Rakesh Chandra, MD
Zara Patel, MD
The paranasal sinuses (“the sinuses”) are air-filled cavities located within the bones of the face and around the nasal cavity and eyes. Each sinus is named for the bone in which it is located:
The pink membranes lining the sinuses make mucus that is cleared out of the sinus cavities and drains into the nasal passage. The right and left nasal passages are separated in the middle by a vertical plate of cartilage and bone called the nasal septum (figures 1 and 2). The sidewall of each nasal passage is lined by three ridges of tissue, and each of these is called a turbinate or concha (figures 1, 2, and 3). Specifically they are designated as inferior, middle, or superior depending on whether one is referring to the lower, middle, or upper structure. (You can see Patient Education topic Nasal Anatomy to read more about this).
Most of the sinuses drain from underneath the middle turbinate, into a region called the osteomeatal complex (figure 2). When air flows through the nasal passage on each side, it streams through the crevices between the nasal septum and these turbinates. Both airflow and mucus ends up in a part of the throat called the nasopharynx (the very back of the nose, where it meets the rest of the mouth and throat). Air is then breathed into the windpipe and lungs, while the mucus is swallowed (figure 3).
Other interesting structures associated with the nasal and sinus tract:
Figure 1: Head-on view of face.
Figure 2: CT scan through the face at he level of the maxillary and ethmoid sinuses. Note how the ethmoids are really a honeycomb like structure of small sinuses. The nasal septum (S) and middle turbinates (T) are labeled. The shaded ovals represent the osteomeatal complexes.
Figure 3: side view of face showing path of nasal airflow (arrows). Other important areas are labeled as indicated:
F – frontal sinus
S - sphenoid sinus
ST – superior turbinate
MT - middle turbinate
IT – inferior turbinate
E – eustachian tube opening
A – Adenoid
©American Rhinologic Society