131. An 18-year-old man receives a knife wound in his right arm, which partially severs the peripheral nerve. Afterward, he complains of some loss of sensation. A neurological examination indicates loss of ability to experience vibration sensation, loss of two-point discrimination, and some loss of pain sensation. Which structure that mediates two-point discrimination and vibration sensation is affected by the injury?
132. A middle-aged woman is admitted to the hospital after suffering a stroke limited to the motor cortex. The patient presents with spasticity and paralysis. Which labeled area degenerated as a result of the stroke?
133. An elderly man is brought to the emergency room after fainting at his home. Magnetic resonance imaging (MRI) suggests the presence of a small stroke limited to the medial aspect of the rostral part of the midbrain tegmentum. Which labeled area is most likely affected by the stroke?
134. A 30-year-old man is brought to the emergency room after sustaining a work-related injury that damaged part of his spinal cord. A neurological examination reveals considerable loss of extensor muscle function. Damage to which labeled area could account for this defect?
135. A 58-year-old woman is admitted to a local hospital following reports by her family that she had recent experiences of falling, as well as displaying lack of coordination of movement. Her neurological examination reveals primarily a gait ataxia, coupled with some dysarthria and nystagmus. Which labeled area is most likely affected?
136. A 30-year-old man is referred to a neurologist after complaining of severe pain in his back. The neurologist prescribes a new drug whose actions have been shown to block the release of the neurotransmitter from the terminal endings of first-order neurons in the spinal cord, thus preventing transmission of pain impulses to the brain. Which labeled area in the figure did this drug act upon to reduce pain transmission?
137. A 64-year-old woman suffers from a massive stroke of the motor regions of the cerebral cortex, causing loss of voluntary movement. Among the fiber pathways that are affected by the stroke is a component that passes through the ipsilateral spinal cord. Which labeled area is most likely affected by the stroke?
138. An 18-year-old man suffers a serious football injury that leaves him temporarily motionless on the ground after he was tackled by two players of the opposing team. A neurological analysis reveals significant compression of the spinal cord, in particular along its lateral extent. Examination reveals clinical signs such as hypotonia, decreased tendon reflexes, and some ataxia. Which labeled area is most likely involved?
Questions 139 to 141
Each of the following cases may be caused by a lesion at a particular site. Identify the location of the causative lesions in each of the cases described next. Each lettered option may be used once, multiple times, or not at all.
139. A patient suffering from a disease of unknown etiology reports that he cannot move his hands and arms. Neurological analysis revealed a flaccid paralysis of the upper limbs, with diminished reflex activity in these limbs.
140. A 76-year-old woman is rushed to an emergency room after she was found unconscious in her apartment. Sometime later, she regains consciousness but cannot move her right arm or hand. Further neurological analysis reveals hyperreflexia and hypertonia in the affected limb.
141. A 25-year-old man suffers a stab wound in an assault and is taken to the emergency room for treatment. A physical examination indicates that the knife penetrated the spinal cord. Neurological examination reveals ataxia during attempts to walk. The other aspects of movement appear normal.
142. A 24-year-old man becomes intoxicated and gets into a bar fight, during which he is stabbed in the back. He is taken to the emergency room and, following a thorough neurological examination, it is determined that the knife wound destroyed the right half of the spinal cord at the level of the lower cervical cord. Which of the following deficits will most likely result from this knife wound?
a. Impaired bladder functions only
b. Impaired movements of the lower limb only
c. Impaired movements of the upper limb only
d. Loss of sensory functions of the lower limb only
e. Loss of sensory and motor functions of upper and lower limbs
143. A 48-year-old man suffers a brainstem stroke that results in a UMN syndrome, with loss of voluntary movement of the limbs, hyperreflexia, and hypertonia. With respect to hyperreflexia and hypertonia, which of the following explanations can best explain these symptoms?
a. Abnormal stimulation of unmyelinated C fibers
b. Sequential excitation and inhibition of 1A fibers
c. Abnormal stimulation of gamma motor neurons
d. Sequential excitation and inhibition of alpha motor neurons
e. Abnormal stimulation of general visceral efferent fibers
144. An individual suffers a severe injury, with crushing of the peripheral nerves that normally enter the spinal cord at levels C7 to T1. There is both motor and sensory loss. Which of the following regions would most likely be affected by the injury?
a. Back of the head
b. Neck
c. Shoulder
d. Hand
e. Back
145. Efforts were made by a pharmaceutical company to develop a drug that reduces or eliminates pain associated with neuropathies. The approach was to utilize a neurotransmitter-receptor blocker against the neurotransmitter released by the first-order pain pathway. The drug under development is an antagonist against which of the following neurotransmitters?
a. Enkephalins
b. Acetylcholine (ACh)
c. Substance P
d. γ-Aminobutyric acid (GABA)
e. Serotonin
146. A 56-year-old woman is examined by a neurologist because she cannot recognize any pain sensation in her arms or legs. It is determined that a viral disorder has selectively affected the sensory fibers entering the spinal cord and which pass through Lissauer marginal zone. Which of the following statements correctly characterizes the fibers in this region?
a. They mediate unconscious proprioception.
b. This zone is composed of coarse, heavily myelinated fibers.
c. These fibers synapse in the region of the substantia gelatinosa.
d. These fibers directly activate homonymous alpha motor neurons that supply extensor muscles.
e. Cells in this zone typically project to thalamic nuclei.
147. A 63-year-old man is involved in an automobile accident and sustains a small peripheral nerve injury. The damage involves some of the axons that enter the spinal cord at L1, affecting principally the fibers that innervate the nucleus dorsalis of Clarke. Which of the following is the primary dysfunction resulting from this injury?
a. Loss of autonomic functions
b. Loss of unconscious proprioceptive information
c. Loss of pain and temperature sensation
d. UMN paralysis
e. LMN paralysis
148. A patient is diagnosed with a form of motor neuron disease that initially affects neurons situated in the dorsolateral aspect of the ventral horn at L1 to L4. Which of the following arrangements best describes the deficit likely to be present?
a. LMN paralysis involving the hand
b. UMN paralysis of the upper limb
c. LMN paralysis of the back muscles
d. LMN paralysis of the leg
e. UMN paralysis of the leg
149. A small vascular lesion that affects the region of the ventromedial white matter of the cervical cord is discovered in a middle-aged man during a neurological examination. The neurologist came to the conclusion that the lesion affected the descending fibers of the medial longitudinal fasciculus (MLF). Which of the following deficits did the neurologist observe that led him to this conclusion?
a. The patient presented with a UMN paralysis.
b. The patient displayed difficulties in regulating his head position in response to postural changes.
c. The patient displayed an LMN paralysis.
d. The patient displayed ataxia of movement, nystagmus, and diplopia.
e. The patient experienced significant difficulties in regulating blood pressure and bladder functions.
150. A 26-year-old woman complains of some loss of sensation on both sides of her body, which seems to be localized around the region of her waist. A neurological examination reveals that the primary sensations lost are pain and temperature, although some bilateral loss of light touch is also noted. Which of the following is the most likely locus of the lesion?
a. Dorsal funiculus on both sides
b. Dorsal root ganglion, bilaterally
c. Region surrounding the central canal
d. Midline region of the lower medulla
e. Region of the ventral horn, bilaterally
151. An 18-year-old man is shot in the back and is taken to the emergency room. A neurological examination reveals that there is a hemisection of the right half of the spinal cord, extending from T8 to T12. Which of the following deficits will most likely result from this injury?
a. Loss of pain and temperature sensation from the right leg; loss of conscious proprioception from the left leg; UMN paralysis of the left leg
b. Loss of pain and temperature sensation from the left leg; loss of conscious pro-prioception from the right leg; UMN paralysis of the left leg
c. Loss of pain and temperature sensation from the left arm and leg; loss of conscious proprioception from the right leg and arm; flaccid paralysis of the right leg
d. Loss of pain and temperature sensation from the left leg; loss of conscious pro-prioception from the right leg; UMN paralysis of the right leg
e. Bilateral loss of pain and temperature sensation and conscious proprioception from the lower half of the body; UMN paralysis of the left leg; flaccid paralysis of the right leg
152. A 45-year-old woman is brought to her local hospital’s emergency room after experiencing several days of progressive weakness and numbness in her arms and legs. Her symptoms began with tingling in her toes, which she assumed to be her feet “falling asleep.” However, this feeling did not disappear. The numbness that first occurred in the toes of both feet subsequently ascended to her calves and knees. Two days later, she began to feel numbness in her fingertips and had difficulty lifting her legs. She was unable to climb the stairs of her house because of the weakness of her legs; she also had difficulty gripping the banister and experienced shortness of breath. At this stage, her husband urged her to go to the emergency room. The neurologist notes that she is short of breath while sitting on the bed. Her vital capacity (the greatest volume of air that can be exhaled from the lungs after a maximal inspiration) is far lower than would be expected for her age and weight. Her arms and legs are very weak, and she has difficulty lifting them against gravity. She is unable to feel a pin or a vibrating tuning fork on her legs or below her elbows but is able to feel the pin on her upper chest. The neurologist could not elicit any reflexes at her ankles or knees. A significant lesion is suspected. Where in the nervous system is the lesion most likely to be found?
a. Frontal lobe
b. Temporal lobe
c. Peripheral nerves and nerve roots
d. Spinal cord
e. Parietal lobe
153. In testing for the presence or absence of sensory functions, a neurologist administers a number of tests to a patient. One of them involves pinpricks placed in certain locations on different parts of the body. Which receptor is activated following such stimulation?
a. Merkel tactile disk
b. Ruffini corpuscle
c. Pacinian corpuscle
d. Free nerve endings
e. Meissner corpuscle
154. A 35-year-old man, who had his leg partially crushed in an industrial accident, is examined by a neurologist. The patient reports loss of sensory functions. The neurologist uses a tuning fork as one of the tools to test sensory function. If sensory processes were functioning properly, which receptor would be activated by the application of the vibrating tuning fork to different parts of the affected leg?
a. Free nerve endings
b. Muscle spindles
c. Pacinian corpuscle
d. Golgi tendon organ
e. Meissner corpuscle
155. A 55-year-old patient is involved in a severe motor vehicle accident and admitted to the emergency room. The patient complains of abnormal sensations of burning and tingling in the left arm. A neurological examination reveals little change in other sensory or motor functions. Which of the following regions was most likely affected by the accident?
a. Dorsal horn of the spinal cord
b. Ventral horn of the spinal cord
c. Ascending pathways in the lateral funiculus of the left spinal cord
d. Dorsal columns of the spinal cord
e. Nerve roots associated with the cervical cord
156. A 45-year-old man is involved in an industrial accident and develops complete flaccid paralysis and loss of sensation of the lower limbs. After a week, the patient regains movement of the limbs but experiences pain in the lower limbs, coupled with bladder dysfunction. All of these defects are most likely the result of which of the following?
a. Compression of the dorsal roots at L2
b. Compression of the entire spinal cord at L2
c. Compression of the dorsal columns at L2
d. Compression of the lateral funiculus at L2
e. A lesion transecting the corticospinal tracts at T1
157. A 35-year-old man, who has been in good health, notices that his right leg was weak. As the day progresses, he finds that he is dragging the leg behind him when he walks and finally asks a friend to drive him home from work because he is unable to lift his right foot up enough to place it on the gas pedal. He also notices that his left leg feels a little bit numb. His wife convinces him to go to the emergency room of the local hospital.
In the emergency room, he displays a great deal of difficulty in walking. He informs the physician that the weakness had started slowly several days before but he had ignored the symptoms. His language function, cranial nerves, and the motor and sensory examinations of his arms are within normal limits. When the physician examines his right leg, it is markedly weak, with very brisk reflexes in the knee and ankle. Vibration and position sense in the right leg are absent. Pain and temperature testing are normal in the right leg, but these sensations are absent on the left leg and abdomen up to the level of his umbilicus. Reflexes in the left leg are normal, but when the physician scratches the lateral portion of the plantar surface on the bottom side of his right foot, the great toe moves up. The remainder of the patient’s examination is normal. Which of the following is the primary site of the lesion?
a. Lower brainstem
b. Cervical spinal cord
c. Thoracic spinal cord
d. Lumbar spinal cord
e. Peripheral nerves
158. As a result of a hemisection of the spinal cord, a patient has loss of vibration and position sense in the right leg. Which of the following pathways has been affected by the lesion?
a. Right fasciculus cuneatus
b. Right fasciculus gracilis
c. Left fasciculus cuneatus
d. Left fasciculus gracilis
e. Right Lissauer tract
159. Following hemisection of the spinal cord, approximately at the level of T3, a patient experiences loss of pain and temperature sensation on the left side of the leg. Damage to which of the following tracts by the hemisection could account for this deficit?
a. Right fasciculus cuneatus
b. Right fasciculus gracilis
c. Right spinothalamic tract
d. Left spinothalamic tract
e. Left corticospinal tract
160. After a hemisection of the spinal cord at T3, a patient experiences marked weakness in the right leg. Which of the following best accounts for this weakness?
a. There was muscle damage in the right leg
b. There was damage in his left frontal lobe
c. There was damage to the right corticospinal tract
d. The dorsal root was damaged
e. There was damage to the right femoral nerve
161. In testing for motor dysfunctions, a neurologist identifies an upward movement of the patient’s toe when the plantar surface of his foot is scratched. This response is indicative of a lesion of a part of the nervous system. Which of the following is linked to this response?
a. UMNs
b. LMNs
c. Peripheral nerves
d. Skeletal muscles
e. Autonomic nerves
162. A neurologist observes weakness in distal hand muscles and arm, as well as spasticity, upon testing for motor functions in a patient. The neurologist is most likely to believe that the defect is due to damage of which of the following?
a. Ventral horn of spinal cord
b. Ventral roots
c. Cerebral cortex
d. Dorsal root ganglia
e. Ulnar, posterior cutaneous, and median nerves
163. A neurological examination reveals a significant loss of the knee jerk reflex involving the quadriceps muscle. It is further determined that the defect is due to a constriction of the nerve, approximately at the level of the nerve root. The root involved in this defect is which of the following?
a. S1 to S2
b. S3
c. L3 to L4
d. L1
e. T12
164. A 65-year-old man is admitted to a local hospital following an assault and is examined by a team of physicians that includes a neurologist. After several days, the patient has motor deficits involving the right arm and right leg—the right arm shows no movement while the right leg displays a spastic paralysis. In addition, there is loss of pain sensation on the lower left side of the body, along with loss of vibration and position sense on the upper part of the right side of the body. It is determined that the knife wound that the patient had sustained has damaged which one of the following areas?
a. Left cervical spinal cord
b. Left thoracic spinal cord
c. Right cervical spinal cord
d. Right lumbar spinal cord
e. Right ventromedial medulla
165. A patient is admitted to a hospital after his internist observed the following symptoms: abrupt paralysis of the lower limbs, sphincter paralysis, and related autonomic problems as well as segmental loss of pain temperature, without loss of conscious proprioception of either the legs or arms. It was concluded that the patient suffers from which of the following?
a. A tumor causing compression of neural tissue at the spinal cord-medulla junction
b. Occlusion of the vertebral artery
c. Occlusion of the posterior spinal artery
d. Occlusion of the anterior spinal artery
e. A tumor proximal to the central canal of the spinal cord
166. A 68-year-old man complains of severe pain in his lower leg. Following examination, it is concluded that the pain is limited to the posterolateral aspect of the lower extremity. There is loss of plantar flexion of the foot and of the ankle reflex of the affected limb. The test for dorsiflexion of the foot is normal. These findings suggest a lesion of which of the following?
a. Ventral half of the sacral spinal cord
b. Ventral horn cells of the lumbar spinal cord
c. Sciatic nerve
d. Deep peroneal nerve
e. S1 nerve root
167. A 47-year-old woman complains of weakness of her wrist. Examination reveals weakness of the wrist and of the extensor muscles of the forearm, with normal function in the other muscles. These deficits suggest a lesion of which of the following?
a. Primary motor cortex
b. Premotor cortex
c. Medullary reticular formation
d. Ventral horn of cervical spinal cord
e. Radial nerve
168. A 23-year-old professional football player was going through a series of exercises prior to a preseason game which involve stretching of his shoulder and upper arm, and inadvertent twisting of his neck. He soon experiences severe pain in the shoulder and upper arm, weakness of the arm muscles, and some sensory loss. A neurological examination reveals that several reflexes are impaired. Which of the following is the primary site of the lesion?
a. Cranial nerve XI
b. Nerve root at C1
c. The brachial plexus
d. Radial nerve
e. Ulnar nerve
169. A 61-year-old man was admitted to a local hospital after complaining of disturbances of urination; loss of sexual function; and sensory abnormality, which included complete saddle anesthesia. A neurological examination led the neurologist to conclude that there was a lesion of one of the following regions?
a. Medial aspect of the premotor cortex
b. Medullary pyramids
c. Lateral funiculus of spinal cord at L2
d. Conus medullaris of spinal cord
e. Spinal root at L5
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