cerebelli

The cerebelli are, in anatomical terms, the cerebellum. In English usage the singular cerebellum is standard, while cerebelli is the Latin plural form and may appear in academic phrases or veterinary contexts referring to multiple cerebellums. In a single human brain, the organ is a single structure with two hemispheres.

Anatomy and structure: The cerebellum lies in the posterior cranial fossa, beneath the occipital lobes and behind the brainstem. It consists of two cerebellar hemispheres connected by the midline vermis and is traditionally divided into the anterior, posterior, and flocculonodular lobes. The outer gray matter forms a highly folded cortex (folia) over a white matter skeleton. Deep within are the cerebellar nuclei: dentate, interposed (emboliform and globose), and fastigial, which relay processed information to other brain regions.

Connections and function: Afferent inputs arrive from the spinal cord, brainstem, vestibular system, and cerebral cortex (via pontine nuclei). Efferent outputs travel from the deep nuclei to the thalamus and brainstem, modulating motor commands. The cerebellum coordinates movement, maintains posture and balance, and supports motor learning and the precise timing of actions. It also contributes to cognitive and affective processing through cerebrocerebellar circuits.

Clinical significance: Lesions can cause ataxia, dysmetria, intention tremor, nystagmus, and gait instability. Causes include stroke, tumors, degenerative diseases, and trauma. Diagnosis often relies on MRI or CT imaging, and management focuses on treating the underlying cause and performing rehabilitation to improve coordination and balance.

Evolution and development: The cerebellum is a conserved hindbrain structure across vertebrates. It develops from the embryonic rhombic lip and expands variably among species, reflecting demands on motor coordination and learning.