The =vomer= is a median unpaired bone, which assists in forming the
lower part of the septum nasi. It is composed of a thin lamina which is
bent (except in its posterior part) so as to form a narrow groove
(Sulcus septi narium), in which the lower part of the perpendicular
plate of the ethmoid bone and the septal cartilage are received. The
=lateral surfaces=, right and left, are highest near the posterior end
and diminish gradually to the anterior end; they are slightly convex
dorso-ventrally, and are covered by the nasal mucous membrane during
life. The =inferior border= is thin and free in its posterior third, and
divides the posterior nares into right and left halves; in the remainder
of its extent it is wider and is attached to the nasal crest. The
=anterior extremity= lies above the ends of the palatine processes of
the premaxillæ. The =posterior extremity= consists of two =wings= (Alæ
vomeris) which extend outward below the body of the presphenoid;
posteriorly they form a notch (Incisura vomeris), and laterally join the
palate and pterygoid bones.
=Development.=—The vomer is primitively double, and ossifies from a
center on either side in the membrane covering the cartilaginous septum
nasi; the two laminæ then fuse below and form a groove.