الفهرس 
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Abstract
The cerebellum is located behind the dorsal aspect of the pons and the medulla. It is separated from the occipital lobe by the tentorium and fills most of the posterior fossa. A midline portion, the vermis, separates two lateral lobes, or cerebellar hemispheres. The external surface of the cerebellum displays a large number of narrow, ridge-like folds termed folia ,most of which are oriented transversely. . Because of the location of the fourth ventricle, ventral to the cerebellum, mass lesions or swelling of the cerebellum can cause obstructive hydrocephalus. The cerebellum is divided into two symmetric hemispheres; they are connected by the vermis, Three pairs of peduncles, located above and around the fourth ventricle, attach the cerebellum to the brain stem and contain pathways to and from the brain stem. These are the superior, middle and inferior cerebellar peduncles. The cerebellum is responsible for coordinating muscle groups and controlling small movements and balance.(2,3) (see Fig 7)