from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of or pertaining to the base of the sphenoid bone, especially to a centre of ossification there in the embryo
- n. The basisphenoid bone
from the GNU version of the Collaborative International Dictionary of English
- adj. Of or pertaining to that part of the base of the cranium between the basioccipital and the presphenoid, which usually ossifies separately in the embryo or in the young, and becomes a part of the sphenoid in the adult.
- n. The basisphenoid bone.
from The Century Dictionary and Cyclopedia
- In anatomy, pertaining to the body or basis of the compound sphenoid bone.
- n. In anatomy, the centrum of the second cranial segment, or basis, of the compound sphenoid bone, represented in human anatomy by the greater part of the body of the sphenoid (all that part behind the sella turcica), as distinguished from its wings and pterygoid processes, situated in the basicranial axis of the skull, between the basioccipital and the presphenoid.
- n. In ichthyology, a bone attached to the anterior end of the inner wings of the proötics, which roof the myodome.
Sorry, no etymologies found.
The hinder parts of the trabeculæ become enclosed by two processes of the basisphenoid; their front parts remain in a vestigial and cartilaginous state alongside the presphenoid.
As an example of serial homology we might take the centra of the vertebræ -- the vomer, the presphenoid, the basisphenoid, the basioccipital and the series of centra in the spinal column.
The next bone, however, the basisphenoid, develops in front of the notochord, and shows very little analogy with a vertebral body.
The basisphenoid develops, like the basioccipital, in the flat _basis cranii_, but towards its anterior edge, between the large foramen (_h_) and the pituitary space (_i_).
The basilar plate and the trabeculæ, which are developed from the chorda sheath, give origin to three bones, which might possibly be considered equivalent to vertebral centra -- the basioccipital, the basisphenoid, and the _Riechbein_ (ethmoid).
Vertebrates consists, according to Müller, of three vertebræ, whose centra are the basioccipital, the basisphenoid and the presphenoid.
The basisphenoid appears in the basilar plate, but in front of the notochord, nor does it arise in exactly the same way as the centrum of a vertebra.
The analogy is even more far-fetched when applied to the axial bones in front of the basisphenoid.
The side parts of the basisphenoid and presphenoid (forming the alisphenoids and the orbitosphenoids respectively) develop in cartilage separately from the cranial basis, not like the exoccipitals in continuity with it.
The basisphenoid with the alisphenoids, which develop independently in the side walls of the brain, may, however, still be considered as forming a vertebra, though the resemblance is not so great as in the case of the occipital ring.
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