Examenvragen - Neuroanatomy
The most likely region affected by the stroke that could account for limb paralysis is:
a. Prefrontal cortex
b. Precentral gyrus
c. Postcentral gyrus
d. Superior temporal gyrus
e. Parietal lobe
Answer: b
The primary motor cortex is located in the precentral gyrus, which is organized somatotopically. The functions of
the upper and lower limbs are represented in different regions along the precentral gyrus. The postcentral gyrus
represents a primary somesthetic receiving area for pain, temperature, pressure, kinesthetic, and tactile impulses
from the periphery. Although the superior frontal gyrus contains certain groups of neurons (the supplementary and
premotor motor areas) that also contribute to motor functions, it is not a primary motor area. The superior parietal
lobule is associated with sensory discrimination processes and with the programming of signals to the premotor
cortex. The posterior parietal cortex represents a region of sensorimotor integration and the organization of
complex response patterns.
The loss of speech in this patient was due mainly to damage of the:
a. Superior frontal cortex
b. Inferior temporal gyrus
c. Inferior frontal gyrus
d. Occipital cortex
e. Medial aspect of parietal cortex
Answer: c
The posterior aspect of the inferior frontal gyrus contains a region called “Broca’s motor speech” area. Lesions
affecting this region produce motor aphasia, which is characterized by a loss of ability to express thoughts in a
meaningful manner. The superior aspect of the frontal cortex is associated with movements of the lower limbs, the
inferior temporal gyrus is associated with perceptual functions, the occipital cortex is associated with vision, and
the medial aspect of the parietal lobe is associated with somatosensory functions involving the leg.
During routine surgery for appendicitis, a clot is released from the lung of a 75-year-old man, causing the patient to
remain unconscious for a period of 1 week. Upon regaining consciousness, the patient finds that he is unable to
maintain his balance and, further, displays tremors while attempting to produce a purposeful movement. In addition, the
patient’s movements are not smooth but jerky and lack coordination. The region affected most likely include the:
a. Spinal cord
b. Medulla
c. Pons
d. Midbrain
e. Cerebellum
Answer: e
Although the spinal cord, medulla, pons, and midbrain play important roles in motor functions, the primary functions of
the cerebellum include regulation of motor functions. Damage to parts of this structure causes a loss of balance, loss
of coordination of movements, and tremors. Unlike the cerebellum, none of the other regions has a direct role in the
regulation of these processes.
A magnetic resonance image scan taken of a 60-year-old woman revealed the presence of a tumor on the base of the
brain that was situated just anterior to the pituitary and that impinged upon the adjoining neural tissue. A likely deficit
resulting from this tumor includes:
a. Loss of movement of upper limbs
b. Speech impairment
c. Difficulties in breathing
d. Changes in emotionality
e. Loss of ability to experience pain
Answer: d
The optic nerve enters the brain at the level of the far anterior hypothalamus. Tumors of this region of the base of the
brain commonly affect the hypothalamus, which plays an important role in the regulation of emotional behavior and
autonomic functions. Such tumors would also likely affect visual functions. Movements of the limbs are affected by
lesions of the internal capsule or precentral gyrus; speech impairment is affected by damage to the inferior frontal or
superior temporal gyrus; breathing is affected by the lower brainstem; and pain is affected by parts of the brainstem,
thalamus, and postcentral gyrus.
,A 45-year-old man complained about having recurring headaches over a period of weeks. Subsequent tests revealed the
presence of a tumor along the lateral wall of the anterior horn of the lateral ventricle, which did not produce hydrocephalus.
One region that would be directly affected by the tumor is the:
a. Caudate nucleus
b. Putamen
c. Globus pallidus
d. Hippocampus
e. Cingulate gyrus
Answer: a
The head of the caudate nucleus is located adjacent to the lateral aspect of the anterior horn of the lateral ventricle.
Therefore, a tumor in this region would include the head of the caudate nucleus. The putamen and globus pallidus lie
lateral to the caudate nucleus at a position away from the lateral ventricle, the hippocampus lies adjacent to the inferior
horn of the lateral ventricle, and the cingulate gyrus lies above the corpus callosum in a position not in proximity to the
lateral ventricle
A 22-year-old man was admitted to the emergency room after a motorcycle accident. A clinical examination showed that
he had elevated intracranial pressure (ICP) due to head trauma. The patient suffered from severe bradycardia. Acting on
which of the following brain regions would elevated ICP most likely cause bradycardia?
a. Cerebral cortex
b. Basal ganglia
c. Brainstem
d. Thalamus
e. Cerebellum
Answer: c
The craniovertebral cavity and its dural lining form a closed space. An increase in the size or volume of any
constituent of the cranial cavity results in an increase in intracranial pressure (ICP). The following symptoms may
accompany increased ICP: loss of consciousness, headache, nausea and vomiting, increase in systemic blood
pressure, and bradycardia. The bradycardia (decrease in heart rate) is usually due to the increased pressure on the
nucleus ambiguus and dorsal motor nucleus of vagus located in the medulla. The other brain structures listed are not
involved in the control of heart rate.
The membranes that line the cisterns in the cranial cavity are:
a. Dura and arachnoid mater
b. Dura mater and ependymal cell layer
c. Neuronal cell membrane and the pia mater
d. Pia and arachnoid mater
e. Periosteal and meningeal layers of dura mater
Answer: d
The cisterns are formed by enlargements of subarachnoid space located between the pia and arachnoid mater. Other
choices listed are not appropriate. For example, there is no space between the dura and arachnoid mater. Ependymal
cells line the ventricles. There is no space between the pia and brain tissue; the pia mater is tightly attached to the
brain. The periosteal and meningeal layers of the dura mater are fused except at the places where venous sinuses
are located.
Which of the following statements is correct regarding a graded potential?
a. It has a threshold.
b. Its amplitude varies with the intensity of the stimulus.
c. It has a long refractory period.
d. It has a constant duration.
e. It is mediated via a voltage-gated ion channel.
Answer: b
The amplitude of a graded potential varies with the intensity of the stimulus; the response is graded. It has no
threshold or refractory period. Its duration depends on the initial stimulus. It is mediated by a receptor (not voltage-
gated ion channel).
, The neurologic examination of a 60-year-old man revealed that he is suffering from Parkinson’s disease. Which one of
the following statements is true concerning this disease?
a. It involves a degeneration of cholinergic neurons in the basal nucleus of Meynert.
b. It involves a degeneration of noradrenergic neurons of the locus ceruleus.
c. It involves a degeneration of dopaminergic neurons of the substantia nigra.
d. Oral administration of dopamine is likely to relieve the symptoms of Parkinson’s disease.
e. It is usually associated with hyperkinetic syndrome.
Answer: c
Parkinson’s disease is characterized by tremor at rest, slowness of movement (bradykinesia or hypokinetic
syndrome), rigidity of extremities and neck, and an expressionless face. Dopaminergic neurons located in the
substantia nigra are degenerated in this disease, and the release of dopamine in the caudate nucleus and putamen is
decreased. Drug treatment of this disease is aimed at replacement of the deficiency of the transmitter (dopamine) in
the basal ganglia (target of nigrostriatal projection). Because dopamine does not cross the bloodbrain barrier, its
immediate metabolic precursor (levodopa or L-DOPA), which does cross this barrier, is administered orally. L-DOPA
is transported into the brain via a large neutral amino acid transporter, and it permeates the striatal tissue where it is
decarboxylated to dopamine. The levels of DOPA in the plasma are increased by simultaneous administration of
carbidopa and L-DOPA. Carbidopa inhibits dopa-decarboxylase, which converts DOPA into dopamine. Carbidopa
does not cross the blood-brain barrier.
A neuropathologist received a brain specimen from a deceased Alzheimer’s patient for postmortem histological
examination. Which one of the following neuronal groups is likely to be degenerated in this specimen?
a. Basal nucleus of Meynert
b. Raphe magnus
c. Locus ceruleus
d. Nucleus ambiguus
e. Substantia nigra
Answer: a
In Alzheimer’s patients, there is a dramatic loss of cholinergic neurons in the basal nucleus of Meynert. The other
nuclei mentioned are not implicated in this disease. The raphe magnus, locus ceruleus, and nucleus ambiguus are
concerned with descending control of pain sensation, forebrain activity during sleep and wakefulness cycles, and
heart rate regulation, respectively. Dopaminergic neurons in the substantia nigra are degenerated in Parkinson’s
disease.
A 27-year-old man was involved in a street brawl, and during the fight, he was stabbed in the back. He lost con-
sciousness and was rushed to the emergency room of a local hospital. After regaining consciousness, the patient
received a neurologic examination. The patient indicated to the neurologist that he could not feel any pricks of a safety
pin when tested along a band of an approximately 4-cm ring, which included both sides of his back. The patient was able
to recognize tactile stimulation when tested on his arms and legs of both sides of the body as well as on the back or
chest. Motor functions appeared to be intact. The neurologist concluded that the patient suffered damage of the:
a. Substantia gelatinosa
b. Dorsal root ganglion of the left side
c. Lateral funiculus of both the lumbar and thoracic cords of the left side
d. Region surrounding the central canal of thoracic cord
e. Dorsal columns at the level of thoracic cord, bilaterally
Answer: d
Bilateral segmental loss of pain is the result of damage to the region surrounding the central canal of the spinal cord.
This is due to damage to the crossing fibers of the lateral spinothalamic tracts (on each side) at a specific level of the
cord. Damage to the substantia gelatinosa or dorsal root ganglia could only account for unilateral loss of pain. Damage
to the lateral funiculus at both lumbar and thoracic levels on one side would likewise not account for bilateral loss of pain
and, additionally, such a lesion would not be segmental. Dorsal column lesions would not affect the pathways mediating
pain but, instead, would affect conscious proprioception
A security guard at a bank was shot in the back during an attempted bank robbery. He was admitted to the emergency
room, and when he regained consciousness, he was given a neurologic examination. The patient indicated that he could
not detect tactile stimulation of the left leg, although sensation in the left arm after similar stimulation was intact. When a
pinprick was applied to all four limbs, the patient said that he could not feel the sensation in his right leg, whereas this
sensation was present in his left leg and both arms. In addition, further neurologic examination indicated that the patient
could not move his left leg. The neurologist concluded that there was damage to the:
a. Dorsal horn of the right side of the thoracic cord
b. Region surrounding the central canal of the lumbar cord
c. Region of the dorsal columns, bilaterally
d. Ventral horn of the left side of the thoracic cord
e. Left half of lower thoracic cord
