What Are the Sinus Cavities?

The maxillary sinus is a cone-shaped cavity in the maxillary bone. The sinus wall is bony. Most of it is a thin dense bone plate with slightly cancellous bone. The thinnest part is only dense bone. The sinus wall is directly covered by the mucous membrane, and the blood vessels and nerves that govern the teeth and periodontal tissues pass through the alveolar duct in the bone or under the mucous membrane.

Maxillary sinus

The maxillary sinus is a cone-shaped cavity in the maxillary bone. The sinus wall is bony. Most of it is a thin dense bone plate with slightly cancellous bone. The thinnest part is only dense bone. The sinus wall is directly covered by the mucous membrane, and the blood vessels and nerves that govern the teeth and periodontal tissues pass through the alveolar duct in the bone or under the mucous membrane.

The sinuses are bony cavities that contain air around the nasal cavity. There are four pairs, the frontal sinuses.

The shape of the maxillary sinus is basically the same as

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The maxillary sinus has 5 walls.

1. Anterior wall: The center is thin and concave, which is called canine fossa. It enters the sinus cavity from Caldwell-Luc operation. There is a suborbital foramen and a suborbital cavity at 12mm above the canine fossa and below the infraorbital margin. Nerves and blood vessels pass.

2. Posterior outer wall: Adjacent to the pterygopalatine fossa and infratemporal fossa, the maxillary artery can be ligated and ligated through this; the inner pterygoid muscle is also near, so the maxillary sinus malignant tumor invades this muscle and can cause difficulty in opening.

3. Inner wall: the lower part of the outer wall of the nasal cavity. At the back of the middle nasal passage, there is a cleft called "maxillary sinus hiatus". The boundaries are: the lower boundary is the attachment of the inferior turbinate, the posterior boundary is the vertical plate of the sacrum, and the front boundary is the lacrimal process and the lower end of the lacrimal bone The upper bound is the top wall of the maxillary sinus connected to the ethmoid sinus. This bony sinus is divided into four quadrants by a cross-shaped connection of the hook process and the ethmoid process of the inferior turbinate. Only the frontal upper quadrant is the true natural sinus ostium of the maxillary sinus, and the rest is closed by double-layered mucosa and dense connective tissue, which is called the nasal cardia. The diameter of the natural maxillary sinus mouth varies, with an average of 2.8 mm. Routine anterior rhinoscopy is not easy to see. When the maxillary sinus natural sinus enlargement is performed through the middle nasal passage, if you cannot find the natural sinus opening, you can first find the posterior condyle of the hook process and the upper edge of the inferior turbinate. From here, open and expand the natural sinus opening. In the endoscopic sinus surgery, the use of reverse tension forceps to expand the sinus opening should not be excessively forward, so as not to damage the nasolacrimal duct, nor should it exceed the upper boundary of the bony sinus opening, so as not to damage the paper template.

4. Upper wall: The bottom wall of the orbit is a thin layer of bone, so occupying lesions in the sinus, such as cancer and cysts, destroy this wall and invade the orbit, which can cause eye symptoms. If the wall is accidentally damaged during surgery, Can cause intraorbital infections.

5. Bottom wall: for alveolar process. The bottom wall is often separated by a thin layer of bone from the roots of the second canine, the first and second molars, so the lesions of the root can invade the sinus, causing intra-sinus lesions such as odontogenic maxillary sinusitis, and in turn the sinus lesions ( (Such as maxillary sinus cancer) can invade the root or alveolar nerve, causing tooth pain.