Vomer

The vomer (from Latin vomer, -ĕris, "ploughshare") is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and touches the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones.

Vomeronasal organ
The vomeronasal organ, also called Jacobson's organ, is a chemoreceptor organ named for its closeness to the vomer and nasal bones, and is particularly developed in animals such as cats (who adopt a characteristic pose called the Flehmen reaction or flehming when making use of it), and is thought to have to do with the perception of certain pheromones.

Anatomical details
The vomer is situated in the median plane, but its anterior portion is frequently bent to one or other side.

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.

The surfaces are marked by small furrows for blood vessels, and on each is the nasopalatine groove, which runs obliquely downward and forward, and lodges the nasopalatine nerve and vessels.

The superior border, the thickest, presents a deep furrow, bounded on either side by a horizontal projecting ala of bone; the furrow receives the rostrum of the sphenoid, while the margins of the alæ articulate with the vaginal processes of the medial pterygoid plates of the sphenoid behind, and with the sphenoidal processes of the palatine bones in front.

The inferior border articulates with the crest formed by the maxillæ and palatine bones.

The anterior border is the longest and slopes downward and forward. Its upper half is fused with the perpendicular plate of the ethmoid; its lower half is grooved for the inferior margin of the septal cartilage of the nose.

The posterior border is free, concave, and separates the choanae. It is thick and bifid above, thin below.

Articulations
The vomer articulates with six bones:
 * two of the cranium, the sphenoid and ethmoid.
 * four of the face, the two maxillae; and the two palatine bones.

It also articulates with the septal cartilage of the nose.

Trivia
By alternately thrusting with the tongue against the roof of the mouth and pressing with one of the fingers between the two eyebrows, one can articulate the vomer bone. This process, repeated for about 20 seconds, will cause the sinuses to discharge, thus rapidly clearing a stuffy head without the use of drugs.