Anatomy of the Nasal Passages
The nasal passages function as a filter and air conditioner to protect the lower airways. This functionality is achieved by the complex, narrow, convoluted, and dynamic geometry of the nose. Many particles are efficiently filtered out, and infectious agents are addressed by the nasal immune system.
The inside of the front of the nose is lined with a relatively tough skin-like lining, called squamous epithelium, and hair cells, which provide a first line of defense against harmful particles from the environment. Acting as a gateway between the anterior third of the nasal cavity (roughly the visible part of the nose) and the two-thirds of the nasal cavity deep inside the head (above the roof of the mouth), the nasal valve is the narrowest part of the entire respiratory tract and disrupts inhaled airflow to help trap airborne particles in nasal secretions. The walls of the nasal valve are soft, so the shape of the nasal valve is dynamic, tending to narrow during nasal inspiration (for example, sniffing) and widen during nasal exhalation. Particles from the air are deposited on the lining of the narrow nasal valve, where they are carried down and backwards to eventually be swallowed.
Beyond the nasal valve, the nasal passages are lined mostly by membranes more like the lining of the lungs, called respiratory epithelium, which is thin and rich in blood vessels. This region is divided into a labyrinth of slit-like passages by multiple bony proturbances that fill the nose and act as “shelves” (the curling-shaped turbinate bones) and “windshields” (the uncinate processes), creating a convoluted system of nasal passages with a large surface area that prevents direct-line movement of particles too far into the nose, creates turbulence, and slows airflow. Slowing the inhaled airflow as it passes through the nasal passages allows time and provides enough surface area for the inhaled air to be warmed and moistened within fractions of a second before reaching the lungs.
The respiratory epithelium lining this region normally creates a layer of mucus that moistens and protects the delicate lining of the nose, traps unwanted substances, and has antibodies, enzymes, and other important content. This respiratory epithelium behind the nasal valve is also normally covered with cilia, which are tiny hair-like structures embedded in the mucous layer that constantly beat to sweep the nasal mucus backward and downward into the throat, helping clear unwanted substances from the air and reducing potentially hazardous exposure to the lungs.
Optinose has developed unique new Exhalation Delivery Systems (EDS) that leverage certain special aspects of nasal anatomy and physiology to improve the ability to reach high and deep into nasal passages, transforming how certain medical conditions may be treated.