the production of speech.
Identify the Basal Ganglia and their component nuclei.
Apply the function of the Basal Ganglia to natural speech production.
Apply the function of the Reticular System to human communication.
They are distinct from the pyramidal Tracts in that their function is largely UNCONSCIOUS.
The Extrapyramidal System is also PASSIVE. These tracts depend upon input from the brain as well as the skeletal muscles to function properly.
They originate in DIFFUSE areas of the central nervous system.
Alpha motor neurons receive input directly from the central nervous system.
Gamma motor neurons receive unconscious input from muscle spindles.
The Extrapyramidal tracts include the TECTOSPINAL tracts, the RUBROSPINAL tracts, the VESTIBULOSPINAL tracts and the RETICULOSPINAL tracts.
The TECTOSPINAL tracts control sudden reflexive responses to high intensity sensory stimuli.
The RUBROSPINAL tract activates the postural support muscles
The extrapyramidal tracts concerning posture apply to language development inasmuch as they allow normal ambulation for experiences with the physical world.
RETICULOSPINAL Tracts regulate muscle tone and inhibit reflex contractions.
These extrapyramidal tracts permit orientation and awareness of the individual's universe.
The Reticular Formation is a diffuse network of neural circuits. Some authors (see Hamilton, p. 540) avoid enumeration of the nuclei, since the network is so diffuse.
The Extrapyramidal system relies heavily on input from the BASAL GANGLIA (Striate Bodies; corpora striatum; basal nuclei ) and the reticular formation. These groups of specialized neurons are Nuclei of the sub cortical levels of the cerebral hemispheres. They are distinguished by their special neurotransmitters.
The "Three Masses" are:
The "Associated Masses" are:
Like Cerebellar neurons, the nuclei of the Basal Ganglia do not initiate muscular contractions.
They react to input from the Cerebral cortex; Cerebellum and Reticular Formation
They function to inhibit reflexes and regulate muscle activity
Once you have finished you should:
E-mail Bill Culbertson
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