Cephalic flexure
Encyclopedia
The mesencephalic flexure or cephalic flexure is the first flexure, or bend, of the embryo
nic brain
; it appears in the region of the mid-brain. In human embryos it generally occurs at the end of the 3rd week/beginning of 4th.
By means of it the fore-brain is bent in a ventral direction around the anterior end of the notochord
and fore-gut, with the result that the floor of the fore-brain comes to lie almost parallel with that of the hind-brain.
This flexure causes the mid-brain to become, for a time, the most prominent part of the brain, since its dorsal surface corresponds with the convexity of the curve. As a consequence, the cardiac plate, which was previously anterior to the forebrain, approximates its adult location in what will become the thoracic region.
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
nic brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
; it appears in the region of the mid-brain. In human embryos it generally occurs at the end of the 3rd week/beginning of 4th.
By means of it the fore-brain is bent in a ventral direction around the anterior end of the notochord
Notochord
The notochord is a flexible, rod-shaped body found in embryos of all chordates. It is composed of cells derived from the mesoderm and defines the primitive axis of the embryo. In some chordates, it persists throughout life as the main axial support of the body, while in most vertebrates it becomes...
and fore-gut, with the result that the floor of the fore-brain comes to lie almost parallel with that of the hind-brain.
This flexure causes the mid-brain to become, for a time, the most prominent part of the brain, since its dorsal surface corresponds with the convexity of the curve. As a consequence, the cardiac plate, which was previously anterior to the forebrain, approximates its adult location in what will become the thoracic region.