Anatomy of cerebellum and its most important connections

1. Big picture

The cerebellum is the major coordination center of the nervous system. It does not initiate movement like the motor cortex; instead, it compares the intended movement with the actual movement and corrects errors in timing, force, range, posture, balance, eye movements, and speech coordination.

For the exam, the most important idea is this:

A cerebellar hemisphere coordinates the ipsilateral side of the body. Therefore, a right cerebellar lesion gives right-sided limb ataxia, dysmetria, dysdiadochokinesia, hypotonia, and intention tremor.

This is a classic exam trap because most corticospinal and sensory pathways cross, but cerebellar signs are usually ipsilateral.