It is thin, somewhat quadrilateral in shape, and forms the hinder and lower part of the nasal septum; it has two surfaces and four borders.

In amphibians and reptiles, the vomers become narrower, due to the presence of the enlarged choanae (the inner part of the nostrils) on either side, and they may extend further back in the jaw.

They are typically small in birds, where they form the upper hind part of the beak, again being located between the choanae.

[4] In some living salamanders, including the mudpuppy, the maxilla is absent and therefore the vomerine teeth fulfill a major functional role in the upper jaw.

The development of the hard palate beneath the vomer means that the bone is now located in a nasal chamber, separate from the mouth.