The vomer (; ) is one of the unpaired

facial bones The facial skeleton comprises the ''facial bones'' that may attach to build a portion of the skull. The remainder of the skull is the neurocranium. In human anatomy and development, the facial skeleton is sometimes called the ''membranous viscer ...

of the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. 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 perpendicular plate of the ethmoid bone (vertical plate) is a thin, flattened lamina, polygonal in form, which descends from the under surface of the cribriform plate, and assists in forming the septum of the nose; it is generally deflected ...

. 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 The nasopalatine nerve (also long sphenopalatine nerve) is a nerve of the head. It is a sensory branch of the maxillary nerve (CN V2) that passes through the pterygopalatine ganglion (without synapsing) and then through the sphenopalatine foramen ...

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 Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...

of the sphenoid, while the margins of the alae articulate with the vaginal processes of the

medial pterygoid plate The pterygoid processes of the sphenoid (from Greek ''pteryx'', ''pterygos'', "wing"), one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone unite. Each process consists of a med ...

s 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 bone In anatomy, the palatine bones (; derived from the Latin ''palatum'') are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxilla, they comprise the hard palate. Stru ...

s. 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

choana The choanae (: choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the pharynx, in humans and other mammals (as well as crocodilians and most skinks). They ...

e, 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

s. It also articulates with the septal cartilage of the nose.

Vomeronasal organ

The

vomeronasal organ The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth (the hard palate) in various tetrapods ...

, also called Jacobson's organ, is a

chemoreceptor A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance ( endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorece ...

organ named for its closeness to the vomer and

nasal bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

s, and is particularly developed in animals such as cats (who adopt a characteristic pose called the ''

Flehmen reaction The flehmen response (; from German , and Upper Saxon German ), also called the flehmen position, flehmen reaction, flehmen grimace, flehming, or flehmening, is a behavior in which an animal curls back its upper lip exposing its front teeth, in ...

'' 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

labyrinthodont "Labyrinthodontia" (Greek, 'maze-toothed') is an informal grouping of extinct predatory amphibians which were major components of ecosystems in the late Paleozoic and early Mesozoic eras (about 390 to 150 million years ago). Traditionally conside ...

s (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

e (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 ''Necturus'' is a genus of aquatic salamanders in the family Proteidae. Species of the genus are native to the eastern United States and Canada. They are commonly known as waterdogs and mudpuppies. The common mudpuppy ''(N. maculosus)'' is p ...

, 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 The hard palate is a thin horizontal bony plate made up of two bones of the facial skeleton, located in the roof of the mouth. The bones are the palatine process of the maxilla and the horizontal plate of palatine bone. The hard palate spans ...

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