Cerebellum
synonym
Medical: Cerebellum (lat.)
English: cerebrellum
anatomy
The cerebellum is a part of the brain. It lies in the posterior fossa below the posterior lobe of the cerebrum, through which it is separated by the tentorium cerebelli. The brain stem lies in front of the cerebellum.
The cerebellum can be roughly divided into 2 hemispheres (from the Greek = hemispheres), which are separated from each other by the worm (vermis, Latin). Two elongated cerebellar parts branch off from the worm on both sides; they are collectively referred to as Flocculonodular lobe (Lobus = lobes; Flocculus = flakes; Nodulus = nodules; all words come from Latin) The surface of the entire cerebellum is enlarged by innumerable folds (foliae). If you cut the cerebellum in the middle, you can see an outer, darker one bark (Cortex cerebelli) from an inner lighter mark distinguish. Within this medulla, in turn, 4 defined medullary areas can be delimited on both sides (i.e. within both hemispheres), which are referred to as cerebellar nuclei. From the outside to the inside (i.e. in the direction of the worm) are the following:
- Dentate nucleus
- Nucleus emboliformis
- Nucleus globosus
- Fastigii nucleus
where nucleus is Latin and means nucleus.
Cerebrum (1st - 6th) = endbrain -
Telencephalon (Cerembrum)
- Frontal lobe - Frontal lobe
- Parietal lobe - Parietal lobe
- Occipital lobe -
Occipital lobe - Temporal lobe -
Temporal lobe - Bar - Corpus callosum
- Lateral ventricle -
Lateral ventricle - Midbrain - Mesencephalon
Diencephalon (8th and 9th) -
Diencephalon - Pituitary gland - Hypophysis
- Third ventricle -
Ventriculus tertius - Bridge - Pons
- Cerebellum - Cerebellum
- Midbrain aquifer -
Aqueductus mesencephali - Fourth ventricle - Ventriculus quartus
- Cerebellar hemisphere - Hemispherium cerebelli
- Elongated Mark -
Myelencephalon (Medulla oblongata) - Big cistern -
Cisterna cerebellomedullaris posterior - Central canal (of the spinal cord) -
Central canal - Spinal cord - Medulla spinalis
- External cerebral water space -
Subarachnoid space
(leptomeningeum) - Optic nerve - Optic nerve
Forebrain (Prosencephalon)
= Cerebrum + diencephalon
(1.-6. + 8.-9.)
Hindbrain (Metencephalon)
= Bridge + cerebellum (10th + 11th)
Hindbrain (Rhombencephalon)
= Bridge + cerebellum + elongated medulla
(10. + 11. + 15)
Brain stem (Truncus encephali)
= Midbrain + bridge + elongated medulla
(7. + 10. + 15.)
You can find an overview of all Dr-Gumpert images at: medical illustrations
Cerebellar tonsils
A further anatomically demarcated area of the cerebellum are the so-called Cerebellar tonsils. Although they are not functionally important (at least no special function has been assigned to them so far), they play an important role in everyday clinical practice. For the following reason: in case of an increased intracranial pressurehow it can come about, for example, through impaired drainage of the cerebrospinal fluid (liquor cerebrospinale or in short: liquor) - has that brain not much opportunity to evade the pressure due to the non-stretchable bony skullcap that surrounds it. Actually, such an evasion is only possible in two places. Either brain mass is pushed into the cerebellar tent, what is called a upper entrapment or the just mentioned cerebellar tonsils are denoted by the Foramen magnum (Opening in the base of the skull) pushed out downwards (lower entrapment). In both cases there is an acute risk of damage to brain tissue, but the lower entrapment, i.e. that of the tonsils, is more feared, it can be acutely life-threatening because the respiratory center (located in the elongated medulla, i.e. the medulla oblongata, which is the lowest part of the Brain stem corresponds) is in the immediate vicinity of the entrapment and, if necessary, can also be compressed, which leads to immediate respiratory arrest.
Functionally (that is, not from a purely external point of view, but according to various functional ascriptions), the cerebellum is divided into three parts:
- 1.Spinocerebellum - Anatomically, it includes the worm and hemispherical areas adjacent on both sides
- 2.Pontocerebellum - anatomically corresponds to the lateral parts of the two hemispheres
- 3.Vestibulocerebellum - corresponds anatomically to the flocculonodular lobe
This subdivision has the following reason: The cerebellum receives information and sends information. They reach or leave it in the form of nerve cell fibers. Fibers that pull into the cerebellum and provide it with information are called Afferents (from afferre, lat = to supply). Those that leave the cerebellum to take information that was generated here elsewhere are called Efferents (from efferens, Latin = to lead out). These fibers leading in and out each run in one of the three so-called cerebellar stalks. Now it is the case that each of the three above-mentioned parts of the cerebellum receives its afferents from different parts of the body, so that it makes sense to subdivide them accordingly. The following table is intended to give a handy overview of the three components and their inputs; the names of the respective afferent fiber webs are also noted:
Cerebellar part Afferents from ... Name of the fiber web
Spinocerebellum Spinal cord spinocerebellar tract
Pontocerebellum (Cerebrocerebellum) Cerebrum via bridge (pons) pontocerebellar tract
Vestibulocerebellum Brainstem centers of the organ of equilibrium (so-called vestibular nuclei) vestibulocerebellar tract
The names of the fiber webs (Tractus, Latin = strand) can be easily derived, they are each composed of two words. The first word describes the place where the fibers originate, the second word the place where they end. For example, the pontocerebellar tract: It comes from the bridge (pons) to the Cerebellum (Cerebellum), i.e. ponto-cerebellaris.
Confusingly, there is now a further division of the cerebellum, neither functionally nor anatomically, but phylogenetically, that is, according to the phylogenetic development. The following table shows a brief summary of how the anatomical, functional and phylogenetic classification is related to one another:
Anatomically Functional phylogenetic
Worm and adjacent parts of the hemisphere Spinocerebellum Palaeocerebellum
Lateral hemispheres Pontocerebellum Neocerebellum
Flocculonodular lobe Vestibulocerebellum Archicerebellum
The Archicerebellum is the phylogenetically oldest, the neocerebellum (neo, Greek = new) the youngest part of the cerebellum.
While the medulla of the cerebellum, i.e. the part in the deep interior, mainly contains nerve fibers that run from one place to the next in the central nervous system, the cerebellar cortex contains (Cerebellar cortex) many cells. Although the cerebellum - as the name suggests - is by far not the largest part of the CNS has, the bark houses about 50% of all Neurons of the CNS. In the cerebellum, three layers can be subdivided, and each of these layers contains specific cell types.
- Molecular layer (Stratum Moleculare) - outermost layer
- Purkinje cell layer (Stratum purkinjense) - middle layer
- Master shift (Stratum granulosum) - innermost layer, adjacent to the medulla
While in the molecular layer in particular the cell bodies of Star cells and Basket cells find, the cell bodies of the are in the Purkinje cell layer Purkinje cells, the typical cells of the cerebellum. Finally, in the granular layer are the somata of Granule cells and Golgi cells.
In nerve cells, a distinction is made between excitatory and inhibitory cells, depending on which one Neurotransmitters pass them on as "information" to the next cell after they have been aroused themselves. All cells of the cerebellum are inhibitory nerve cells with GABA (short for gamma-amino-butyric acid) as neurotransmitter. Only the granule cells are exciting. Your neurotransmitter is glutamate.
