Brain stem

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Adult human brain , parts of the brain stem ( truncus cerebri ) highlighted in red
Early embryonic stages of the vertebrate brain -
left half of the picture: 3-vesicle stage, right half of the picture: 5-vesicle stage.

When the brain stem , trunk cerebri or truncus encephali ( latin truncus "trunk, trunk") of the below are diencephalon (diencephalon) localized areas of the brain , excluding the cerebellum (cerebellum), respectively.

The brain stem thus includes:

The term brain stem is not synonymous with brain stem . The term brain stem stands for a term that includes not only the brain stem but also the diencephalon, and occasionally also the cerebellum and parts of the terminal brain (as basal ganglia ). However, it is not particularly useful from a developmental perspective or from a functional perspective to summarize the diencephalon with the midbrain, bridge and elongated medulla, and less so with the cerebellum and parts of the hindbrain.

The basic anatomical structures of the brain stem changed relatively little in the course of evolution compared to the phylogenetic development of the forebrain . The subdivision of the brainstem into mesencephalic, metencephalic and myelencephalic parts is most clearly recognizable on its ( ventral ) surface facing the front of the body , where the bridge is noticeable as a transverse bulge.


The brain stem controls the vital functions. For example breathing, blood pressure, reflexes etc.


Damage to the brain stem causes brain stem syndromes . Damage to the pathways to the ( caudal ) cranial nerve nuclei located downstream leads to pseudobulbar paralysis .

See also


  1. truncus in the Pons online dictionary.
  2. Martin Trepel : Neuroanatomy: Structure and Function. 4th edition. Elsevier, Urban & Fischer Verlag, Munich 2008, ISBN 978-3-437-41298-1 , page 118.