Block 5 Neuro Motor Systems MCQ's

Paraplegia is the most specific term that identifies the clinical picture described in the question. Paraplegia refers to the paralysis of both lower extremities, which is consistent with the examination findings of the 47-year-old man. Alternating hemiplegia refers to paralysis that alternates between the right and left sides of the body, hemiplegia refers to paralysis of one side of the body, monoplegia refers to paralysis of a single limb, and quadriplegia refers to paralysis of all four limbs. Therefore, paraplegia is the most appropriate term in this case.

Hyporeflexia is characteristic of lower motor neuron damage. Lower motor neurons are responsible for transmitting signals from the central nervous system to the muscles, and damage to these neurons can result in a decrease in reflexes. This can manifest as reduced or absent reflex responses when the affected limb is stimulated. The other options, such as hyperreflexia, increased tone, spastic paralysis, and increased muscle mass, are more indicative of upper motor neuron damage.

The correct answer is Corona radiata. The fibers that fan out from the internal capsule into the white matter of the hemisphere are known as the corona radiata. The corona radiata is a collection of nerve fibers that connect the cerebral cortex to other parts of the brain and spinal cord. It is involved in transmitting sensory and motor information between different regions of the brain. The other options listed, such as the cingulum, genu of the corpus callosum, superior longitudinal fasciculus, and uncinate fasciculus, are not specifically associated with fibers that fan out from the internal capsule.

Based on the given information, the elderly neighbor is experiencing difficulties in controlling the distance of his movements, which is a characteristic symptom of dysmetria. Dysmetria is a neurological condition that affects the coordination of movements, causing inaccurate judgment of distance and over or undershooting of targets. This explains why the neighbor struggles to pick up the newspaper and grasp the brandy glass correctly.

Damage to the corticospinal fibers would most likely explain the deficit of weakness of the left upper and lower extremities. The corticospinal fibers are responsible for the voluntary movement of the limbs, and damage to these fibers can lead to weakness or paralysis on the opposite side of the body. In this case, the infarcted area in the medulla is affecting the corticospinal fibers, resulting in weakness on the left side.

The correct answer is upper motor neuron lesion, genu of internal capsule, right. This is because the patient is experiencing drooping in her left lower facial muscles, which indicates a lower motor neuron lesion. The forehead remains unaffected, indicating an upper motor neuron lesion. The site of the lesion is the genu of the internal capsule, which is responsible for controlling the facial muscles. The side of the lesion is right, as the symptoms are occurring on the left side of the face.

The correct answer is Syringomyelia, Spinothalamic tract. Syringomyelia is a disorder characterized by the formation of a cyst, called a syrinx, within the spinal cord. This cyst can compress and damage the surrounding structures, including the Spinothalamic tract. The Spinothalamic tract is responsible for transmitting pain and temperature sensations from the body to the brain. In this case, the presence of the cyst at the cervical level of the spinal cord is causing a "cape-like" loss of sensation to the back and arms, which is consistent with the involvement of the Spinothalamic tract.

The woman is displaying upper limb flexion and lower limb extension. Lesions rostral to the red nucleus can cause a condition known as decerebrate rigidity, which is characterized by extension of the upper limbs and extension of the lower limbs. This is due to disruption of the normal inhibitory pathways that control muscle tone and posture. The other symptoms listed, such as lower extremity weakness, weakness of the masticatory muscles, and deviation of the tongue on protrusion, are not typically associated with lesions rostral to the red nucleus.

The cell bodies of lower motor neurons innervating the lower limb are located in Lamina VIII, IX. This is supported by the fact that the patient is unable to move her left leg, indicating a lower motor neuron lesion. The sensory modalities in all of her limbs are retained, suggesting that the lesion is specific to the motor neurons. The absence of weakness in her other limbs further supports the localization of the lesion to the lower limb. Lamina VIII and IX are known to contain cell bodies of lower motor neurons that control muscle movement.

The correct answer is Corticospinal tract, thoracic, bilateral. This means that the tract affected is the corticospinal tract, the site of injury is in the thoracic region, and the type of lesion is bilateral. This suggests that the motor bike accident caused damage to the corticospinal tract in the thoracic region on both sides of the body, resulting in paraplegia.

The patient's symptoms, including weakness on the left side of the body, sensory losses on the left side, and a visual deficit in both eyes, suggest damage to the right side of the brain. The anterior choroidal artery supplies blood to the internal capsule, which contains the corticospinal fibers. Damage to the corticospinal fibers on the right side would result in weakness on the left side of the body, explaining the patient's symptoms. Therefore, the weakness of the extremities in this woman is most likely due to damage to the corticospinal fibers on the right.

The most likely location of the lesion in this case is the caudal part of the pyramidal decussation. This is because the patient has bilateral weakness of his lower extremities, which suggests a lesion affecting the descending motor pathways. The pyramidal decussation is the site where the fibers of the corticospinal tracts cross over from one side of the brain to the opposite side of the spinal cord. Lesions in this region can result in bilateral motor deficits, which is consistent with the patient's presentation.

When tapping the patellar tendon, the resulting knee jerk reflex is activated by the muscle spindle. Muscle spindles are sensory receptors located within the muscle fibers and are responsible for detecting changes in muscle length and the rate of change. They play a crucial role in the stretch reflex, which helps to maintain posture and prevent overstretching of muscles. When the patellar tendon is tapped, the muscle spindle is activated, sending sensory information to the spinal cord, which then triggers the reflexive contraction of the quadriceps muscle, resulting in the knee jerk reflex.

The neurological examination findings indicate that the patient has weakness of the right lower extremity. This suggests damage to a motor pathway that controls voluntary movement. The corticospinal tract is responsible for voluntary movement and runs on the opposite side of the body. Therefore, damage to the right lateral corticospinal tract would correlate with weakness of the right lower extremity. The other tracts mentioned do not control voluntary movement or are on the opposite side of the body, so they would not be responsible for the observed weakness.

A lesion caudal to the pyramidal decussation is the most likely location of the lesion causing bilateral weakness of the lower limbs. The pyramidal decussation is the point where the fibers of the corticospinal tract cross over from one side of the brain to the opposite side of the spinal cord. Lesions rostral to the decussation would affect the contralateral side of the body, while lesions caudal to the decussation would affect the ipsilateral side of the body. Therefore, a lesion caudal to the pyramidal decussation would result in bilateral weakness of the lower limbs.

The extension of the man's extremities indicates that there is a dominant input to extensor motor neurons through reticulospinal fibers/tracts. The anterolateral area, also known as the area of the anterolateral system, specifically describes the position of these activated fibers within the spinal cord. This area is responsible for transmitting pain and temperature sensations. Therefore, the activation of these fibers in the anterolateral area suggests that the man may be experiencing pain or discomfort as a result of his head injury.

A lesion located in the immediate vicinity of the lateral corticospinal tract would most likely involve the rubrospinal tract. The rubrospinal tract is located adjacent to the lateral corticospinal tract in the spinal cord. Lesions in this area can affect the rubrospinal tract, which is responsible for motor control and coordination. The other options, such as the anterolateral system, anterior spinocerebellar tract, gracile fasciculus, and medial longitudinal fasciculus, are not in close proximity to the lateral corticospinal tract and would not be directly affected by a lesion in that area.

The glioma in the white matter between the lenticular nucleus and the thalamus on the right side of the brain is compressing the posterior limb of the internal capsule. This can explain the marked weakness on the left side of the woman's body, as the posterior limb of the internal capsule contains descending motor fibers that control movement on the opposite side of the body.

The most likely level of damage to the spinal cord resulting from the fracture to the vertebral column in this man is T8 on the right. This is indicated by the loss of pain and thermal sensations on the left side beginning at the level of the umbilicus, which is consistent with a lesion at the T8 dermatome. The weakness of the right lower extremity suggests involvement of the descending corticospinal tract, which is also consistent with a T8 level of damage.

The correct answer is "Decerebrate; Medial reticulospinal and lateral vestibulospinal tract." Decerebrate rigidity is characterized by extension of both upper and lower limbs. This type of rigidity is caused by damage to the brainstem, specifically the midbrain. The involvement of the medial reticulospinal and lateral vestibulospinal tracts in the extension of the limbs suggests dysfunction in these tracts due to the lesion in the midbrain.

The combination of a deviated tongue to the right on attempted protrusion and an elevated soft palate and uvula to the left when saying "Ah" suggests a lesion in the left side of the brain. The genu of the internal capsule contains fibers that control the muscles of the face, tongue, and throat. Therefore, a small lesion in the genu of the internal capsule on the left side could result in these specific deficits.

Damage to the efferent portion of the muscle spindle would involve Ay fibers. The muscle spindle is a sensory organ located within skeletal muscles that detects changes in muscle length and tension. It consists of specialized muscle fibers called intrafusal fibers, which are innervated by both sensory (afferent) and motor (efferent) fibers. The Ay fibers are the efferent fibers that innervate the muscle spindle and are responsible for adjusting its sensitivity and maintaining muscle tone. Therefore, damage to the efferent portion of the muscle spindle would affect the Ay fibers.

The patient's symptoms of slurred speech and right-sided weakness suggest a stroke. Lacunar infarctions are small, deep infarcts that commonly occur in the internal capsule. The internal capsule contains ascending and descending fibers that connect the cerebral cortex with the brainstem and spinal cord. The left genu of the internal capsule is responsible for motor control, and damage to this area can result in weakness on the opposite side of the body. Therefore, the most likely localization of the lacunar infarction in this patient is the left genu of the internal capsule.

The patient's symptoms of deviation of the uvula to the left on phonation, deviation of the tongue to the right on protrusion, and weakness of the facial muscles around the mouth on the right suggest a lesion in the right cranial nerve XII (hypoglossal nerve) and cranial nerve VII (facial nerve). These nerves innervate the muscles responsible for movement of the tongue, uvula, and facial muscles. The most likely additional symptom that would be seen in this man is an inability to turn his head to the left against resistance, indicating weakness or paralysis of the right sternocleidomastoid muscle, which is innervated by the right cranial nerve XI (accessory nerve).