Physiology Lecture 4: Stretch Reflex

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What is the main function of muscle spindles in skeletal muscles?

To transmit nerve impulses to the CNS

To provide proprioception and sense muscle tension

To regulate muscle tone and prevent excessive stretching (correct)

To initiate muscle contraction

What type of receptors are muscle spindles classified as?

Mechanoreceptors

Nociceptors

Thermoreceptors

Proprioceptors (correct)

What is the name of the reflex contraction of a muscle when it is passively stretched?

Intrinsic reflex

Muscle spindle reflex

Myotatic reflex (correct)

Stretch reflex

What type of nerve fibers are involved in the stretch reflex pathway?

Aα (Ia) and Aβ (II) nerve fibers Signup and view all the answers

What is the function of the muscle spindle reflex?

To regulate muscle tone and prevent excessive stretching Signup and view all the answers

What is the stimulus for the stretch reflex?

Passive muscle stretch Signup and view all the answers

What is the effect of the muscle spindle reflex on the muscle?

Muscle contraction Signup and view all the answers

What is the location of muscle spindle cells within a muscle?

Within the muscle belly, parallel to the extrafusal fibers Signup and view all the answers

What type of fibers consist of the muscle spindle?

Intrafusal muscle fibers Signup and view all the answers

What is the function of the peripheral part of the muscle spindle?

Causes stretch of the central receptor area when contracted Signup and view all the answers

What is the role of the alpha motor neurons in the stretch reflex?

To transmit motor impulses to the muscle Signup and view all the answers

What is the name of the reflex that is the basis of muscle tone?

Static stretch reflex Signup and view all the answers

What is the location of the muscle spindle in the skeletal muscle?

In the fleshy parts of the muscle parallel to its fibers Signup and view all the answers

What is the function of the 1ry endings in the muscle spindle?

To transmit sensory information to the CNS Signup and view all the answers

What is the name of the fibers that have a dilated central area filled with nuclei in the muscle spindle?

Nuclear bag fibers Signup and view all the answers

What is the purpose of the stretch reflex in the muscle?

To regulate muscle tone Signup and view all the answers

What is the result of the lesion in the upper motor neuron leading to the loss of inhibition of the intact reflex arc?

Increased muscle tone (spasticity) below the level of the lesion Signup and view all the answers

What is the function of muscle tone in maintaining posture and equilibrium?

It helps in the maintenance of body posture and equilibrium Signup and view all the answers

What is the result of the lesion in the lower motor neuron on muscle tone?

Decreased muscle tone (flaccidity) at the level of the lesion Signup and view all the answers

What is the role of muscle tone in heat production and maintenance of body temperature?

It helps in the production of heat and maintenance of body temperature Signup and view all the answers

What is the dynamic stretch reflex induced by?

Tapping the tendon of the muscle with a hammer Signup and view all the answers

What is the effect of upper motor neuron lesion on deep reflexes?

Exaggeration of deep reflexes (hyperreflexia) below the level of the lesion Signup and view all the answers

What is the function of muscle tone in the maintenance of venous return and lymph flow?

It helps in the maintenance of venous return and lymph flow Signup and view all the answers

What is the role of muscle tone in preventing visceroptosis?

It helps in keeping viscera in position and preventing visceroptosis Signup and view all the answers

What type of nerve fibers are involved in the Golgi tendon organ reflex pathway?

Type Ib afferent fibers Signup and view all the answers

What is the effect of the Golgi tendon organ reflex on the muscle?

Relaxation of the same muscle Signup and view all the answers

What is the clinical significance of the Golgi tendon organ reflex?

It prevents tearing of the muscle or avulsion of its tendon Signup and view all the answers

What is the clasp-knife effect demonstrated clinically by?

Passive flexion of a spastic limb Signup and view all the answers

What is clonus?

Alternating regular rhythmic contractions with incomplete relaxations of a muscle Signup and view all the answers

What is the cause of clonus?

Upper motor neuron lesion Signup and view all the answers

What is an example of clonus?

Ankle clonus Signup and view all the answers

Where are Golgi tendon organs located?

In the tendon of skeletal muscles Signup and view all the answers

What is the primary response of a muscle spindle to a sudden stretch?

Rapid contraction followed by relaxation Signup and view all the answers

Which of the following is NOT a method to reinforce the response of tendon jerks?

Electric stimulation of the muscle Signup and view all the answers

What is the primary role of the nuclear bag receptors in muscle spindles?

To detect changes in muscle velocity Signup and view all the answers

Which of the following brain areas is involved in the facilitation of the stretch reflex?

Area 4 Signup and view all the answers

What is the term for the reflex relaxation of a muscle in response to excessive stretch or contraction?

Autogenic inhibition Signup and view all the answers

Which of the following muscles is NOT typically tested using the tendon jerk reflex?

Gastrocnemius Signup and view all the answers

What is the neural pathway involved in the stretch reflex?

Stimulus → muscle spindle → alpha motor neurons → muscle Signup and view all the answers

What is the term for the sustained contraction of a muscle in response to a maintained stretch?

Static response Signup and view all the answers