Neurophys III Flashcards
What are the three types of intrafusal fibers?
Dynamic nuclear bag
Static nuclear bag
Nuclear chain fibers
Primary ending Group 1A fibers can be found innervating which intrafusal fibers and measure what responses?
One per muscle spindle controlling nuclear bag and chain fibers.
Measure static and dynamic fire patterning. AKA measure rate of change and current length.
Secondary ending Group II fibers can be found on which intrafusal fibers and measures what fire patterning?
Can be found on nuclear chain fibers only. Measures STATIC RESPONSE ONLY giving information on muscle length only, not change in muscle length.
Gamma effrent fibers provide what information?
Provide fusimotor drive to muscle spindles.
Gamma-dynamic fibers provide what sort of innervation?
These innervate dynamic nuclear bags.
Gamma static fibers provide what sort of innervation?
End on nuclear chain fibers and static nuclear bags.
Skeletofusimotor fibers (Beta innervation) provide what sort of innervation?
Some motorneurons innervate both extrafusal and intrafusal fibers.
When comparing alpha motor neurons and gamma motor neurons, which is quicker?
Alpha motor neurons are heavily myelinated and act quicker than the lightly myelinated gamma motor neurons.
What is the function of coactivation of alpha and gamma motorneurons?
Gamma innervation insures taughtness of intrafusal fibers for immediate responses to contractions caused by alpha innervation.
Thus smooth movement is dependent on both innervation neurons.
Static response of the muscle spindle is carried out by which fibers and accomplishes what goal?
Firing patterns signal ammount of stretch or muscle strength.
Uses Tye 1a and type II fibers.
Dynamic response of the muscle spindle is carried out by which fibers and accomplishes what goal?
Firing pattern signals measures rate at which muscle is being stretched or changes in muscle length.
Carried out by Type Ia fibers only.
Describe the correlation of gamma motor neurons with rate of muscle spindle cell firing.
The rate of muscle spindle cell firing depends on both muscle length and the level of gamma activation of the intrafusal muscle fibers.
This is known as the fusimotor drive.
Where do the type IA fibers synapse in the phasic and tonic stretch reflexes?
Synaps on the alpha motor neuron of the homonymous and synergist muscles.
Which stretch reflex are the type II fibers associated with and what function do they have in that reflex?
Involved in the tonic stretch reflex.
Synapse directly on alpha motor units of the homonymous muscle.
Phasic stretch reflex is initiated by what sort of test?
Tapping on the tendon with a reflex hammer.
This is known as the deep tendon reflex and can demonstrate LMN vs UMN porblems.
