Neuroanatomy

The cerebellum

The largest part of the hindbrain lies posterior to the pons and medulla oblongata. It is situated in the posterior cranial fossa and it is covered by the tentorium cerebelli. The cerebellum unconsciously controls the smooth contraction of voluntary muscles and carefully coordinates their action.

The cerebellum consist of two cerebellar hemispheres joined by a narrow median vermis. The cerebellum has two surfaces superior and inferior and three fissures dividing the cerebellum into three main lobes.

The superior surface of the cerebellum shows the superior aspect of the vermis, the anterior lobe, the middle (posterior) lobe, the primary and horizontal fissures.

Lobes of the cerebellum

1- The anterior lobe. 2- The middle or posterior lobe. 3- Flocculonoduler lobe.

Cerebellar lobes

Fissures of the cerebellum
1- The primary fissure seen on the superior surface of the cerebellum separate between the anterior and middle lobe( posterior lobe). 2- The uvulonodular fissure ( or posterolateral fissure) separate the flocculonodular lobe from the middle or posterior lobe of the cerebellum. 3- A deep horizontal fissure situated at the margin of the cerebellum separates the superior from the inferior surfaces, it is of no morphological or functional significance.



The inferior surface of the cerebellum shows the flocculonodular and (middle) posterior lobes and parts of the vermis ( the nodule, uvula, pyramid, and tuber). In both side of the vermis there is a part of the cerebellum called the Tonsil.

The gray matter of the cerebellum

The white mater of the cerebellum or the medulla contains The intracerebellar nuclei include: 1- Dentate nucleus. 2- Emboliform nucleus. 3- Globose nucleus. 4- Festigial nucleus.

The white mater of the cerebellum is made up of three groups: 1- Intrinsic fibers. 2- Afferent fibers. Middle and inferior cerebellar peduncles. 3- Efferent fibers. Superior cerebellar peduncle.

Cerebellar peduncles

Functionally the cerebellum divided into three parts The anterior lobe, uvula and the pyramid of the vermis constitute the Paleocerebellum which is functionally related to gross movement of the head and body.


The middle lobe except the uvula and the pyramid constitute the Neocerebellum and it is associated with the fine voluntary movement.


The flocculonodular lobe is the oldest part of the cerebellum constitute the Archicerebellum which is associated with the vestibular system.


Function of the cerebellum
Each cerebellar hemisphere controls the muscles of the same side of the body. The archicerebellum receive input from the vestibular nerve assist in maintaining equilibrium of the body by modification of the muscle tone.


The paleocerebellum receive input from the proprioceptive endings in muscles and tendons and from touch and pressure fibers it thus play a role in maintenance of posture.


The neocerebellum receive a very large input from the cerebellar cortex thus the neocerebellum facilitate a smooth coordinated voluntary movement of the body.

Sign and symptoms of the cerebellar injury

Hypotonia of the muscles. Postural changes and alteration of gait. Distribance of voluntary movement (ataxia). Disturbance of reflexes. Disturbance of ocular movement (Nystagmus). Disorder of speech (Dysarthria).

Blood supply of the cerebellum

1- Posterior inferior cerebellar arteries branches from the vertebral arteries. 2- Anterior inferior cerebellar arteries branches from the basilar artery. 3- Superior cerebellar arteies branches from the basilar artery.