The four major paranasal sinuses are the maxillary, ethmoid, sphenoid, and frontal sinuses. These air-filled spaces are located within the bones of the face and skull, connecting to the nasal cavity.
Understanding the Paranasal Sinuses
The term "sinus," in common usage, refers to the paranasal sinuses located near the nose. These sinuses are paired, meaning there are two of each type, one on each side of the face. They're named after the bones in which they reside:
- Maxillary Sinuses: Located within the maxillary bones (cheekbones), these are the largest of the paranasal sinuses.
- Ethmoid Sinuses: Situated within the ethmoid bone, which is between the eyes and nasal cavity, these are a group of small, interconnected air cells.
- Sphenoid Sinuses: Found within the sphenoid bone, deep within the skull behind the nose, these are the most posterior paranasal sinuses.
- Frontal Sinuses: Located within the frontal bone (forehead), these sinuses develop later in childhood and are situated above the eyes.
While there are other sinuses in the body, such as those found in the dura mater of the brain (e.g., superior sagittal, straight, and sigmoid sinuses), these are typically not referred to as the major sinuses when discussing the sinuses of the face and nose. The references provided consistently emphasize the four paranasal sinuses listed above as the primary focus when discussing sinuses in relation to the nasal cavity and head. It is important to note that the references highlight the paranasal sinuses as the most commonly understood definition of "sinus."
