Dr Gawad Online MCQ Exam. Stretch Reflex, UMNL & LMNL

2.

Regarding vascular lesion in the internal capsule, which is true:

It affects a localized group of muscles
Contralateral muscles are hypertonic
It affects muscle of the ipsilateral side
None of the above

Correct Answer

A. Contralateral muscles are hypertonic

Explanation

In vascular lesions of the internal capsule, the correct statement is that contralateral muscles are hypertonic. The internal capsule is a crucial pathway that carries motor fibers from the cerebral cortex to the spinal cord, controlling voluntary movements. When a vascular lesion occurs in this area, it can disrupt the motor pathway, leading to muscle abnormalities. In this case, the contralateral side of the body, opposite to the lesion, experiences increased muscle tone or hypertonicity. This is known as spasticity and is a common symptom of damage to the internal capsule.

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1

3.

Regarding stretch reflex which of the following is false:

Nuclear bag fiber is responsible for tendon jerk reflex.
Gamma efferent neuron is considered as the efferent of stretch reflex.
It is a monosynaptic reflex.
After discharge is not from the properties of this reflex.

Correct Answer

A. Gamma efferent neuron is considered as the efferent of stretch reflex.

Explanation

The correct answer is "Gamma efferent neuron is considered as the efferent of stretch reflex." This statement is false because the efferent of the stretch reflex is actually the alpha motor neuron, not the gamma efferent neuron. The gamma efferent neuron is responsible for adjusting the sensitivity of the muscle spindle, but it is not directly involved in the stretch reflex itself.

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4.

Male patient has a vascular lesion of internal capsule, which of the following may be found in this patient:

Hypotonia.
Deep reflexes are absent
No muscle wasting
All of the above

Correct Answer

A. No muscle wasting

Explanation

A vascular lesion of the internal capsule can result in damage to the motor pathways, leading to various motor deficits. Hypotonia, or decreased muscle tone, may be present due to the disruption of signals from the brain to the muscles. Deep reflexes may also be absent because the lesion can affect the transmission of sensory information to the spinal cord. The absence of muscle wasting suggests that there is no degeneration or atrophy of the muscles, which further supports the possibility of a vascular lesion. Therefore, all of the given options may be found in a male patient with a vascular lesion of the internal capsule.

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5.

About stretch reflex:

The nuclear bag stimulation leads to dynamic stretch reflex.
The gamma neuron is the centre of the reflex.
The nuclear chain afferent is of type II fibers only.
None of the above

Correct Answer

A. The nuclear bag stimulation leads to dynamic stretch reflex.

Explanation

The correct answer is "the nuclear bag stimulation leads to dynamic stretch reflex." This is because the nuclear bag fibers are responsible for detecting changes in muscle length and initiating the stretch reflex. When these fibers are stimulated, they send signals to the spinal cord, which then activates the motor neurons to contract the muscle and prevent overstretching. The gamma neuron, on the other hand, is responsible for regulating the sensitivity of the muscle spindle, but it is not the center of the reflex. The statement about the nuclear chain afferent being of type II fibers only is incorrect, as both type I and type II fibers can be found in the nuclear chain.

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6.

Servo-assistant device means

Increased activity of both primary and secondary afferent nerve endings from muscle spindle
Absence of reciprocal innervation in positive supporting reaction
Both α- and γ-motor neurons are activated by descending stimulatory tracts
All of the above

Correct Answer

A. Both α- and γ-motor neurons are activated by descending stimulatory tracts

Explanation

The correct answer is "both α- and γ-motor neurons are activated by descending stimulatory tracts." This means that a servo-assistant device activates both α- and γ-motor neurons through descending stimulatory tracts. α-motor neurons innervate extrafusal muscle fibers, which are responsible for generating force in muscles, while γ-motor neurons innervate intrafusal muscle fibers, which are involved in muscle spindle function. Activation of both types of motor neurons allows for precise control and coordination of muscle activity, which is essential for the functioning of a servo-assistant device.

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7.

All of the following are related to stretch reflex except:

Monosynaptic
No after discharge
No irradiation
No reciprocal innervations.

Correct Answer

A. No reciprocal innervations.

Explanation

The stretch reflex is a monosynaptic reflex that occurs when a muscle is stretched, causing a contraction to prevent overstretching. It does not involve after discharge, which is the continuation of neural activity after the stimulus has ended. It also does not involve irradiation, which is the spread of reflex activity to other muscles. However, it does involve reciprocal innervation, which is the simultaneous contraction of one muscle and relaxation of its antagonist. Therefore, the correct answer is "no reciprocal innervations."

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8.

The main stimulus of Golgi tendon organ is:

Increase muscle tetanic activity
Increase in muscle tension
Increased uscle period of contraction
None of the above

Correct Answer

A. Increase in muscle tension

Explanation

The Golgi tendon organ is a sensory receptor located in the tendons that connect muscles to bones. It is responsible for detecting changes in muscle tension. When muscle tension increases, the Golgi tendon organ is stimulated and sends signals to the brain, which allows for the regulation and control of muscle contraction. Therefore, the correct answer is "Increase in muscle tension."

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9.

Which of the following is true regarding UMNL & LMNL

LMNL is characterized by hypertone of the muscle
UMNL may be ipsilateral if the lesion in the descending tracts is at the level of the spinal cord
Deep reflexes exaggerated with appearance of clonus in LMNL
Plantar reflex may be absent in UMNL

Correct Answer

A. UMNL may be ipsilateral if the lesion in the descending tracts is at the level of the spinal cord

Explanation

UMNL stands for Upper Motor Neuron Lesion, while LMNL stands for Lower Motor Neuron Lesion. The given statement is true because if the lesion in the descending tracts is at the level of the spinal cord, the UMNL can be ipsilateral, meaning it affects the same side of the body. This is because the descending tracts in the spinal cord carry motor signals from the brain to the muscles, and if there is a lesion at the level of the spinal cord, it can disrupt the motor signals on the same side.

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Dr Gawad Online MCQ Exam. Stretch Reflex, Umnl & Lmnl

Which of the following is true regarding lower motor neuron lesion:

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Regarding vascular lesion in the internal capsule, which is true:

Regarding stretch reflex which of the following is false:

Male patient has a vascular lesion of internal capsule, which of the following may be found in this patient:

About stretch reflex:

Servo-assistant device means

All of the following are related to stretch reflex except:

The main stimulus of Golgi tendon organ is:

Which of the following is true regarding UMNL & LMNL