Vomer

The vomer is a small, thin, and flat facial bone that forms the inferior portion of the nasal septum. Positioned in the midline of the skull, it plays a crucial role in dividing the nasal cavity into left and right halves. Although it is a single unpaired bone, it articulates with several other cranial and facial bones to form the bony nasal septum. Despite its small size, the vomer is critical for proper airflow, nasal symmetry, and structural integrity of the midface.

Structure

The vomer is shaped like a plowshare — broad at the bottom and tapered at the top. It is a thin, flat bone composed of two lateral surfaces that meet at a midline crest. The superior border of the vomer features two wing-like processes (ala of vomer) that articulate with the sphenoid bone, forming a groove that holds the sphenoidal rostrum. Its inferior edge fuses with the hard palate, completing the lower portion of the nasal septum.

Location

The vomer is located within the nasal cavity in the sagittal plane. It lies posterior to the cartilaginous portion of the nasal septum and inferior to the perpendicular plate of the ethmoid bone. Anteriorly, it meets the septal cartilage, and inferiorly it rests on the palatine processes of the maxillae and the horizontal plates of the palatine bones.

Articulations

The vomer articulates with six bones:

• Sphenoid bone – superiorly (ala of vomer with the sphenoidal rostrum)
• Ethmoid bone – anteriorly (perpendicular plate)
• Palatine bones (2) – inferiorly (horizontal plates)
• Maxillae (2) – anteroinferiorly (palatine processes)

Additionally, the anterior margin of the vomer connects with the septal cartilage, forming the anterior part of the nasal septum.

Surfaces and Borders

1. Lateral Surfaces

• Form the medial walls of the posterior nasal cavity (choanae).
• Covered by mucosa and contribute to the nasal septum.

2. Superior Border

• Features wing-like expansions that articulate with the sphenoid bone’s rostrum.
• Forms a groove for the vomerine crest of the sphenoid.

3. Inferior Border

• Articulates with the hard palate — specifically the maxilla and palatine bones.

4. Anterior Border

• Articulates with the perpendicular plate of the ethmoid bone superiorly and the septal cartilage anteriorly.

Functions

• Structural: Contributes to the formation of the nasal septum, supporting the shape and stability of the nasal cavity.
• Respiratory: Helps separate airflow into left and right nasal passages, facilitating efficient breathing.
• Support: Serves as a bony attachment for the septal cartilage and soft tissues of the nasal cavity.

Development and Ossification

The vomer develops from the cartilaginous nasal septum and undergoes endochondral ossification. Ossification begins around the 8th week of fetal development and continues into childhood. The vomer begins as paired lamellae that later fuse to form a single median bone.

Associated Structures

• Nasal Septum: Formed by the vomer (inferiorly), perpendicular plate of the ethmoid (superiorly), and septal cartilage (anteriorly).
• Choanae: The paired openings between the nasal cavity and nasopharynx; the vomer helps form their medial boundary.

Clinical Relevance

1. Deviated Nasal Septum

One of the most common clinical conditions involving the vomer is a deviated nasal septum. Deviation may be congenital or result from trauma and often involves the vomer being displaced from the midline. Symptoms can include:

• Nasal obstruction (unilateral or bilateral)
• Snoring and sleep disturbances
• Recurrent sinus infections
• Difficulty breathing through the nose

Severe cases may require a septoplasty, a surgical procedure that repositions or removes parts of the vomer and septal cartilage to restore nasal symmetry and function.

2. Trauma and Fracture

The vomer is thin and centrally located, making it vulnerable in high-impact nasal or facial trauma. Fractures may be associated with midface injuries, Le Fort fractures, or nasal trauma. Isolated vomer fractures are rare but can contribute to nasal septal deviation or instability.

3. Surgical Access

The vomer may be removed or partially resected in certain skull base surgeries or endoscopic sinus procedures to access the sphenoid sinus, pituitary gland, or posterior nasal structures.

4. Congenital Malformations

• Choanal atresia: A congenital condition where the posterior nasal apertures are blocked, often involving abnormal development of the vomer and surrounding structures.
• Cleft palate: Incomplete fusion between the vomer and the palatine bones may contribute to clefting disorders.

Radiological Appearance

On CT scans, the vomer appears as a thin vertical midline bone forming the posterior part of the nasal septum. It is best visualized on axial and coronal sections. Radiologists assess its position, integrity, and alignment when evaluating septal deviations or nasal trauma.

Differences Between Vomer and Other Septal Structures

• Vomer: Forms the inferior bony part of the septum.
• Perpendicular plate (ethmoid): Forms the superior bony part of the septum.
• Septal cartilage: Forms the anterior, flexible portion of the septum.

Landmarks and Surgical Relevance

• Vomerine crest: Articulates with the sphenoid’s rostrum.
• Interpalatine suture: Where the vomer meets the hard palate, important in cleft palate surgery.
• Posterior nasal spine: Related to the vomer’s articulation and used in surgical navigation.

Comparison with Other Facial Bones

• The vomer is the only **unpaired** midline bone of the nasal septum (mandible is unpaired but not part of the septum).
• Unlike bones such as the maxilla or zygomatic, the vomer does not bear teeth or contribute to facial contour.
• It is purely structural and functional for nasal architecture and airflow.