| Metencephalon | |
|---|---|
 | |
 Pons andcerebellum. | |
| Identifiers | |
| MeSH | D020540 |
| NeuroNames | 543 |
| NeuroLex ID | birnlex_965 |
| TA98 | A14.1.03.004 |
| FMA | 62003 |
| Anatomical terms of neuroanatomy | |
Themetencephalon is theembryonic part of thehindbrain that differentiates into thepons and thecerebellum. It contains a portion of thefourth ventricle and thetrigeminal nerve (CN V),abducens nerve (CN VI),facial nerve (CN VII), and a portion of thevestibulocochlear nerve (CN VIII).
The metencephalon develops from the higher/rostral half of theembryonicrhombencephalon, and is differentiated from themyelencephalon in the embryo by approximately 5 weeks of age. By the third month, the metencephalon differentiates into its two main structures, the pons and the cerebellum.
The pons regulates breathing through particular nuclei that regulate the breathing center of themedulla oblongata. Thecerebellum works to coordinate muscle movements, maintain posture, and integrate sensory information from theinner ear andproprioceptors in the muscles and joints.
At the early stages of brain development, the brain vesicles that are formed are imperative.[1] Each brain region is characterized by its own specific architecture. These regions of the brain are determined by a combination of transcription factors and the signals that change their expression.[1]
Theisthmus is the main organizing center for the tectum and the cerebellum.[2] The tectum is the dorsal part of the metencephalon. The tectum includes the superior and inferior colliculli, which play a part in visual andaudio processing. Two of the major genes that affect the metencephalon are Fgf8 and Wnt1, which are both expressed around the isthmus. Fgf8 is also known as Fibroblast Growth Factor 8. It is a protein that is widely thought to be the most important organizing signal. Its main function is to set up and maintain the barrier between the midbrain and hindbrain, specifically between the mesencephalon and metencephalon.[2] It also plays a large role in deciding the structure of the mid- and hindbrain. Wnt1 is a proto-oncogene protein (Wingless-type MMTV integration site family, member 1). This gene was originally thought to play a role in the development of the midbrain and hindbrain, but studies have shown that this may not be the case.[2] Wnt1 is thought to be behind the genetic disorder called Joubert Syndrome, a disorder that affects the cerebellum.
Otx1 and Otx2 are genes that play important parts in the development of the brain, and studies have shown that their roles change throughout the brain’s development.[3] It is thought that at the stage of brain development wherein the rostral brain is regionalized into its different parts (telencephalon, diencephalon, metencephalon, and mesencephalon) that Otx2 and Otx1 protect the caudalization of the diencephalon and mesencephalon into metencephalon.[3]
