L6b_Somatosensory System 14 Quiz

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What type of response is exhibited by primary endings of group Ia fibers?

Neither phasic nor tonic response

Tonic response only

Both phasic and tonic response (correct)

Phasic response only

Where are secondary endings of group II fibers typically located?

At the central region of the intrafusal fiber in forms of a spray (correct)

At the peripheral region of the intrafusal fiber in forms of a spiral

At the central region of each intrafusal fiber in forms of a spiral

At the peripheral region of the intrafusal fiber in forms of a spray

What is the function of gamma motor neurons in the muscle spindle?

To innervate the sensory receptors in the muscle spindle

To supply extrafusal muscle fibers

To regulate the muscle spindle only during muscle contraction

To supply intrafusal muscle fibers (muscle spindles) (correct)

What sequence of events occurs in the muscle spindle when extrafusal muscle fibers are stretched?

Stretching of intrafusal muscle fiber - Ia fibers fire - II fibers fire - γ motor neurons fire - α motor neurons fire Signup and view all the answers

What is the function of γ dynamic axons in the muscle spindle?

Control velocity of change in muscle length Signup and view all the answers

What is the role of muscle spindles in skeletal muscle?

Detecting muscle stretch, tension, and rate of change in muscle length Signup and view all the answers

What is the result of α-γ co-activation in the muscle spindle?

Intrafusal fibers contract simultaneously with extrafusal fibers Signup and view all the answers

How are intrafusal muscle fibers structured?

They are only contractile at the ends, not the central region Signup and view all the answers

Which type of intrafusal fiber is responsible for detecting the velocity of muscle stretch?

Nuclear bag fiber Signup and view all the answers

What is the function of efferent innervations in muscle spindles?

To contract extrafusal muscle fibers Signup and view all the answers

What initiates a reflex that resists rapid muscle stretch?

Muscle spindles Signup and view all the answers

Where are the muscle fibers found inside the muscle spindle?

Only at the ends, away from the central region Signup and view all the answers

What happens to the spindle sensory receptors during passive stretch?

They elongate and become activated Signup and view all the answers

Which neurons are responsible for contracting extrafusal muscle fibers?

α-motor neurons Signup and view all the answers

What effect does the firing of γ-motor neurons have on the intrafusal fibers?

It induces contraction Signup and view all the answers

In a normal neuromuscular system, what happens when α-motor neurons fire and γ-motor neurons do not?

The intrafusal central region relaxes Signup and view all the answers

What is the role of type Ia afferent neurons in the muscle spindle mechanism?

Detection of passive stretch Signup and view all the answers

How does the firing of γ-motor neurons help in maintaining sensory endings' ability to indicate stretch?

It contracts intrafusal fibers Signup and view all the answers

What is the consequence of the spindle sensory receptors being inactive during muscle stretch?

Loss of proprioceptive feedback Signup and view all the answers

What type of neurons are responsible for sensory innervation in the muscle spindle?

Afferent neurons Signup and view all the answers

How are proprioceptive signals transmitted to the cerebellum regarding muscle stretch?

Using high fidelity pathways Signup and view all the answers

What function do γ-motor neurons serve when α-motor neurons to extrafusal muscles fire?

Contract intrafusal fibers Signup and view all the answers