Rhombencephalon
| Rhombencephalon | |
|---|---|
 Diagram depicting the main subdivisions of the embryonic vertebrate brain. These regions will later differentiate into forebrain, midbrain and hindbrain structures. | |
 Scheme of roof of fourth ventricle. | |
| Identifiers | |
| Gray's | p.767 |
| MeSH | A08.186.211.132.810 |
| NeuroNames | hier-531 |
| NeuroLex ID | Rhombencephalon |
| Dorlands /Elsevier | r_12/12709581 |
| TA | A14.1.03.002 |
| FMA | 67687 |
| Anatomical terms of neuroanatomy | |
The rhombencephalon or hindbrain 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 or mesencephalon.
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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Chick embryo of thirty-three hours’ incubation, viewed from the dorsal aspect. X 30.
-
Embryo between eighteen and twenty-one days.
-
Hindbrain of human embryo
References
- Haycock DE (2011). Being and Perceiving. Manupod Press. ISBN 978-0-9569621-0-2.
- ↑ "Brain atlas - Hindbrain". Lundbeck Institute - Brain explorer. Retrieved 2013-06-04.
- ↑ SpringerLink - Journal Article
- ↑ 3.0 3.1 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
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Look up rhombencephalon in Wiktionary, the free dictionary. |
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