Vomer bone anatomy: the thin midline bone of the nasal septum

What it is

A thin, flat bone of the nasal septum.

Location

Lies in the midline of the nasal cavity, articulating with the sphenoid, ethmoid, maxillae and palatine bones.

Function

Forms the lower back (posteroinferior) part of the nasal septum.

Body system

Skeletal · single, midline structure

FMA ID

FMA9710 (Foundational Model of Anatomy)

Key facts

• It joins the perpendicular plate of the ethmoid and the septal cartilage.

Clinical relevance

A deviated septum may involve it.

The vomer lies in the midline between the two nasal cavities. It is an unpaired facial bone that forms the posteroinferior part of the bony nasal septum. Its surfaces face the right and left nasal cavities. (Radiopaedia: Vomer.)

OpenStax describes the vomer as triangular and forming the posterior-inferior part of the nasal septum. Seen from behind, through the posterior openings of the nose, the vomer forms the entire height of the nasal septum. (OpenStax Anatomy and Physiology 2e, 7.2: The Skull.)

The 3D model shows the vomer from the BodyParts3D adult male skull. Because it sits deep in the midline, it is easiest to see from below, looking up between the back of the hard palate and the sphenoid, or in a cut-away view of the nasal cavity.

The vomer is thin, flat and trapezoid in shape, with two surfaces and four borders. It has a vertical plate that forms most of the bone and two wing-like projections at the top, the alae of the vomer. (Kenhub: Vomer.)

The superior border is the thickest and carries the alae. A deep groove between the alae receives the rostrum (beak) of the sphenoid body. The inferior border sits on the nasal crest of the maxillae and palatine bones. The anterior border is the longest: its upper half joins the perpendicular plate of the ethmoid and its lower half the septal cartilage. The posterior border is short and concave, joins no bone, and separates the two choanae. (Radiopaedia: Vomer.)

Along the superior border, a small vomerovaginal canal is formed between each ala, the sphenoid body and the small vaginal process of the sphenoid. (Radiopaedia: Vomer.)

The vomer articulates with six bones: two maxillae and two palatine bones (facial bones), and the sphenoid and ethmoid (bones of the braincase). It also meets the septal cartilage of the nose. (Kenhub: Vomer.)

In detail, the alae meet the rostrum of the sphenoid and the sphenoidal processes of the palatine bones. The inferior border meets the median nasal crest of the maxillae and palatine bones. The anterior border meets the perpendicular plate of the ethmoid above and the septal cartilage below. (Radiopaedia: Vomer.)

The nasal septum runs from the nostrils to the choanae. Its front part is the septal (quadrangular) cartilage. Behind it, the perpendicular plate of the ethmoid forms the upper back part and the vomer the lower back part. Along the floor, the nasal crest of the maxillae and palatine bones forms a narrow bony strip that meets the lower edge of the vomer. (Radiopaedia: Nasal septum.)

Kenhub summarises the septum as three parts: the vomer, the perpendicular plate of the ethmoid and the septal cartilage. By dividing the nasal cavity, the septum helps direct airflow through each side of the nose. (Kenhub: Vomer.)

Each surface of the vomer has an oblique nasopalatine groove for the nasopalatine (sphenopalatine) nerve and vessels as they cross the septum. (Radiopaedia: Vomer.)

The nasopalatine nerve, a branch of the maxillary nerve (V2), supplies sensation to the anterior septum. Other parts of the septum are supplied by the anterior ethmoidal nerve (upper back) and nasal branches of the greater palatine nerve (lower back). The septum's arteries are the sphenopalatine, anterior and posterior ethmoidal, superior labial and greater palatine arteries. (Radiopaedia: Nasal septum.)

The nasopalatine nerve continues through the incisive canal in the front of the hard palate, which connects the lower nasal cavity with the mouth. (Radiopaedia: Incisive canal.)

The choanae are the two openings at the back of the nasal cavity that lead into the nasopharynx. The free posterior border of the vomer stands between them, so it forms the medial edge of each choana. (Kenhub: Vomer.)

In choanal atresia, one or both choanae fail to open because the bucconasal membrane does not break down. It affects about 1 in 5,000 to 8,000 births and about two-thirds of cases are one-sided. A thickened vomer is one of the CT signs. When both sides are blocked, a newborn can be in respiratory distress because babies are obligate nose breathers. (Radiopaedia: Choanal atresia.)

Some deviation of the nasal septum is extremely common. Other septal problems include septal perforation and septal haematoma. Because the vomer forms the lower back of the septum, a deviation there can affect the bony as well as the cartilaginous septum. (Radiopaedia: Nasal septum.)

An occasional variant is pneumatisation of the vomer, where the sphenoid sinus extends down into it. (Radiopaedia: Vomer.)

Both are thin midline plates of the bony septum, so they are easy to mix up on a skull. The perpendicular plate of the ethmoid forms the upper back part of the bony septum and the vomer the lower back part. The vomer's lower border rests on the nasal crest of the maxillae and palatine bones, and its free posterior border reaches the choanae. (Radiopaedia: Nasal septum.)

The two bones meet along the upper half of the vomer's anterior border, and the septal cartilage fills the angle in front of them, meeting the lower half of that border. (Radiopaedia: Vomer.)

The nearest named structures in the 3D model, measured from the centre of each part:

• Inferior nasal concha · skeletal
• Palatine bone · skeletal
• Ethmoid · skeletal
• Nasolacrimal duct · eye & ear
• Maxilla · skeletal
• Sphenoid bone · skeletal
• Short ciliary nerve · nervous
• Lacrimal bone · skeletal
• Medial rectus · muscular
• Inferior rectus · muscular