Our skulls contain air-filled spaces known as sinuses, which are connected to the nasal passages. These cavities, often overlooked, play a role in several bodily functions and can become noticeable when problems arise. Understanding their location and purpose helps demystify these often-troublesome areas.
Mapping Your Sinus Cavities
The human skull houses four main pairs of paranasal sinuses, each named after the facial bone where it is located. These include the frontal, maxillary, ethmoid, and sphenoid sinuses, all of which drain mucus into the nasal cavity. While they are paired, their sizes and shapes can vary, and they are rarely perfectly symmetrical.
The frontal sinuses are positioned in the forehead, just above the eyes and behind the brow ridges. These triangular-shaped cavities are the most superior of the paranasal sinuses. They typically extend into the bone above the eyebrows and back into the orbital part of the frontal bone.
Below the eyes, nestled within the cheekbones, are the maxillary sinuses. These are the largest of the paranasal sinuses, resembling pyramids in shape. Each maxillary sinus can hold approximately 15 to 20 milliliters of air.
Between the eyes, behind the bridge of the nose, lie the ethmoid sinuses. Unlike other sinuses, the ethmoid sinuses are a collection of many small, air-filled cells, often described as honeycomb-like. There can be anywhere from three to eighteen of these tiny cavities on each side.
Deep within the skull, behind the upper part of the nasal cavity and near the center of the head, are the sphenoid sinuses. These are the farthest back of all the sinuses, located within the butterfly-shaped sphenoid bone. Their size varies significantly depending on age, sex, and ethnicity.
The Role of Sinuses
These air-filled spaces perform several functions that contribute to overall well-being. One primary function is to humidify and warm inhaled air before it reaches the lungs. The mucous membrane lining the sinuses transforms dry, cold air into warmer, wetter air.
Sinuses also contribute to reducing the overall weight of the skull. These lightweight, hollow cavities help counterbalance the heaviness of the bones that make up the skull, making head movements less strenuous. They can also influence the sound and resonance of one’s voice.
Paranasal sinuses offer protection for delicate structures within the skull. They can act as a “crumple zone” or “crash zone” during head trauma, absorbing some of the impact. This protective mechanism helps shield the brain from direct impact during an injury.
Understanding Sinus Discomfort
When the tissues lining the sinuses become irritated or inflamed, mucus can build up, leading to pressure and pain. This inflammation, often called sinusitis, can cause discomfort that corresponds to the specific location of the affected sinus cavity. The sensation of pain often increases when moving the head suddenly or bending over.
Discomfort in the forehead area, particularly around or above the eyebrows, frequently points to inflammation in the frontal sinuses. This pain can be felt around the eyes and may be accompanied by a feeling of pressure behind the eyes. The pain often follows a daily cycle, increasing in the morning and subsiding later in the day.
When maxillary sinuses are affected, pain is commonly felt in the cheek area, near the upper teeth, or around the eyes. This discomfort is noticeable when pressing on the cheekbones or upper jaw. Maxillary sinus pain can also be felt in the upper teeth because their roots are close to these sinuses.
Pain between the eyes or behind the bridge of the nose often indicates issues with the ethmoid sinuses. Due to their proximity to the eyes, ethmoid sinusitis can lead to eye-related symptoms like pain or tenderness when touching the bridge of the nose. A headache behind the nose can also characterize ethmoid sinusitis.
Discomfort from the sphenoid sinuses, located deep within the head, manifests as pain behind the eyes or in the ears. This deep-seated pain can also be felt in the temples or at the back of the head. When inflamed, the pressure causes discomfort deep within the head.