from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The posterior portion of the embryonic hindbrain, from which the medulla oblongata develops.
- n. The medulla oblongata of the adult brain.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The portion of the brain composed of the medulla oblongata.
from the GNU version of the Collaborative International Dictionary of English
- n. The brain and spinal cord; the cerebro-spinal axis. Sometimes abbreviated to myelencephal.
- n. The metencephalon.
from The Century Dictionary and Cyclopedia
- n. The cerebrospinal axis; the brain and spinal cord taken together and considered as a whole.
- n. The hindmost segment of the encephalon; the afterbrain or metencephalon, more commonly called the medulla oblongata. See cuts under encephalon and brain. Huxley.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the posterior part of the hindbrain in developing vertebrates; forms the medulla oblongata in adults
Sorry, no etymologies found.
It is customary to divide the rest of the hind-brain into two parts, viz., an upper, called the metencephalon, and a lower, the myelencephalon.
On transverse section the myelencephalon at an early stage is seen to consist of two lateral walls, connected across the middle line by floor - and roof-plates (Figs. 647 and 648).
The floor and lateral walls of the myelencephalon are thickened to form the medulla oblongata; its roof remains thin, and, retaining to a great extent its epithelial nature, is expanded in a lateral direction.
Developmentally considered, the fourth ventricle consists of three parts: a superior belonging to the isthmus rhombencephali, an intermediate, to the metencephalon, and an inferior, to the myelencephalon.
It consists of (a) the myelencephalon, comprising the medulla oblongata and the lower part of the fourth ventricle; (b) the metencephalon, consisting of the pons, cerebellum, and the intermediate part of the fourth ventricle; and (c) the isthmus rhombencephali, a constricted portion immediately adjoining the mid-brain and including the superior peduncles of the cerebellum, the anterior medullary velum, and the upper part of the fourth ventricle.
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