Anatomy of the Cerebellum

Location and Relations

• The cerebellum occupies the posterior cranial fossa, related anteriorly by the pons, medulla oblongata (MO), and 4th ventricle, superiorly by the tentorium cerebelli and occipitotemporal cortex, and posteroinferiorly by the squamous part of the occiput.

Surfaces

• The superior surface is convexoconcave in conformity with the shape of the tentorium.
• The postinferior surface is convex backwards in conformity with the shape of the occiput and contains the postcerebellar notch that lodges the falx cerebelli, partially separating the two cerebellar hemispheres.
• The anteroinferior surface is flat and contains the anterior cerebellar notch, which is wide and shallow and lodges the pons and MO, separated from them by the 4th ventricle.

Major Parts

• The cerebellum consists of two cerebellar hemispheres joined at the midline in a constricted "worm-like" portion called the vermis, which is divided into superior and inferior parts.
• The anteroinferior parts of the cerebral hemispheres expand into spherical parts called cerebellar tonsils.

Cerebellar Nuclei

• Interposed nuclei are present in the cerebellum.

Functional Zones

• The cerebellum has functional zones that are not specified in the text.

Fissures and Lobes

• A primary fissure runs horizontally on the superior surface and separates the anterior from the posterior lobes.
• The part of the vermis ventral to the primary fissure is the superior vermis, and the part dorsal to the fissure is the inferior vermis.
• A horizontal fissure runs horizontally in the posterior lobe and separates the superior from the posterior surfaces.
• A postrolateral fissure separates the posterior lobe from the flocculonodular lobe on the anteroinferior surface.

Connections

• The cerebellum controls the ipsilateral side of the body.
• Spinocerebellar afferents include ventral spinocerebellar (double-crosser), dorsal spinocerebellar (uncrossed), and cuneocerebellar (uncrossed) afferents.
• Cerebral afferents are crossed, and vestibulovisual afferents are uncrossed.
• Cerebellar efferents are not specified in the text.

Clinical Relevance

• Cerebellar signs include dysdiadochokinesia (inability to perform rapid repetitive movements), ataxia (unbalanced gait/limb movement/swallowing), nystagmus (involuntary rhythmic eye movements), intention tremor (muscular tremor brought on by movement and absent during rest), hypotonia (floppy limbs/muscles), and dysmetria (past-pointing, inability to estimate range and distance).