Synonyms in the broadest sense
Truncus encephali
Introduction
The brain stem, also called truncus encepahli, consists of the following components:
- Midbrain=Mesencephalon
- Afterbrain=Metencephalon from bridge (Pons) and cerebellum
- Lengthened medulla oblangata
The brain stem of the brain comprises, from top to bottom, the midbrain, the bridge with the IV brain ventricle behind it and the adjacent cerebellum and, at the very bottom, the extended medulla, which merges into the spinal cord. The brain stem also contains the cranial nerve nuclei of the third to twelfth cranial nerves.
Midbrain
In the brain, the midbrain is 1.5 to 2 cm in size and is divided from front to back into the two brain legs (crura cerebri), the hood (tegmentum) and the four-hill plate (tectum). Below the four-mound plate, the IV. (nervus trochlearis) emerges below the four-hump plate.
Inside, the aquaeductus mesencephali (aquaeductus = water pipe) runs as a connection between the III. and IV. ventricle.
The upper cerebellar legs (pedunculi cerebellares superiores) leave the midbrain as the connection to the cerebellum. With regard to the important nuclei of the midbrain, the central cavernous gray (substantia grisea centralis = central gray matter), the formatio reticularis (“net-like formation”, nerve cell network), the substantia nigra (black matter) with melanin-containing nerve cells, and the iron-containing nucleus ruber (red nucleus) should be mentioned. Furthermore, the nuclei of the III.
and IV. are found in the midbrain. Brain nerves.
Bridge
The bridge of the brain has a structure similar to the midbrain (brain stem): Bridge foot (front), bridge cap (middle) and velum medullare (back; velum = sail, medullare = medullary). The bridge also has a connection to the cerebellum with the middle cerebellar thighs (Pedunculi cerebllares medii). The bridge hood (brain stem) also contains the Formatio reticularis, the locus caeruleus and the cranial nerve nuclei of the cranial nerves V to VIII.
Extended Mark
Also the onion-shaped extended medulla (brain stem) is three-layered in a front and rear area and between them located hood (tegmentum). At the front of the extended medulla, the two pyramids run with the pyramidal paths, whose intersection (pyramidal crossing) marks the end of the extended medulla. At the side of the pyramids are the olives, from which the lower cerebellar legs (Pedunculi cerebellares inferiores) go to the cerebellum. At the back of this part of the brain (brain stem) is the diamond-shaped pit; inside, in addition to the reticular format, there is also the area postrema (refractive center) and various cranial nerve nuclei (of the VIII, IX, X and XII cranial nerves).