Vomer

 ( Bones Of The Head And Neck ) 

The vomer (; OED 2nd edition, 1989. Entry "vomer" in Merriam-Webster Online Dictionary. ) is one of the unpaired facial skeleton of the human skull. It is located in the midsagittal line, and articulates with the sphenoid bone, the ethmoid bone, the left and right palatine bone bones, and the left and right maxillary bone bones. The vomer forms the inferior part of the nasal septum in humans, with the superior part formed by the perpendicular plate of the ethmoid bone.Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, page 52 The name is derived from the Latin word for a ploughshare and the shape of the bone.

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In humans The vomer is situated in the median plane, but its anterior portion is frequently bent to one 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 , and on each is the vomerine groove (also nasopalatine groove or Scarpa's sulcus), which runs obliquely downward and forward, and lodges the nasopalatine nerve (also Scarpa's nerve) and vessels.

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Borders The superior border, the thickest, presents a deep furrow, bounded on either side by a horizontal projecting expansion of bone – called the wing of vomer; the furrow receives the rostrum of the sphenoid bone, while the margins of the alae 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 .

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 of bony articulation, having no muscle attachments. It is concave, separates the , and is thick and bifid above, thin below.

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Articulations The human vomer articulates with six bones:

• two of the cranium, the sphenoid bone and ethmoid bone.
• four of the face, two ; and two .

It also articulates with the septal cartilage of the nose.

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Vomeronasal organ The vomeronasal organ, also called Jacobson's organ, is a chemoreceptor organ named for its closeness to the vomer and , 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 .

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In other animals In Osteichthyes, the vomers are flattened, paired, bones forming the anterior part of the roof of the mouth, just behind the bones. In many species, they have teeth, supplementing those in the jaw proper; in some (extinct amphibians) the teeth on the vomers were actually larger than the primary set. In and , the vomers become narrower, due to the presence of the enlarged (the inner part of the nostrils) on either side, and they may extend further back in the jaw. They are typically small in , where they form the upper hind part of the beak, again being located between the choanae.

Romer, Alfred Sherwood (1977). 003910284X, Holt-Saunders International. 003910284X

In some living , including the Necturus, the maxilla is absent and therefore the vomerine teeth fulfill a major functional role in the upper jaw.

In , the vomers have become narrower still, and are fused into a single, vertically oriented bone. The development of the hard palate beneath the vomer means that the bone is now located in a nasal chamber, separate from the mouth.

== Additional images ==

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See also

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External links

• – "Nasal Cavity: Bones"
• – "Diagram of skeleton of medial (septal) nasal wall."
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• – "Nasal septum, lateral view"

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