40 Questions
What is the main function of muscle spindles in skeletal muscles?
To regulate muscle tone and prevent excessive stretching
What type of receptors are muscle spindles classified as?
Proprioceptors
What is the name of the reflex contraction of a muscle when it is passively stretched?
Myotatic reflex
What type of nerve fibers are involved in the stretch reflex pathway?
Aα (Ia) and Aβ (II) nerve fibers
What is the function of the muscle spindle reflex?
To regulate muscle tone and prevent excessive stretching
What is the stimulus for the stretch reflex?
Passive muscle stretch
What is the effect of the muscle spindle reflex on the muscle?
Muscle contraction
What is the location of muscle spindle cells within a muscle?
Within the muscle belly, parallel to the extrafusal fibers
What type of fibers consist of the muscle spindle?
Intrafusal muscle fibers
What is the function of the peripheral part of the muscle spindle?
Causes stretch of the central receptor area when contracted
What is the role of the alpha motor neurons in the stretch reflex?
To transmit motor impulses to the muscle
What is the name of the reflex that is the basis of muscle tone?
Static stretch reflex
What is the location of the muscle spindle in the skeletal muscle?
In the fleshy parts of the muscle parallel to its fibers
What is the function of the 1ry endings in the muscle spindle?
To transmit sensory information to the CNS
What is the name of the fibers that have a dilated central area filled with nuclei in the muscle spindle?
Nuclear bag fibers
What is the purpose of the stretch reflex in the muscle?
To regulate muscle tone
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
What is the function of muscle tone in maintaining posture and equilibrium?
It helps in the maintenance of body posture and equilibrium
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
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
What is the dynamic stretch reflex induced by?
Tapping the tendon of the muscle with a hammer
What is the effect of upper motor neuron lesion on deep reflexes?
Exaggeration of deep reflexes (hyperreflexia) below the level of the lesion
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
What is the role of muscle tone in preventing visceroptosis?
It helps in keeping viscera in position and preventing visceroptosis
What type of nerve fibers are involved in the Golgi tendon organ reflex pathway?
Type Ib afferent fibers
What is the effect of the Golgi tendon organ reflex on the muscle?
Relaxation of the same muscle
What is the clinical significance of the Golgi tendon organ reflex?
It prevents tearing of the muscle or avulsion of its tendon
What is the clasp-knife effect demonstrated clinically by?
Passive flexion of a spastic limb
What is clonus?
Alternating regular rhythmic contractions with incomplete relaxations of a muscle
What is the cause of clonus?
Upper motor neuron lesion
What is an example of clonus?
Ankle clonus
Where are Golgi tendon organs located?
In the tendon of skeletal muscles
What is the primary response of a muscle spindle to a sudden stretch?
Rapid contraction followed by relaxation
Which of the following is NOT a method to reinforce the response of tendon jerks?
Electric stimulation of the muscle
What is the primary role of the nuclear bag receptors in muscle spindles?
To detect changes in muscle velocity
Which of the following brain areas is involved in the facilitation of the stretch reflex?
Area 4
What is the term for the reflex relaxation of a muscle in response to excessive stretch or contraction?
Autogenic inhibition
Which of the following muscles is NOT typically tested using the tendon jerk reflex?
Gastrocnemius
What is the neural pathway involved in the stretch reflex?
Stimulus → muscle spindle → alpha motor neurons → muscle
What is the term for the sustained contraction of a muscle in response to a maintained stretch?
Static response
Learn about the stretch reflex, its types, and the neurophysiological basis of muscle tone and tendon jerk. Understand the role of muscle spindles in skeletal muscle tissue.
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