Hindbrain
| Hindbrain | |
|---|---|
 | |
 Scheme of roof of fourth ventricle. | |
| Identifiers | |
| MeSH | D012249 |
| NeuroNames | 540 |
| NeuroLex ID | birnlex_942 |
| TA98 | A14.1.03.002 |
| FMA | 67687 |
| Anatomical terms of neuroanatomy | |
The hindbrain or rhombencephalon is a developmental categorization of portions of the central nervous system in vertebrates. It includes the medulla, pons, and cerebellum. Together they support vital bodily processes.[1]
The hindbrain can be subdivided in a variable number of transversal swellings called rhombomeres. In the human embryo eight rhombomeres can be distinguished, from caudal to rostral: Rh8-Rh1. Rostrally, the isthmus demarcates the boundary with the midbrain.
A rare disease of the rhombencephalon—"rhombencephalosynapsis"—is characterized by a missing vermis resulting in a fused cerebellum. Patients generally present with cerebellar ataxia.
The caudal rhombencephalon has been generally considered as the initiation site for neural tube closure.[2]
Myelencephalon
Rhombomeres Rh8-Rh4 form the myelencephalon.
The myelencephalon forms the medulla oblongata in the adult brain; it contains:
- a portion of the fourth ventricle,
- the glossopharyngeal nerve (CN IX),
- vagus nerve (CN X),
- accessory nerve (CN XI),
- hypoglossal nerve (CN XII),
- and a portion of the vestibulocochlear nerve (CN VIII).
Metencephalon
Rhombomeres Rh3-Rh1 form the metencephalon.
The metencephalon is composed of the pons and the cerebellum; it contains:
- a portion of the fourth ventricle,
- the trigeminal nerve (CN V),
- abducens nerve (CN VI),
- facial nerve (CN VII),
- and a portion of the vestibulocochlear nerve (CN VIII).
Evolution
The hindbrain is homologous to a part of the arthropod brain known as the sub-oesophageal ganglion, in terms of the genes that it expresses and its position in between the brain and the nerve cord.[3] On this basis, it has been suggested that the hindbrain first evolved in the Urbilaterian - the last common ancestor of chordates and arthropods - between 570 and 555 million years ago.[3][4]
Additional images
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Chicken embryo of thirty-three hours’ incubation, viewed from the dorsal aspect. X 30. -
Human embryo between eighteen and twenty-one days. -
Hindbrain of human embryo
References
- Haycock DE (2011). Being and Perceiving. Manupod Press. p. 41. ISBN 978-0-9569621-0-2.
- ^ "Brain atlas - Hindbrain". Lundbeck Institute - Brain explorer. Retrieved 2015-06-08.
- ^ SpringerLink - Journal Article
- ^ a b Ghysen A (2003). "The origin and evolution of the nervous system". Int. J. Dev. Biol. 47 (7–8): 555–62. PMID 14756331.
- ^ Haycock, DE Being and Perceiving
External links
