Hindbrain

The hindbrain, rhombencephalon or lower brain 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.

Metencephalon

Rhombomeres Rh3-Rh1 form the metencephalon.

The metencephalon is composed of the pons and the cerebellum; it contains:

• a portion of the fourth (IV) ventricle,
• the trigeminal nerve (CN V),
• abducens nerve (CN VI),
• facial nerve (CN VII),
• and a portion of the vestibulocochlear nerve (CN VIII).

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).

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. 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.

Hindbrain diseases

A rare brain disease of the cerebellum is rhombencephalosynapsis characterized by an absent or partially formed vermis. Symptoms can include truncal ataxia. The disorder is a main feature of Gomez-Lopez-Hernandez syndrome.

References

Further reading

• Ishak, Gisele E.; Dempsey, Jennifer C.; Shaw, Dennis W. W.; Tully, Hannah; Adam, Margaret P.; Sanchez-Lara, Pedro A.; Glass, Ian; Rue, Tessa C.; Millen, Kathleen J.; Dobyns, William B.; Doherty, Dan (May 2012). "Rhombencephalosynapsis: a hindbrain malformation associated with incomplete separation of midbrain and forebrain, hydrocephalus and a broad spectrum of severity". Brain. 135 (5): 1370–1386. doi:10.1093/brain/aws065. PMC 3338925. PMID 22451504.

• Tully, Hannah M.; Dempsey, Jennifer C.; Ishak, Gisele E.; Adam, Margaret P.; Mink, Jonathan W.; Dobyns, William B.; Gospe, Sidney M.; Weiss, Avery; Phillips, James O.; Doherty, Dan (December 2013). "Persistent figure-eight and side-to-side head shaking is a marker for rhombencephalosynapsis: Persistent Head Shaking". Movement Disorders. 28 (14): 2019–2023. doi:10.1002/mds.25634. PMC 5510988. PMID 24105968.

• Poretti, Andrea; Alber, Fabienne Dietrich; Bürki, Sarah; Toelle, Sandra P.; Boltshauser, Eugen (January 2009). "Cognitive outcome in children with rhombencephalosynapsis". European Journal of Paediatric Neurology. 13 (1): 28–33. doi:10.1016/j.ejpn.2008.02.005. PMID 18407532.

• Bell, B; Stanko, H; Levine, R (July 2005). "Normal IQ in a 55-year-old with newly diagnosed rhombencephalosynapsis". Archives of Clinical Neuropsychology. 20 (5): 613–621. doi:10.1016/j.acn.2005.02.003. PMID 15905069.

• Paprocka, Justyna; Jamroz, Ewa; Ścieszka, Ewa; Kluczewska, Ewa (2012). "Isolated rhomboencephalosynapsis – a rare cerebellar anomaly". Polish Journal of Radiology. 77 (1): 47–49. doi:10.12659/PJR.882587. PMC 3389961. PMID 22802865.

1. Forebrain
2. Cranial nerves
3. Brain
4. Medulla oblongata
5. Retinoic acid
6. Metencephalon
7. Myelencephalon
8. Midbrain
9. Outline of the human nervous system
10. Central nervous system
11. Diencephalon
12. Brainstem
13. List of regions in the human brain
14. Ikejime
15. Spina bifida
16. Isthmic organizer
17. Rhombomere
18. Flexure (embryology)
19. NKX 2-9
20. Brain vesicle