Neuroscience: The Cerebellum Overview

The Cerebellum

• The cerebellum regulates voluntary movement and posture (balance and muscle tone) indirectly by adjusting the output of the major descending systems of the brain. This includes motor learning.
• Cerebellar lesions disrupt coordination of eye and limb movements, impair balance, and decrease muscle tone.
• The cerebellum comprises 10% of the brain's total volume but contains more than half of all the neurons.
• The cerebellum helps provide smooth, coordinated body movement.

Cerebellar Location and Relationships

• The cerebellum sits in the posterior cranial fossa, inferior to the occipital lobes.
• It is separated from the cerebrum by the tentorium cerebelli.
• Surrounding structures include the superior sagittal sinus, falx cerebri, occipital lobe, and tentorium cerebelli.
• The arachnoid mater also covers the medulla oblongata.
• The cerebellum lies on top of the medulla and pons.

Cerebellar Nuclei

• Deep cerebellar nuclei (dentate, emboliform, globose and fastigial) process sensory input and send motor output to other parts of the brain.
• The nuclei are involved in cerebellar function.
• These nuclei are situated within the cerebellum's white matter.

Cerebellar Afferents

• Sensory information enters the cerebellum from various sources.
• This information originates from the spinal cord (via the anterior and posterior spinocerebellar & cuneocerebellar tracts).
• The vestibular apparatus also sends information (vestibulocerebellar tract).
• A small amount of input directly enters from the cerebral cortex (motor, premotor, sensory, and posterior parietal cortex).
• Additional information travels via the corticopontocerebellar tract, tectocerebellar, rubrocerebellar, and reticulocerebellar tracts.

Cerebellar Efferents

• The cerebellum uses deep cerebellar nuclei (dentate, emboliform, globose, and fastigial) to send output.
• These nuclei relay signals to pathways controlling posture and movement.
• Vestibular nuclei are considered functionally part of the deep cerebellar nuclei.
• Pathways from the different nuclei adjust the descending motor pathways.
• Output is sent to red nuclei, vestibular nuclei, inferior olivary nuclei, and reticular nuclei, ultimately leading to spinal cord, and thalamus.

Cerebellar Arteries

• Blood supply to the cerebellum is from branches of the vertebrobasilar system.
• Posterior inferior cerebellar artery (PICA) is a branch of the vertebral artery.
• Anterior inferior cerebellar artery (AICA) is a branch of the basilar artery.
• Superior cerebellar artery (SCA) arises from the basilar artery.

Venous Drainage of the Cerebellum

• Superior cerebellar veins drain into the superior sagittal sinus.
• Inferior cerebellar veins drain into the transverse sinuses.
• Some veins enter the posterior spinal vein.

Cerebellar Function and Disorders

• The cerebellum plays a crucial role in motor control, balance, and coordination.
• Disorders can impact posture, muscle tone, movement, and reflexes.
• Specific cerebellar disorders, like ataxia, tremors, and nystagmus must be screened with tests (finger-nose tests, tandem gait, Romberg's tests, and diodochokinesis).

Explore the fascinating functions and anatomy of the cerebellum in this quiz. Learn about its role in movement regulation, coordination, and neuronal density. Understand its anatomical relationships with surrounding brain structures.