Chapter 13: The Cerebellum
A person has a tumor in the posterior fossa, on the dorsal surface of the cerebellum. Which of the following statements best describes the location of the tumor?
A. Between the cerebellum and the occipital lobe
B. Between the cerebellum and medulla
C. Between the cerebellum and temporal lobe
D. Between the cerebellum and tentorium
Comment: The tentorium separates the cerebellum from the overlying occipital and temporal lobes. Because of this, the tumor does not contact either lobe.
From lateral to medial, the anterior and posterior lobes of the cerebellar cortex connect with the deep nuclei in the following order:
A. dentate, interposed, fastigial
B. fastigial, interposed, dentate
C. dentate, fastigial, vestibular
D. fastigial, interposed, dentate, vestibular
Which of the following is the principal synaptic target of Purkinje cells of the nodulus?
A person had a unilateral cerebellar stroke. Which of the following best explains the laterality (ie, side of body on which ataxia presents) of ataxia during reaching?
A. Contralateral, because cerebellar output is not decussated and the descending motor pathways are crossed
B. Ipsilateral, because cerebellar output decussates and the descending pathways cross
C. Bilateral, because the cerebellar output decussates and the descending pathways cross
D. Bilateral, because the descending pathways are bilateral
Comment: Limb motor signs are classically ipsilateral to cerebellar lesions. This is because the circuit is double crossed—once as the output of the cerebellum, and the second as the decussation of the motor pathway. The principal input paths to the cerebellum, the dorsal and cuneocerebellar tracts, are ipsilateral.
Which of the following circuits traces the connection, via the cerebellum, from the right posterior parietal cortex to the spinal cord?
A. Triple crossed: right posterior parietal cortex→right pons→left cerebellum→right thalamus→right motor cortex→left spinal cord
B. Double crossed: right posterior parietal cortex→right pons→right cerebellum→left thalamus→left motor cortex→right spinal cord