Cerebellum: Anatomy & Function

CerebellumAnatomy and function of cerebellum. Cerebellar peduncles
~ 8 min

In this note, we are going to discuss the anatomy and function of the cerebellum.

Cerebellum
Cerebellum
Cerebellum - inferior aspect
Cerebellum - inferior aspect
Cerebellum - sagittal section
Cerebellum - sagittal section

It’s a part of the brain, located within the posterior cranial fossa, and it is separated from the cerebrum by a dural septum called the tentorium cerebelli.

Function

The cerebellum helps us coordinate our movements, maintain balance and posture, and regulate muscle tone. It also plays a certain role in motor learning. Eventually, all these functions are realized by regulating the contraction and relaxation of skeletal muscles.

The cerebellum is connected to other major divisions of the brain and to the spinal cord. When we talk about connections, we actually mean nerve tracts. The nerve tracts of the cerebellum form three large structures called cerebellar peduncles. The superior cerebellar peduncle

Superior cerebellar peduncle
Superior cerebellar peduncle

connects the cerebellum to the midbrain,

Midbrain
Midbrain

the middle cerebellar peduncle

Middle cerebellar peduncle
Middle cerebellar peduncle

to the pons,

Pons
Pons

and the inferior cerebellar peduncle

Inferior cerebellar peduncle
Inferior cerebellar peduncle

to the medulla oblongata.

Medulla oblongata
Medulla oblongata

External features

The cerebellum consists of two cerebellar hemispheres,

Cerebellar hemispheres
Cerebellar hemispheres

connected by a so-called vermis, which literally means «worm».

Vermis
Vermis

On the surface of the cerebellum, we can see a large number of little folds, called cerebellar gyri or cerebellar folia.

Cerebellar folia
Cerebellar folia

divide the cerebellum into three structural lobes:

  • Anterior
Anterior lobe
Anterior lobe
  • Posterior
Posterior lobe
Posterior lobe
  • Flocculonodular
Flocculonodular lobe
Flocculonodular lobe

The latter consists of two flocculi and one nodule, respectively.

Flocculus
Flocculus
Nodule
Nodule

And the horizontal fissure divides the cerebellum into two surfaces: superior and inferior.

Horizontal fissure
Horizontal fissure

Numerous smaller fissures divide the lobes into a large number of lobules.

Fissures
Fissures

There are lobules of the vermis and lobules of the hemispheres (or horizontal lobules).

Internal features

The cerebellum consists of gray and white matter, just like any other division of the central nervous system.

The white matter is represented by the neuronal processes (predominantly axons) that form the cerebellar peduncles, conduct nerve impulses, and provide connections between the cerebellum and other divisions of the brain.

The gray matter consists of the neuronal cell bodies that produce nerve impulses and form the cerebellar cortex and deep cerebellar nuclei.

Cerebellar cortex
Cerebellar cortex

There are four such nuclei:

  • Dentate
Dentate nucleus
Dentate nucleus
  • Emboliform
Emboliform nucleius
Emboliform nucleius
  • Globose
Globose nucleus
Globose nucleus
  • Fastigial
Fastigial nucleus
Fastigial nucleus

Collectively, the globose and emboliform nuclei are referred to as the interposed nucleus.
These nuclei can be remembered by the following mnemonic: Don’t Eat Greasy Food.

In the center of the cerebellum, we have a particular pattern of the white matter, called the «tree of life» or the «arbor vitae».

Tree of life (arbor vitae)
Tree of life (arbor vitae)

Functional areas

In addition to the anatomical (or structural) lobes and lobules, the cerebellum has three functional areas. They are formed depending on two factors. Firstly, how long ago (in evolutionary terms) a certain structure originated, and secondly, with which elements of the nervous system it has connections.

  • So, the first one, the oldest part of the cerebellum, is called the archicerebellum and includes the flocculonodular lobe and fastigial nucleus. These structures are connected to vestibular nuclei of the CN VIII, so the second name of this area is the vestibulocerebellum. It plays a role in the maintenance of posture and balance.
  • The newer area in evolutionary terms is called the paleocerebellum. It includes the vermis, the intermediate zone of the cerebellar hemispheres, as well as the emboliform nucleus and the globose nucleus. These structures are connected to the spinal cord, so the second name of this area is the spinocerebellum. It plays a role in the regulation of muscle tone.
    Moreover, there is a particular pattern: the vermal area corresponds to the head, trunk, and proximal segments of the limbs, whereas the intermediate zone corresponds to the distal segments of the limbs.
  • And the last one, the newest portion, is called the neocerebellum. It includes the lateral parts of the cerebellar hemispheres and the dentate nucleus. They are connected to the cerebral cortex. Therefore, the second name of this area is the cerebrocerebellum. It plays a role in the coordination of voluntary motor activity.

Connections

We need to understand that perfectly calculated movement requires coordinated functioning of several parts of the nervous system at once. As we said, all the nerve tracts related to the cerebellum form three large structures known as cerebellar peduncles: superior, middle, and inferior.

Well, the first one, the superior cerebellar peduncle, consists of afferent and efferent connections.

The efferent tracts start off from the deep cerebellar nuclei:

  1. From the dentate nucleus – the dentatothalamic tract and the dentatorubrothalamic tract.
  2. From the interposed nucleus – the interpositorubrothalamic tract. Then all the information from the thalamus goes up to the cerebral cortex.
  3. And from the fastigial nucleus – the fastigiothalamic tract and the fastigiovestibular tract (or just the cerebellovestibular tract)

The afferent connections. These are mostly our mossy fibers:

  1. The ventral spinocerebellar tract from the lower limbs.
  2. The rostral spinocerebellar tract from the upper limbs.
  3. And the tectocerebellar tract from the superior and inferior colliculi.

The next, our middle cerebellar peduncle, consists only of afferent fibers from the pontine nuclei. The corticopontocerebellar fibers, that send down the motor plan from the cerebral cortex.

And the last one, the inferior cerebellar peduncle, consists of afferent and efferent connections.

The afferent tracts, our mossy and climbing fibers:

  1. The dorsal spinocerebellar tract from the Clarke nucleus.
  2. The cuneocerebellar tract from the upper limbs.
  3. The vestibulocerebellar tract from the vestibular nuclei
  4. The olivocerebellar tract from the inferior olive
  5. And the reticulocerebellar tract from the reticular formation of the brainstem

The efferent tracts:

  1. The cerebellovestibular tract to the vestibular nuclei
  2. And the cerebelloreticular tract to the reticular formation of the brainstem
Golosary

Cerebellum: Anatomy & Function

cerebellum
cerebellum
superior cerebellar peduncle
pedunculus cerebellaris superior
middle cerebellar peduncle
pedunculus cerebellaris medius
inferior cerebellar peduncle
pedunculus cerebellaris inferior
cerebellar hemispheres
hemisphaeria cerebelli
vermis
vermis
primary fissure
fissura prima
posterolateral fissure
fissura posterolateralis
anterior lobe of the cerebellum
lobus anterior cerebelli
posterior lobe of the cerebellum
lobus posterior cerebelli
flocculonodular lobe
lobulus flocculonodularis
horizontal fissure
fissura horizontalis
cerebellar cortex
cortex cerebelli
dentate nucleus
nucleus dentatus
emboliform nucleus
nucleus emboliformis
globular nucleus
nucleus globosus
fastigial nucleus
nucleus fastigii
interposed nucleus
nucleus interpositus
cerebellar folium
folium cerebelli
tree of life
arbor vitae
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