S&H Science Ch. 12 Pages 347-365 (Part 3)
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Cranial Nerve XI is called ____ and is involved in what functions?
Glossopharyngeal; taste and swallowing
The GSA fibers of CN9 are associated with what?
Sensation from the external ear
The GVE fibers of CN9 are responsible for what function?
Transmitting motor information to one of the salivary glands in the oral cavity.
The SVE fibers of CN9 are responsible for what function?
Carrying neural impulses to some of the pharyngeal muscles.
The GVA fibers of CN9 are responsible for what function?
Transmitting sensory information from the eustacian tube, posterior one third of the tongue and pharynx.
CN X is called _____ and is responsible for what functions?
Vagus; it has three branches that are essential for voice and speech production: the pharyngeal nerve, the superior laryngeal nerve, and the recurrent laryngeal nerve.
The three branches of the Vagus Nerve (CN10) are composed of what fibers?
The three branches of the Vagus Nerve (CN10) serve what functions?
- 1. Pharyngeal nerve innervates the muscles of the soft palate and pharynx.
- 2. Superior Laryngeal and 3. recurrent laryngeal nerves carry neural impulses to the laryngeal muscles.
Is the recurrent laryngeal nerve (part of CN10 Vagus) symmetrical like the other cranial nerves?
No, the nerve is of different lengths on the right and left sides of the body. This also makes the left recurent laryngeal nerve more prone to injury than the right.
The CN XII is called ____ and is responsible for what functions?
The hypoglossal nerve; innervates the muscles of the tongue.
What artery, which is patterned in a circular fashion, supplies the brain with blood?
Circle of Willis
What arteries form the Circle of Willis?
Internal carotid and vertebral arteries; anterior and posterior communicating arteries
Once inside the skull, what does the internal carotid branch into on either side of the brain?
- The ACA (supplies the frontal & parietal lobes, the corpus collosum, the basal nuclei, and internal capsule)
- The MCA (supplies blood to the temporal lobe, motor strip, ,and Wernicke's area)
The vertebral arteries, one from each side, join to form ____ artery, supplying blood to the brainstem. This artery then branches into the _____ and ____ arteries.
The basilar artery; splits again into the posterior cerebral artery (PCA) and the cerebellar artery,
The PCA provides blood to which regions of the brain?
Portions of the temporal and occipital lobes, upper midbrain, and the cerebellum.
Respiratory, laryngeal, and articulatory muscles, as well as those invloved in the maintenance of appropriate posture and balance, must be activated to do what?
Production of any phoneme (speech)
This structure of the brain controls larger groups of muscles in more widely separated parts of the body and organizes information about upcoming movements based on sensory information.
What area of the premotor cortex is involved in the planning of complex movements generated internally (like speech)?
The supplementary motor area
What is an upper motor neuron?
Nerve cells and their axons from various cortical areas that project to the brainstem and spinal cord
What is a lower motor neuron?
Nerve cell bodies and axons of the cranial and spinal nerves that connect with voluntary muscles
What are the two major pathways of the UMN?
corticospinal tract and corticonuclear (corticobulbar) tract
Fibers in the corticospinal tract synapse directly onto what?
Motor nerve cells in the spinal cord
Fibers in the corticonuclear (corticobulbar) tract arise from ____ and synapse onto what?
The face, neck, and portions of the motor cortex; synapse with motor nuclei of CN 5, 7, 10, and 12.
The corticonuclear (corticobulbar) and corticospinal tracts are collectively known also as _____
The pyramidal system
The pyramidal system is involved in controlling what functions?
fine, skilled voluntary movements, and damage can result in muscles that are weak or spastic.
The extrapyramidal system is made up of _____ , and is involved in controlling what functions?
Made of nerve pathways from the cortex to the brainstem or spinal cord that travel cicuitously via the basal nuclei and cerebellum, then synapse with spinal and brainstem motor nuclei.
Damage to the extrapyramidal system can result in what?
Abnormal involuntary movements like tics and tremors that interfere with normal voluntary control, as well as postural deficits.
What is a neuromuscular junction?
the synapse between an axon and a muscle fiber
A small depolarization of a muscle fiber is called what?
An end-plate potential
What happens when an end-plate potential reaches a critical threshold?
An action potential is generated, causing the fiber to contract
What is an innervation ratio?
The ratio of a motor neuron to the number of fibers it innervates
A motor neuron with its associated muscle fibers is called a _____
T or F: the larger the muscle, the more probability that its motor units will have large innervation ratios.
True. Large muscles, like on the legs, generate lots of force but do not require much fine neuromuscular control
Would laryngeal muscles have small or large innervation ratios?
Very small. which indicates how much fine neuromuscular control is required for phonation
What are the three types of motor units?
- 1. Type S (slow) associated with dark red muscle fibers. Don't have much force but do not fatigue easily.
- 2. Type FF (fast fatigable) associated with light-colored larger fibers that generate large amounts of force for brief amounts of time.
- 3. Type FR (fatigue resistant) generate almost as much force as FF but are more fatigue resistant (like type S)
What are the sizes of motor units, from smallest to largest?
Type S -> type FR -> type FF
The size difference plays an important role in how we regulate the muscle force needed for smooth movement
Which system does not use feedback: open loop or closed loop?
What is feedback?
Process by which the output of a system is returned to the input in order to influence the ensuing output.
In speech, this can be any type of sensory information available to the speaker (auditory, proprioceptive, tactile) that allows the individual to detect and correct any errors in his or her speech production
What is a feedforward system?
When output from one system becomes the input to a different system.
During speech, sensory info from different types of receptors is fed forward to various articulators, allowing rapid "online" adjustments to be made.
Do feedback channels operate simultaneously?
No, so sometimes you can make an error before being able to be aware of it and correct it.
What is motor equivalence?
The ability of the motor system to achieve a particular movement with a great deal of variability in the individual components of the movement.
What is efference copy?
The idea that when a neuromuscular command is sent to a muscle, a "copy" of the signal is simultaneously transmitted to various sensory systems.
Why is efference copy important?
The copies get various sensory systems ready for the anticipated consequences of the motor act.
How is efference copy transmitted?
Nerve pathways from the cortex to the cerebellum provide the cerebellum with efference copy signals from the primary motor cortex as well as sensory feedback from the primary sensory cortex.
The cerebellum then evaluates the ongoing movement and corrects any errors, projects the new information back to the motor cortex (feedback) as well as to peripheral structures via various nerve pathoways (feedforward).
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