Cerebellum Overview and Structures

The Cerebellum

• The cerebellum is a part of the brain, located posterior to the brainstem.
• It plays a crucial role in coordinating movement, balance, and posture.
• It consists of three lobes: anterior, posterior, and flocculonodular.
• The anterior lobe is involved in fine motor control.
• The posterior lobe is associated with skilled movements.
• The flocculonodular lobe is connected to equilibrium and posture.
• The cerebellum receives input from various brain regions, including the cerebral cortex, brainstem, and spinal cord.
• It relays information back to these regions to refine and coordinate movement.

Cerebellar Structures

• Cerebellar peduncles: These are bundles of nerve fibers, connecting the cerebellum with the brainstem.
  • Superior cerebellar peduncle: Contains efferent fibers to the red nucleus and thalamus.
  • Middle cerebellar peduncle: The largest peduncle, made up of pontine fibers.
  • Inferior cerebellar peduncle: Links the cerebellum to the medulla and contains olivocerebellar and cerebellolivary fibers.

Cerebellar Surfaces and Fissures

• Superior surface: Shows the superior vermis. Fissura prima separates the anterior (2/3) and posterior/middle (1/3) lobes.
• Inferior surface: Shows the inferior vermis. Fissura secunda separates the uvula and pyramid.

Cerebellar Lobes

• Anterior lobe: Lies anterior to the primary fissure.
• Posterior lobe: Lies posterior to the primary fissure.
• Flocculonodular lobe: Located on the inferior surface and separated from the posterior lobe by the posterolateral fissure.

Cerebellar Notches

• Two notches: Anterior notch surrounds the brainstem.
• Posterior notch.

The 4th Ventricle

• The 4th ventricle is a part of the ventricular system.
• Its roof (posterior wall) consists of the superior medullary velum, a thin sheet of white matter, the white core of the cerebellum, and the inferior medullary velum, a thin layer of ependyma, covered by pia mater and choroid plexus.
• The lower part of the roof has 3 foramina that allow CSF to drain into the subarachnoid space:
  • Foramen of Magendie
  • Foramina of Luschka

The Floor (Pontine Part)

• Medial eminence: Longitudinal elevation on either side of the median sulcus
• Facial colliculus: Swelling at the lower end of the medial eminence.
• Superior fovea: Groove lateral to facial colliculus
• Vestibular area: Lateral to superior fovea, overlying the vestibular nuclei.

The Floor (Medullary Part)

• Inferior fovea: An inverted V-shaped groove.
• Hypoglossal trigone: Close to the midline, produced by the hypoglossal nucleus.
• Vagal trigone: Between the two limbs of the inferior fovea, and produced by the dorsal nucleus of the vagus nerve.
• Vestibular trigone: Situated laterally, produced by the inferior vestibular nucleus.

The Arterial Supply

• The cerebellum is supplied by three main arteries: superior cerebellar artery, anterior inferior cerebellar artery, and posterior inferior cerebellar artery. These arteries branch from the basilar artery.

The Communications

• Cerebrospinal fluid (CSF) exits the fourth ventricle through 3 foramina.
• CSF circulates through the subarachnoid space and communicates with other ventricles through the cerebral aqueduct and central canal.

Functional Division

• The cerebellum is divided into three functional parts:
  • Vestibulocerebellum: Involved in balance and eye movements.
  • Spinocerebellum: Regulates muscle tone and movement coordination.
  • Cerebrocerebellum: Associated with motor planning, learning, and memory.