The vomer (; ) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the

ethmoid The ethmoid bone (; from ) is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbit (anatomy), orbits. The cubical (cube-shaped) bone is lightweight due to a sp ...

, the left and right

palatine A palatine or palatinus (Latin; : ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman Empire, Roman times.

bones, and the left and right maxillary bones. The vomer forms the inferior part of the

nasal septum The nasal septum () separates the left and right airways of the Human nose, nasal cavity, dividing the two nostrils. It is Depression (kinesiology), depressed by the depressor septi nasi muscle. Structure The fleshy external end of the nasal s ...

in humans, with the superior part formed by the perpendicular plate of the ethmoid bone. The name is derived from the Latin word for a ploughshare and the shape of the bone.

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

; it has two surfaces and four borders. The surfaces are marked by small furrows for

blood vessel Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...

s, and on each is the nasopalatine groove, which runs obliquely downward and forward, and lodges the nasopalatine nerve and vessels.

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, 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 palatine bones. The ''anterior border'' is the longest and slopes downward and forward. Its upper half is fused with the perpendicular plate of the

; 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 choanae, and is thick and bifid above, thin below.

Articulations

The human vomer articulates with six bones: * two of the cranium, the sphenoid and

. * four of the face, two

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

e; and two palatine bones. It also articulates with the septal cartilage of the nose.

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

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

In other animals

bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...

, the vomers are flattened, paired, bones forming the anterior part of the roof of the mouth, just behind the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...

ry bones. In many species, they have teeth, supplementing those in the jaw proper; in some labyrinthodonts (extinct amphibians) the teeth on the vomers were actually larger than the primary set. In

amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

s and

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

s, 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

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s, where they form the upper hind part of the beak, again being located between the choanae. In some living

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

s, including the mudpuppy, the

is absent and therefore the vomerine teeth fulfill a major functional role in the upper jaw. In

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s, 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

Image:Sobo 1909 73.png Image:Sobo 1909 74.png Image:Sobo 1909 75.png Image:Gray173.png, Median wall of left nasal cavity showing vomer ''in situ.'' Image:Gray174.png, The vomer. Image:Gray187.png, Base of skull. Inferior surface. Image:Gray194.png, Sagittal section of skull. File:Rotation Vomer bone.gif File:Vomer.jpg, Vomer File:Slide7qqq.JPG, Vomer

References

External links

* – "Nasal Cavity: Bones" * – "Diagram of skeleton of medial (septal) nasal wall." * () * – "Nasal septum, lateral view" * * {{Authority control Bones of the head and neck Irregular bones Facial bones Flat bones