myelencephalon


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myelencephalon

 [mi″el-en-sef´ah-lon]
1. the posterior part of the rhombencephalon, comprising the medulla oblongata and lower part of the fourth ventricle.
2. the posterior of the two brain vesicles formed by specialization of the rhombencephalon in the developing embryo.

me·dul·la ob·lon·ga·'ta

[TA]
the most caudal subdivision of the brainstem, immediately continuous with the spinal cord, extending from the lower border of the decussation of the pyramid to the pons; its anterior (ventral) surface resembles that of the spinal cord except for the bilateral prominence of the inferior olive; the posterior (dorsal) surface of its upper half forms part of the floor of the fourth ventricle. Motor nuclei of the medulla oblongata include the hypoglossal nucleus, the dorsal motor nucleus, inferior salivatory nucleus, and the nucleus ambiguus; sensory nuclei include the nuclei of the posterior column (gracile and cuneate), the cochlear and vestibular nuclei, the middle and caudal portions of the spinal trigeminal nucleus, and the nucleus of the solitary tract.
See also: medulla.
Synonym(s): myelencephalon [TA], oblongata

myelencephalon

(mī′ə-lĕn-sĕf′ə-lŏn′)
n.
1. The posterior portion of the embryonic hindbrain, from which the medulla oblongata develops.
2. The medulla oblongata of the adult brain.

my′e·len·ce·phal′ic (-sə-făl′ĭk) adj.

myelencephalon

The posterior part of the hindbrain (rhombencephalon) in the embryo, which differentiates into the medulla oblongata, the caudal end of the fourth ventricle and cranial nerves 8 to 12.

me·dul·la ob·lon·ga·ta

(mĕ-dŭl'ă ob-long-gā'tă) [TA]
The most caudal subdivision of the brainstem, continuous with the spinal cord, extending from the lower border of the decussation of the pyramid to the pons; its ventral surface resembles that of the spinal cord except for the bilateral prominence of the inferior olive; the dorsal surface of its upper half forms part of the floor of the fourth ventricle. Motor nucleiof the medulla oblongata include the hypoglossal nucleus, the dorsal motor nucleus, inferior salivatory nucleus, and the nucleus ambiguus; sensory nuclei include the nuclei of the posterior column (gracile and cuneate), the cochlear and vestibular nuclei, the mid and caudal portions of the spinal trigeminal nucleus, and the nucleus of the solitary tract.
See also: medulla
Synonym(s): myelencephalon, oblongata.
References in periodicals archive ?
The cerebellum, a layer of wrinkles, is located between the optic lobe of the below and the front of the myelencephalon (Fig.
Myelencephalon. There are two trigeminal nerves that are easy to observe in the left and right part of the myelencephalon, which are in an inverted triangle shape (Fig.
Central to the T shape aqueduct midbrain, lower part of the cerebellar abuts the myelencephalon, there are no clear boundaries (Fig.
Somatic motor nerves of cranial nerves VI and XII and the visceral motor neurons of cranial nerves V, VII, IX, X and XI are developed from the myelencephalon. The rostral neural tube is contiguous with the myelencephalon and forms the spinal cord.