Knowledge Test About Diseases! Trivia Quiz

Paraplegia is the most specific term that identifies the clinical picture described in the question. Paraplegia refers to paralysis of both lower extremities, which is consistent with the examination findings of the 47-year-old man who was involved in an automobile collision. This term specifically indicates the paralysis is limited to the lower limbs and does not involve the upper limbs or any other body parts. Alternating hemiplegia refers to episodes of paralysis that alternate between the left and right 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.

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 dysfunction in the lower motor neurons specifically innervating that limb. The sensory modalities in all of her limbs are retained, suggesting that the issue is not with the sensory pathways. Additionally, there is no sign of weakness in her other limbs, further indicating a localized problem in the lower motor neurons innervating the lower limb.

The most likely location of the lesion in this case is the caudal part of the pyramidal decussation. The patient's symptoms of bilateral weakness of the lower extremities without sensory deficits indicate a problem with the 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 area can lead to bilateral motor deficits, which is consistent with the patient's symptoms. The other options, such as the lateral corticospinal tract on the left or the pyramid on the right, do not account for the bilateral nature of the symptoms.

The main function of the outer hair cells is cochlear amplification. These cells are responsible for amplifying sound waves and enhancing the sensitivity and selectivity of the inner ear. They act as tiny motors, which can change their length and stiffness in response to electrical signals from the brain. This amplification helps in improving the overall hearing ability and discrimination of different sounds.

The weakness and sensory losses on the left side of the body and face indicate damage to the right side of the brain. The corticospinal fibers are responsible for motor control, so damage to the corticospinal fibers on the right side would result in weakness of the left upper and lower extremities. Therefore, the weakness in this woman is most likely due to damage to the corticospinal fibers on the right side.

The combination of the woman's tongue deviation to the right on attempted protrusion and the elevation of the soft palate and uvula to the left when saying "Ah" suggests a lesion affecting the left side of the brain. The genu of the internal capsule is a white matter pathway that carries motor fibers from the cerebral cortex to the brainstem. Lesions in this area can result in contralateral motor deficits, including tongue deviation. Therefore, a small lesion in the genu of the internal capsule on the left is the most likely explanation for the patient's symptoms.

The correct answer is corticospinal tract, thoracic, bilateral. In this case, the corticospinal tract, which is responsible for voluntary motor control, is affected. The site of injury is in the thoracic region, and the lesion is bilateral, meaning that both sides of the body are affected. This would result in paralysis or weakness in the lower limbs due to damage to the motor fibers in the corticospinal tract at the thoracic level.

Based on the given information, the elderly neighbor's difficulty in controlling the distance of his movements, as evidenced by his struggles in picking up the newspaper and grasping the brandy glass, suggests that he is experiencing dysmetria. Dysmetria is a condition characterized by inaccurate or poorly coordinated movements, often resulting in overshooting or undershooting a target. This aligns with the neighbor's description of having problems with controlling the distance of his movements.

The choroid does not directly touch the neural retina. The choroid is located between the retina and the sclera, providing nourishment to the outer layers of the retina. The choroid is mostly composed of loose connective tissue and contains many melanocytes and venous plexuses. The anterior rim of the choroid becomes the ciliary body, which is responsible for producing aqueous humor and controlling the shape of the lens.

Damage to the efferent portion of the muscle spindle would involve Ay fibers. The muscle spindle is responsible for detecting changes in muscle length and relaying this information to the central nervous system. The efferent portion of the muscle spindle consists of motor fibers that innervate the intrafusal muscle fibers within the spindle. Ay fibers are the motor fibers that specifically innervate the nuclear bag fibers, which are one of the two types of intrafusal muscle fibers found in the muscle spindle. Therefore, damage to the efferent portion of the muscle spindle would affect the Ay fibers.

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 could affect both tracts, as they are in close proximity to each other. The other options listed are not in the immediate vicinity of the lateral corticospinal tract and would therefore be less likely to be involved in a lesion in this area.

The correct answer is "Anterolateral area (area of anterolateral system)". In this scenario, the decerebrate posture and extension of the extremities indicate a dominant input to extensor motor neurons through reticulospinal fibers/tracts. The anterolateral area of the spinal cord, specifically the area of the anterolateral system, is responsible for transmitting pain and temperature sensations as well as controlling motor functions related to the maintenance of posture and movement.

The woman's difficulty in reading small print in newspapers and magazines is due to a loss of her ability to accommodate and focus on near objects. This is a common age-related condition called presbyopia, which is characterized by a gradual loss of the eye's ability to change focus from distant to near objects. Astigmatism, cataracts, optic atrophy, and macular degeneration are all different conditions that can affect vision, but they do not specifically cause a loss of accommodation and focus on near objects like presbyopia does.

The Medial Longitudinal Fasciculus carries information about the direction that the eyes should move. It yokes the cranial nerve nuclei III (Oculomotor nerve), IV (Trochlear nerve), and VI (Abducens nerve) together, and integrates movements directed by the gaze centers (frontal eye field) and information about head movement (from cranial nerve VIII, Vestibulocochlear nerve). It is an integral component of saccadic eye movements as well as vestibular-ocular and optokinetic reflexes. It also carries the descending tectospinal tract and medial vestibulospinal tracts into the cervical spinal cord and innervates some muscles of the neck and upper limbs. These bundles of axons are situated near the midline of the brainstem and are composed of both ascending and descending fibers that arise from a number of sources and terminate in different areas.

As a person ages, they may experience a loss of hearing due to damage to the hair cells in the inner ear. The hair cells at the base of the basilar membrane are responsible for detecting high frequency sounds, while the hair cells at the apex of the basilar membrane detect low frequency sounds. Since the patient cannot hear the full range of sounds, it suggests that the damage is occurring at the base of the basilar membrane, affecting the hair cells that respond to high frequency sounds.

When the ions responsible for depolarization of hair cells are added to the extracellular solution surrounding a cerebellar Purkinje cell, it would result in depolarization of the resting membrane potential of the Purkinje cell. This means that the membrane potential of the cell would become less negative, bringing it closer to the threshold for generating an action potential.

The most likely location of the lesion causing bilateral weakness of the lower limbs in a 22-year-old woman is a lesion caudal to the pyramidal decussation. The pyramidal decussation is the point where the fibers of the corticospinal tract cross over to the opposite side of the spinal cord. A lesion caudal to this decussation would affect the descending motor fibers that control the lower limbs, resulting in bilateral weakness.

The patient's symptoms of slurred speech and right-sided weakness are consistent with a lacunar infarction. Lacunar infarctions are small, localized areas of stroke caused by occlusion of a single penetrating artery. The most common location for lacunar infarctions is the internal capsule, which is a white matter tract that carries motor fibers. The left genu of the internal capsule is the most likely localization because it supplies motor fibers to the contralateral face and tongue. This explains the patient's right-sided weakness and deviation of the tongue to the right.

The semicircular canals are involved in angular acceleration or rotation. Hair cells of the right semicircular canal are excited (depolarized) when there is a rotation to the right. This rotation causes bending of the stereocilia toward the kinocilia, and this bending produces depolarization of the hair cell. The ascent in an elevator would activate the saccules, which detect linear acceleration.

Based on the given symptoms of deviation of the uvula to the left, deviation of the tongue to the right, and weakness of the facial muscles around the mouth on the right, it suggests a lesion of the right hypoglossal nerve (CN XII) and right facial nerve (CN VII). These nerves control the movement of the tongue, facial muscles, and uvula. The head turning is controlled by the sternocleidomastoid muscle, which is innervated by the spinal accessory nerve (CN XI). Therefore, the most likely additional symptom seen in this man would be an inability to turn his head to the left against resistance.