These neurological signs are characteristic of a lesion in the structure indicated by which arrow in Fig. 1-17?

A30-year-old patient displays ataxia of extremities and asynergy with decomposition of movement. He also has dysmetria (past-pointing phenomenon), dysdiadochokinesia (the inability to perform rapidly alternating movements), and intention tremor. These neurological signs are characteristic of a lesion in the structure indicated by which arrow in Fig. 1-17?

(A) 1
(B) 2
© 3
(D) 4
(E) 5

explanation

(D)The collective neurological signs are characteristic of a lesion of the neocerebellum (cerebellar hemispheres). Alesion in the archicerebellum (cerebellar vermis; arrow 5, choice E) results in loss of equilibrium. None of the other choices
apply to the collection of neurological signs displayed by this patient: arrow 1 (choice A) points to the temporal lobe, arrow 2 (choice B) to the eyeball, and arrow 3 (choice C) to the pons.