The purpose of testing cerebellar function is to look for evidence of a lesion involving the cerebellum or the cerebellar pathways.

Cerebellar function should be examined in all patients as part of a standard neurologic examination. This should include the finger-to-nose maneuver (see Chapter 34, Testing of Upper Extremity Cerebellar Function) and observation of gait (see Chapter 39, Examination of Gait). Other tests of cerebellar function, such as rapid alternating movements or testing for rebound, should be performed when there is a clinical suspicion for a cerebellar abnormality and are discussed in Chapter 34, Testing of Upper Extremity Cerebellar Function, and Chapter 35, Testing of Lower Extremity Cerebellar Function.

The function of the cerebellum is to coordinate movements. The midline of the cerebellum (the vermis) is primarily involved in truncal balance and gait. The lateral parts of the cerebellum (the two cerebellar hemispheres) coordinate the movements of the ipsilateral extremities. In other words, the left cerebellar hemisphere coordinates the left arm and leg, and the right cerebellar hemisphere coordinates the right arm and leg.

There are also pathways to and from the cerebellum that travel through the cerebral hemispheres and the brainstem; these cerebellar pathways in the internal capsule and the base of the pons coordinate the contralateral extremities. In other words, the cerebellar-destined fibers located within the left internal capsule or left pons are involved in coordination of the right arm and right leg.

None.

Examination of upper extremity cerebellar function, including testing finger-to-nose, rapid alternating movements, and rebound, is described in Chapter 34
, Testing of Upper Extremity Cerebellar Function. Examination of lower extremity cerebellar function, including heel-to-shin testing, is described in Chapter 35, Testing of Lower Extremity Cerebellar Function. The examination of gait and tandem gait is described in Chapter 39, Examination of Gait.