chapter 15 Flashcards
1. A 30-year-old woman complains of unsteadiness while standing or walking. She tends to deviate to the right. Neurologic examination reveals the following signs: dysmetria on the right, dysdiadochokinesia, and a nystagmus that is more marked when she looks to the right side. The lesion is most likely found in the (A) cerebellar hemisphere, left side (B) cerebellar hemisphere, right side (C) medial medulla, left side (D) medial medulla, right side (E) globus pallidus, left side
l-B.
Dysmetria, dysdiachokinesia, intention tremor, and nystagmus are classic cerebellar signs. In the finger-to-nose test, the patient past-points on the side of the lesion. The medial medulla has no cerebellar pathways. In contrast, the lateral medulla has cerebellar pathways; lesions result in cerebellar ataxia and could be misdiagnosed as a cerebellar hemispheric lesion. The globus pallidus, a basal ganglion, is atrophied in Huntington disease and in Wilson disease, and it is damaged bilaterally by carbon monoxide intoxication.
2. Purkinje cells of the cerebellum project inhibitory axons to which of the following nuclei? (A) Fastigial nucleus (B) Superior olivary nucleus (C) Inferior olivary nucleus (D) Arcuate nucleus (E) Ventral lateral nucleus
2-A.
Purkinje cells project inhibitory axons to all cerebellar nuclei: fastigial, globose, emboliform, and dentate. In addition, they project to all vestibular nuclei: lateral, superior, medial, and inferior. The superior olivary nucleus is an auditory relay nucleus, and the inferior olivary nucleus is a cerebellar relay nucleus. The arcuate nucleus is an ectopic pontine nucleus that lies next to the pyramidal tract; its function is unknown. The ventral lateral thalamic nucleus receives input from the dentate nucleus.
3. The most common cause of the anterior vermis syndrome is (A) alcohol abuse (B) an abscess (C) a tumor (D) vascular occlusion (E) lead intoxication
3-A.
Anterior vermis syndrome is a result of chronic alcohol abuse. Patients present with dystaxia of the lower limb and trunk. Posterior vermis syndrome involves the flocculonodular lobe; it is most frequently caused by an ependymoma or a medulloblastoma. Patients have truncal dystaxia. Hemispheric syndrome usually is the result of a tumor (astrocytoma) or abscess; patients have arm, leg, trunk, and gait dystaxia
4. The most common cerebellar tumor in children is (A) astrocytoma (B) ependymoma (C) glioblastoma multiforme (D) oligodendrocytoma (E) medulloblastoma
4-A.
Astrocytomas (30%) are the most common cerebellar tumors in children; they are followed by medulloblastomas (20%) and ependymomas (10%).
5. A tumor that is derived from the external granular layer of the cerebellar cortex is an (A) astrocytoma (B) chordoma (C) ependymoma (D) germinoma (E) medulloblastoma
5-E.
Medulloblastomas are derived from the external granular layer of the cerebellar cortex. Medulloblastomas give rise to posterior vermis syndrome.
6. The inferior cerebellar peduncle contains all of the following afferent connections EXCEPT the (A) cuneocerebellar tract (B) ventral spinocerebellar tract (C) dorsal spinocerebellar tract (D) olivocerebellar tract (E) trigeminocerebellar fibers
6-B.
The ventral spinocerebellar tract enters the cerebellum via the superior cerebellar peduncle.
- All of the following statements concerning the superior cerebellar peduncle are correct EXCEPT
(A) it connects the cerebellum to the midbrain
(B) it is primarily an efferent bundle of fibers
(C) it represents the major output from the
cerebellum
(D) it contains dentatothalamic fibers
(E) it contains the juxtarestiform body
7-E.
The inferior cerebellar peduncle includes the restiform body and the juxtarestiform body.
The juxtarestiform body contains vestibulocerebellar, cerebellovestibular, and cerebelloreticular fibers.
- All of the following statements concerning the vestibulocerebellar pathway are correct EXCEPT
(A) it plays a role in the initiation, planning, and timing of voluntary motor activities
(B) it projects via the medial longitudinal fasciculus (MLF)
(C) it receives input from the cristae ampullares
(D) it receives input from the maculae of the utricle and saccule
(E) it includes the flocculonodular lobe
8-A.
The vestibulocerebellum (archicerebellum) plays a role in the maintenance of posture and
balance and in the coordination of head and eye movements.
- All of the following statements concerning the red nucleus are correct EXCEPT
(A) it influences the cerebellum via the inferior olivary nucleus
(B) its primary effect is on truncal and proximal muscles
(C) it receives bilateral input from the motor and premotor cortex
(D) it receives contralateral input from the
nucleus interpositus
(E) it receives modest input from the con-
tralateral dentate nucleus
9-B.
The red nucleus gives rise to the crossed rubrospinal tract, which has its primary effect on distal muscle groups. The red nucleus is a way station in the paravermal spinocerebellar pathway, a system dedicated to distal motor control and ongoing execution of motor acts.
- All of the following statements concerning the neocerebellar pathway are correct EXCEPT
(A) the neocerebellar pathway influences the motor cortex via the ventral anterior thalamic nucleus
(B) the dentatothalamic tract decussates in the midbrain
(C) the corticopontocerebellar tract decussates in the base of the pons
(D) the neocerebellum expresses itself via the corticospinal tract
(E) the dentate nucleus is reciprocally connected with the inferior olivary nucleus
10-A.
In the neocerebellar pathway, the dentate nucleus projects to the contralateral ventral lateral nucleus of the thalamus, which in turn projects to the motor cortex. The motor cortex gives rise to the crossed corticopontocerebellar tract, which then modifies further cerebellar output to the neocortex, as well as to the corticospinal and corticobulbar tracts. The neocerebellum thus expresses itself via the corticospinal (pyramidal) and corticobulbar (corticonuclear) tracts
11. Signs of cerebellar dysfunction include all of the following EXCEPT (A) hypotonia (B) slurred or scanning speech (C) resting static pill-rolling tremor (D) dysdiadochokinesia (E) decomposition of movement
11-C. Cerebellar signs include hypotonia, disequilibrium, muscle incoordination (dyssynergia), and nystagmus. Intention tremor is a variation of dysmetria (inability to estimate distances correctly) and is commonly seen in lesions of the cerebellar hemispheres or their central projections.
Dysdiadochokinesia is the inability to perform rapid alternating movements. Decomposition of movement is a breakdown of smooth muscular movement into a number of component steps. A resting static pill-rolling tremor is seen in Parkinson disease.
- All of the following statements concerning cerebellar nuclei are correct EXCEPT
(A) the fastigial nucleus projects to the thalamus
(B) the fastigial nucleus projects to the brainstem via the superior and inferior cere-
bellar peduncles
(C) the fastigial nucleus and the emboliform nucleus are called the interposed nucleus
(D) the dentate nucleus produces the bulk of the axons found in the superior cerebellar
peduncle
(E) Purkinje cells project to all of the cerebellar nuclei
12-C.
The emboliform and globose nuclei are called the interposed nucleus. The fastigial nucleus projects to the vestibular nuclei via the uncinate fasciculus (a component of the superior cerebellar peduncle) and via the juxtarestiform body (a component of the inferior cerebellar peduncle). The dentate nucleus, the largest of the cerebellar nuclei, gives rise to the bulk of the axons in the superior cerebellar peduncle.
- All of the following statements concerning the cerebellum are correct EXCEPT
(A) it contains four pairs of nuclei within its medullary body
(B) it contains two pairs of cerebellar peduncles
(C) it consists of a midline vermis and two
lateral hemispheres
(D) it is located infratentorially within the
posterior fossa
(E) it has a three-layered cortex
13-B.
The cerebellum is attached to the brainstem by three pairs of cerebellar peduncles: Superior cerebellar peduncles connect to the pons and midbrain; middle cerebellar peduncles connect to the pons; and inferior cerebellar peduncles attach to the medulla.
- All of the following statements concerning the cerebellum are correct EXCEPT
(A) it projects to the red nucleus
(B) it projects to the vestibular nuclei
(C) it projects to the lateral ventral nucleus of the thalamus
(D) it receives input from the superior olivary nucleus
(E) it receives the olivocerebellar tract via the inferior cerebellar peduncle
14-D.
The superior olivary nucleus is a relay nucleus of the auditory system and does not project to the cerebellum. The inferior olivary nucleus of the medulla projects to the cerebellum via the inferior cerebellar peduncle.
15. All of the following statements concerning the cerebellum are correct EXCEPT (A) it is derived from the alar plate (B) it develops from the rhombic lips (C) it is part of the metencephalon (D) it is part of the rhombencephalon (E) it is part of the brainstem
15-E.
The cerebellum develops from the rhombic lips of the alar plates. The metencephalon (afterbrain) consists of the pons and cerebellum, and the rhombencephalon (hindbrain) includes the metencephalon and the myelencephalon (medulla oblongata). The brainstem (truncus cerebri) includes the midbrain, pons, and medulla oblongata; some authorities also include the diencephalon.
