SCID 251 - Quiz L2 -spinal Cord And Spinal Reflexes

1. When you are examining a patient, you find several beats of ankle clonus. Given this finding, which one of the following are you likely to also find?

Flexor plantar response

Hyperreflexia

Muscle atrophy

Hypotonia

Fasciculations

When a patient exhibits several beats of ankle clonus, it is a sign of hyperactive reflexes. Hyperreflexia is characterized by an exaggerated response to stimuli, indicating an abnormal increase in the activity of the reflex arcs. This finding suggests that the patient may also have hyperreflexia in other parts of the body, indicating an overactive nervous system. Flexor plantar response refers to a normal response where the toes curl downwards, muscle atrophy refers to the wasting of muscle tissue, hypotonia refers to decreased muscle tone, and fasciculations refer to involuntary muscle twitches. None of these findings are directly related to ankle clonus.

Explanation

When a patient exhibits several beats of ankle clonus, it is a sign of hyperactive reflexes. Hyperreflexia is characterized by an exaggerated response to stimuli, indicating an abnormal increase in the activity of the reflex arcs. This finding suggests that the patient may also have hyperreflexia in other parts of the body, indicating an overactive nervous system. Flexor plantar response refers to a normal response where the toes curl downwards, muscle atrophy refers to the wasting of muscle tissue, hypotonia refers to decreased muscle tone, and fasciculations refer to involuntary muscle twitches. None of these findings are directly related to ankle clonus.

2. Examination of a patient with traumatic cervical cord injury revealed spasticity of legs with hyperreflexia at knee and ankle jerks. What is the best explanation of these findings?

The sensory pathways from the skin to the cerebrum have been disrupted.

A direct projection from the cerebellum to the spinal cord has been disrupted.

The spinocerebellar tracts have been disrupted.

The axons of α-motor neurons that supply extrafusal muscle fibers have been transected.

Descending motor pathways that inhibit the muscle stretch reflexes have been disrupted.

The best explanation for the findings of spasticity of legs with hyperreflexia at knee and ankle jerks is that the descending motor pathways that inhibit the muscle stretch reflexes have been disrupted. These pathways normally suppress the muscle stretch reflexes, but when they are disrupted, the reflexes become hyperactive, leading to spasticity and exaggerated reflex responses. This suggests a dysfunction in the inhibitory control of the motor pathways, rather than a disruption in sensory pathways, direct cerebellar projection, spinocerebellar tracts, or motor neuron axons.

Explanation

The best explanation for the findings of spasticity of legs with hyperreflexia at knee and ankle jerks is that the descending motor pathways that inhibit the muscle stretch reflexes have been disrupted. These pathways normally suppress the muscle stretch reflexes, but when they are disrupted, the reflexes become hyperactive, leading to spasticity and exaggerated reflex responses. This suggests a dysfunction in the inhibitory control of the motor pathways, rather than a disruption in sensory pathways, direct cerebellar projection, spinocerebellar tracts, or motor neuron axons.

3. Which is the neurotransmitter of the alpha motor motor?

Acetylcholine

Norepinephrine

Glutamate

Dopamine

GABA

Acetylcholine is the correct answer because it is the neurotransmitter responsible for transmitting signals from the alpha motor neurons to the skeletal muscles. It plays a crucial role in muscle contraction and movement. Norepinephrine, glutamate, dopamine, and GABA are neurotransmitters involved in different functions, but they are not specifically associated with the alpha motor neurons.

Explanation

Acetylcholine is the correct answer because it is the neurotransmitter responsible for transmitting signals from the alpha motor neurons to the skeletal muscles. It plays a crucial role in muscle contraction and movement. Norepinephrine, glutamate, dopamine, and GABA are neurotransmitters involved in different functions, but they are not specifically associated with the alpha motor neurons.

4. A patient had weakness on the right leg, with spasticity, hyperreflexia, and a Babinski's sign. There was also decreased pain sensation in the left leg. Where is the most likely location of the lesion?

Left internal capsule

Right side of the medulla

Right side of the cervical spinal cord

Right side of the thoracic spinal cord

Parasagittal area of the left precentral gyrus

The most likely location of the lesion is the right side of the thoracic spinal cord. This is because the patient is experiencing weakness and hyperreflexia in the right leg, which are symptoms commonly associated with a spinal cord lesion. Additionally, the decreased pain sensation in the left leg suggests that the lesion is affecting the spinal cord at a level below where the nerves for pain sensation cross over to the opposite side, which occurs in the thoracic region.

Explanation

The most likely location of the lesion is the right side of the thoracic spinal cord. This is because the patient is experiencing weakness and hyperreflexia in the right leg, which are symptoms commonly associated with a spinal cord lesion. Additionally, the decreased pain sensation in the left leg suggests that the lesion is affecting the spinal cord at a level below where the nerves for pain sensation cross over to the opposite side, which occurs in the thoracic region.

5. A patient had weakness of extension of the left elbow and hand intrinsic muscles. The left triceps jerk was absent. In the left leg, there was spasticity, hyperreflexia and Babinski's sign. Where is the most likely location of the lesion?

Left side of the spinal cord at the C7 level

Left side of the spinal cord at the C6 level

Left side of the spinal cord at the C5 level

Right internal capsule

Right precentral gyrus

The patient's symptoms indicate a combination of upper motor neuron and lower motor neuron signs. The weakness of extension of the left elbow and hand intrinsic muscles, absent left triceps jerk, spasticity, hyperreflexia, and Babinski's sign in the left leg all suggest an upper motor neuron lesion. The fact that these symptoms are on the left side of the body indicates a contralateral lesion. The most likely location of the lesion is the left side of the spinal cord at the C7 level, as this would affect the upper motor neurons that control the muscles and reflexes in both the left arm and left leg.

Explanation

The patient's symptoms indicate a combination of upper motor neuron and lower motor neuron signs. The weakness of extension of the left elbow and hand intrinsic muscles, absent left triceps jerk, spasticity, hyperreflexia, and Babinski's sign in the left leg all suggest an upper motor neuron lesion. The fact that these symptoms are on the left side of the body indicates a contralateral lesion. The most likely location of the lesion is the left side of the spinal cord at the C7 level, as this would affect the upper motor neurons that control the muscles and reflexes in both the left arm and left leg.

6. Where is the location of alpha motor neurons?

Rexed lamina II

Rexed lamina V

Rexed lamina VII

Rexed lamina IX

Rexed lamina X

Alpha motor neurons are located in Rexed lamina IX of the spinal cord. Rexed lamina IX is a specific layer within the gray matter of the spinal cord, and it contains the cell bodies of alpha motor neurons. These motor neurons are responsible for innervating skeletal muscles and are involved in voluntary movement.

Explanation

Alpha motor neurons are located in Rexed lamina IX of the spinal cord. Rexed lamina IX is a specific layer within the gray matter of the spinal cord, and it contains the cell bodies of alpha motor neurons. These motor neurons are responsible for innervating skeletal muscles and are involved in voluntary movement.

7. Which is the neurotransmitter of the upper motor neurons?

Acetylcholine

Glutamate

Dopamine

GABA

Glycine

Glutamate is the correct answer because it is the primary excitatory neurotransmitter in the central nervous system, including the upper motor neurons. It plays a crucial role in transmitting signals between neurons and is involved in various functions such as learning, memory, and motor control. Acetylcholine, dopamine, GABA, and glycine are also neurotransmitters, but they are not specifically associated with upper motor neurons.

Explanation

Glutamate is the correct answer because it is the primary excitatory neurotransmitter in the central nervous system, including the upper motor neurons. It plays a crucial role in transmitting signals between neurons and is involved in various functions such as learning, memory, and motor control. Acetylcholine, dopamine, GABA, and glycine are also neurotransmitters, but they are not specifically associated with upper motor neurons.

8. A patient was unable to walk. On examination, there was flaccid paralysis of hip flexors, hip adductors, and knee extensors. Deep tendon reflexes were absent at the knees, and hyperactive at the ankles. He had Babinski's sign bilaterally, and loss of pain and temperature sensation over both legs. Where is the most likely location of the lesion?

Bilateral lumbosacral plexus

Conus medullaris

L5 to S1 levels of the spinal cord

L1 to L3 levels of the spinal cord

Thoracic level of the spinal cord

The most likely location of the lesion is at the L1 to L3 levels of the spinal cord. This is indicated by the presence of flaccid paralysis of hip flexors, hip adductors, and knee extensors, as well as the absence of deep tendon reflexes at the knees. Additionally, the presence of Babinski's sign bilaterally and loss of pain and temperature sensation over both legs suggests a lesion at the lower spinal cord levels.

Explanation

The most likely location of the lesion is at the L1 to L3 levels of the spinal cord. This is indicated by the presence of flaccid paralysis of hip flexors, hip adductors, and knee extensors, as well as the absence of deep tendon reflexes at the knees. Additionally, the presence of Babinski's sign bilaterally and loss of pain and temperature sensation over both legs suggests a lesion at the lower spinal cord levels.