sinusesfrontal

The frontal sinuses are a pair of air-filled cavities located within the frontal bone, above the orbits. They are part of the paranasal sinus system and are typically paired, but they vary in size and shape and can be asymmetrical or absent in some individuals.

Anatomy and drainage: The frontal sinuses are lined by respiratory mucosa, consisting of ciliated pseudostratified columnar epithelium with goblet cells. They drain into the nasal cavity through the frontonasal duct, which opens into the middle meatus. The sinuses extend into the frontal bone and are adjacent to the orbital roof and, in some cases, the anterior cranial fossa. Fractures or disease can affect drainage and supply, with potential intracranial implications.

Development and variation: Pneumatization of the frontal sinuses begins in late infancy and progresses through adolescence, leading to a wide range of adult sizes. Agenesis or hypoplasia occurs in a minority of individuals. The frontal sinuses often show asymmetry between the two sides.

Function: The exact primary function of the frontal sinuses is not fully established. Theories include humidifying and warming inspired air, reducing skull weight, contributing to voice resonance, and providing a buffer against facial trauma. They also affect the pattern of sinus-related diseases due to drainage pathways.

Clinical significance: Frontal sinus disease, such as frontal sinusitis or chronic rhinosinusitis with frontal involvement, presents with frontal or periorbital pain, nasal discharge, and sometimes fever. Diagnosis relies on clinical assessment and imaging, with computed tomography (CT) being the standard. Treatment may involve medical therapy and, in chronic or obstructive cases, surgical drainage or drainage-focused procedures. Frontal sinus fractures carry a risk of meningitis or orbital injury and require careful evaluation.