The maxillary sinus is part of the paranasal sinus system. The scientific name sinus maxillaris is derived from Latin. Medical terminology also uses the synonym maxillary sinus. The maxillary sinus features paired pneumatization spaces (cavities) in the maxillary bone (maxilla) that are equipped with respiratory ciliated epithelium.
What is the maxillary sinus?
The maxillary sinus runs laterally on either side of the nasal cavity in the upper jaw bone (maxilla) and fills it almost completely. It is among the largest of the paranasal sinuses. It is connected to the main nasal cavity via a crescent-shaped opening (hiatus semilunaris). This is located just below the middle turbinate (concha nasi media). Starting from the maxillary sinuses, the drainage point is located quite high up, which makes it difficult to transport secretions, for example rhinitis. The zygomatic bone delimits the paranasal sinuses. Due to an inflammation of the maxillary sinuses (sinusitis maxillaris), the paranasal sinuses are particularly affected. The maxillary sinus is part of a system consisting of a total of five paranasal sinuses: Frontal sinus (sinus frontalis), ethmoidal sinuses (callulae ethmoidales, arranged above the eyes), maxillary sinus (on both sides of the nose up to the jawbone), sphenoidal sinus (sinus sphenoidalis, above the nose, between the eyes), thin septum (septum sinuum frontalium, in the middle of the frontal sinus).
Anatomy and structure
As a component of the paranasal sinuses, the maxillary sinus has the shape of a three-sided pyramid. The floor of the maxillary sinus is located approximately one centimeter lower than the floor of the nose. Its maximum volume is 15 cm3. The walls are equipped with respiratory (breathable) ciliated epithelium. The maxillary sinus has various protrusions, which in technical language are called recesses. In the subsidence of the basal section, individual parts of the tooth roots may protrude into the lumen (diameter, the interior of a cavity), which is exclusively covered by the mucosa. The scientific name for this protrusion is Recessus aveolaris. The second bulge, recessus zygomaticus (bifurcation), is laterally bordered to the oszygomaticum (zygomatic bone). The maxillary sinus is bordered cranially (upward) by the orbita (eye socket), dorsally (backward) by the pterygomatic fossa (pterygopalatina), caudally (downward) by the maxillary teeth and hard palate (palatum durum), and medially by the concha nasalis inferior (inferior turbinate) and the nasal cavity. The medial wall is composed mainly of cartilaginous tissue. The maxillary sinus is located in the maxillary bone and is connected to the nasal cavity by an opening. At the bottom of the maxillary sinus are the roots of the maxillary posterior teeth. These are separated from the maxillary sinus by a thin lamella of bone. On this bone lamella is the mucosa of the maxillary sinus, through which runs in a bony canal the infraorbital nerve (direct continuation of the maxillary nerve), which exits below the eye. The position of the ostium (opening of the medial wall of the maxillary sinus) prevents the drainage of mucus when the head is in an upright position.
Function and tasks
Medically, the function of the maxillary sinus is not yet fully understood. The paired outpouchings of the nasal cavity are filled with air and lined with mucosa. They are part of the respiratory system, so they are involved in heating and moistening the air, resonance amplification of the voice, and the sense of smell. The functions of the paranasal sinuses include conditioning the air we breathe and enlarging the nasal cavity. The paranasal sinuses, and thus their largest component, the maxillary sinus, are lined with a mucous membrane (mucosa) studded with cilia. These move with a time lag like a field of wheat in the wind and carry the mucus on the hairs into the nasopharynx. As a result, pathogens and harmful substances are swallowed and neutralized by the acidic environment of the stomach. The nasal cavity system also has an insulating function. Since the formation of cavities saves bone material, the paranasal sinuses ensure a reduction in the weight of the skull.
Diseases
The most common disease is maxillary sinusitis, which causes general pain, severe pressure in the head, under the eyes and in the upper jaw. If the course is chronic, these complaints remain for several weeks.The most unpleasant accompanying symptom is toothache in the upper jaw, which is not limited to just one tooth, as this discomfort simultaneously spreads to the posterior teeth of the upper jaw. The roots of these posterior teeth are located directly under the mucosa of the maxillary sinus. The dental nerves distribute through a thin network of fine ramifications at the bottom of the maxillary sinus. If inflammation or fluid accumulation occurs, or if the mucosa is swollen, this abnormal course presses on the fine nerve fibers located there. The nerves transmit the incoming pressure to the teeth in the form of toothache. The pain in the teeth may be more severe than the discomfort at the site of origin of the maxillary sinus. Maxillary sinusitis is not exclusively caused by viral or bacterial infection via the nose. If the root tips of the maxillary posterior teeth are inflamed, this inflammation can spread to the mucosa. Cysts (chronic inflammation) or granulomas on the devitalized (dead) teeth are able to dissolve the thin lamella of bone between the maxillary sinus and the root of the tooth and spread into the maxillary sinus. In many patients, this process is initially painless and occurs as an incidental finding of an X-ray examination. If the inflammation originates from a tooth, this causative tooth must be treated by apicoectomy or root canal treatment. An acute viral or bacterial infection of the maxillary sinus must be treated by an otolaryngologist or an internist. Possible etiologies include disseminated periodontal (periodontal) or periapical (via the root canal) infections, oral and atrial junction, foreign bodies, and cysts. Complications may include:
- Orbital naphlegmon/abscess,
- Sinus cavernosus thrombosis,
- Brain abscess/epidural abscess,
- Osteomyelitis (infectious inflammation of the bone marrow).
- Chronic pain
An excellent therapeutic approach is also osteopathic (complementary medicine procedure) treatment. Allergic diseases such as hay fever can also cause acute discomfort. Systemic diseases with involvement of the paranasal sinuses, for example tumor diseases, occur equally frequently.
