Maxillary Sinus: Definition, Function, and Examples

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Maxillary Sinus Definition

The maxillary sinus is one of four paranasal sinuses that drain into the middle meatus via the osteomeatal complex, which is located near the nose.

Maxillary Sinus Location

The maxilla, which is the fixed top bone of the jaw produced by two maxillary bones fusing together, has two maxillary sinuses, both of which are situated in the maxilla. They live in the cheekbones and are positioned laterally and somewhat below the nasal cavities of the nose.

Maxillary Sinus Anatomy

The maxillary sinus is the biggest of the four paranasal sinuses because it is the largest sinus in the body. There are three cavities in it:

1. The alveolar recess is a downward-pointing recess limited by the alveolar process of the maxilla body.

2. The zygomatic recess is a lateral recess bordered by the zygomatic bone.

3. The infraorbital recess is a downward-pointing recess bordered by the inferior orbital surface of the maxilla.

These recesses are bordered by the walls of the maxillary sinus, which are created by various sections of the surrounding bone, as previously mentioned:

1. The maxilla’s facial surface forms the anterior wall.

2. The infratemporal surface of the maxilla forms the posterior wall.

3. The orbit floor creates a superior wall.

4. The alveolar and palatine processes of the maxilla create the inferior wall.

The maxillary sinus also has a rectangular medial wall, which is largely comprised of cartilage. It is a membrane that divides the sinuses from the nasal cavity.

Nerves and blood arteries are housed in grooves in some of the walls. The Schneiderian membrane, which contains ciliated pseudostratified columnar epithelial cells that generate mucus on the internal side and periosteum on the osseous side, lines the sinus (the side with bone).

The maxillary ostium (or maxillary hiatus) is an aperture in the maxillary sinus that permits drainage from the sinus onto the posterior side of the hiatus semilunaris and ultimately into the nasal cavity’s middle meatus.

The ostium is 2.4mm in diameter and is positioned on the medial wall towards the roof of the maxillary sinus. The maxillary ostium is surrounded by cilia that beat towards it.

Maxillary Sinus Function

Though the specific functions of the maxillary sinus are unknown, scientists have speculated on a number of possibilities. One of these tasks is thought to be the maxillary sinus, which aids in warming and humidifying any breathed air before it enters the lungs.

Its also conceivable that the maxillary sinus aids the body’s defence against potentially harmful microorganisms by enriching defensive substances like lysozymes.

The maxillary sinus, along with the other three paranasal sinuses, is considered to assist in lowering the weight of the skull, allowing for better voice resonation, less strain on the neck muscles, and better balance of the head and neck, which promotes motility while standing.

Maxillary Sinus Disease

Due to many variables, such as their near proximity to the often, diseased respiratory system, the maxillary sinuses can be affected by a variety of illnesses and disorders. The following are some examples of such diseases:

i. Maxillary Sinusitis

Inflammation of the maxillary sinuses is known as maxillary sinusitis. A virus, bacterium, or fungus can cause maxillary sinusitis, although acute sinusitis is more often caused by a bacterial infection, especially following a viral upper respiratory tract illness.

Haemophilus, Streptococcus, Pneumococcus, and Staphylococcus species are the most common culprits. Hay fever and other allergens can also induce maxillary sinusitis.

Maxillary sinus pain/pressure, nasal congestion/discharge, reduced smell perception, and headache are all signs of acute maxillary sinusitis. Chronic maxillary sinusitis can occur after an acute sinusitis episode and can last for months if the antrum drains poorly into the nasal cavity.

This decrease in drainage can be caused by a variety of factors, including mechanical blockage of the ostium or mucus clearance obstruction.

Acute maxillary sinusitis is often treated solely by relieving symptoms, such as with nasal decongestants and saline irrigation of the nose. Antibiotics are rarely used unless the patient develops a fever or the infection appears to have gone beyond the sinuses.

ii. Maxillary Sinus Cancer

Tumors of both malignant and benign nature can form in the maxillary sinuses (though this is uncommon). The sinuses can be affected by a variety of cancers, including:

1. Adenocarcinoma is a kind of cancer that originates in the lining of the sinuses.

2. Lymphomas are cancers that are caused by immunological or lymphatic cells.

3. Melanomas: pigment-containing cells in the sinus lining give rise to melanomas.

4. Osteomas – noncancerous tumours that can obstruct the maxillary sinus.

Papillomas (growths that resemble warts and are caused by viral infections) can also develop in the sinuses, but the majority of them are benign. Because most individuals with maxillary sinus cancer have no symptoms early on, most tumours are only discovered after they are advanced.

If the tumour is malignant, it will have progressed to the bone around the maxillary sinus, the tissues beneath the skin, and the lymph nodes in stages 3 and 4, and it will have migrated to other areas of the body in the final stage.

The most common treatment for maxillary sinus cancer is surgical excision of the tumour followed by radiation therapy. Its effectiveness is dependent on how early the disease is detected.

Maxillary Sinus Citations
  • A comprehensive clinical review of maxillary sinus floor elevation: anatomy, techniques, biomaterials and complications. Br J Oral Maxillofac Surg . 2016 Sep;54(7):724-30.
  • Maxillary sinus augmentation. Dent Clin North Am . 2015 Apr;59(2):375-88.
  • The maxillary sinus: physiology, development and imaging anatomy. Dentomaxillofac Radiol . 2019 Dec;48(8):20190205.
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