The frontonasal duct is a duct through which either
frontal sinus
The frontal sinuses are one of the four pairs of paranasal sinuses that are situated behind the brow ridges. Sinuses are mucosa-lined airspaces within the bones of the face and skull. Each opens into the anterior part of the corresponding middle ...
drains into the
nasal cavity
The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nas ...
.
Each frontal sinus opens into the frontonasal duct by an opening (the ''opening of frontal sinus'' or ''frontal sinus aperture''
) on the inferomedial part
of the floor of the sinus.
The frontonasal duct passes inferior-ward
to open either
into the
middle nasal meatus
In anatomy, the term nasal meatus can refer to any of the three meatuses (passages) through the skulls nasal cavity: the superior meatus (''meatus nasi superior''), middle meatus (''meatus nasi medius''), and inferior meatus (''meatus nasi infer ...
at the anterior end of
the
ethmoidal infundibulum
The ethmoidal infundibulum is a funnel-shaped/slit-like/curved opening/passage/space/cleft upon the anterosuperior portion of the middle nasal meatus (and thus of the lateral wall of the nasal cavity) at the hiatus semilunaris (which represents the ...
,
or into the
anterior ethmoidal air cells (which then in turn drain into the nasal cavity).
The duct is lined by
mucous membrane
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...
.
Clinical significance
Frontal bone
In the human skull, the frontal bone or sincipital bone is an unpaired bone which consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bo ...
fractures may result in damage to the frontonasal duct, resulting in impaired drainage of the frontal sinus and consequent predisposition to intercranial spread of infection, and the development of
mucocele in the frontal sinus. Frontal sinus wall fractures may require the frontonasal duct to be sealed and the epithelium of the sinus to be excised.
References
Bones of the head and neck
{{Respiratory-stub