The Anatomy of the Maxilla

The maxilla is a bone which helps to make up the skull. It is specifically located in the mid face, forms the upper jaw, separates the nasal and oral cavities, and contains the maxillary sinuses (located on each side of the nose.

One of the maxilla's most important functions is to make up the architecture of our faces and to support the rest of the viscerocranium. It technically consists of two pyramid shaped bones that are fused together in the middle.

The maxilla houses the upper teeth, forms the roof of the mouth (palate), and also the lower portion of the orbit (bones that surround and house the eyes).

Anatomy

The maxilla is centrally located within the skull and makes up the center of the face. The lower portion of the maxilla is connected to the upper teeth through the alveolar process. The roots of the teeth form grooves that extend up the anterior portion of the maxilla.

The alveolar process extends posteriorly below the maxillary sinuses and ends in the maxillary tuberosity. The alveolar process also contains channels through which the alveolar arteries, nerves, and periodontal ligaments run.

The midline area where the two pyramid-shaped bones of the maxilla fuse together via the median maxillary suture is called the palatine process. The palatine process includes the nasal floor and a portion of the hard palate.

The anterior portion of the hard palate contains the incisive canal through which the nasopalatine nerve and the sphenopalatine artery run. The palatine process also consists of the superior nasal foramina.

The most lateral portion of the maxilla is called the zygomatic process because it articulates with zygomatic bone and forms the inferior orbital rim (just below the eye). Lateral to the zygomatic process, on the anterior surface of the maxilla, is a depression known as the canine fossa.

Another depression called the zygomaticoalveolar crest is located below the zygomatic process and just above the alveolar process.

The portion of the maxilla which articulates with the frontal bone superiorly and the nasal bones medially is referred to as the frontal process. The frontal process forms several important structures including the nasolacrimal groove, the lower center of the forehead (the area in between but just below the eyebrows), and the nasal bridge.

Sinuses are easily defined as holes in the skull which decrease the weight of the skull. They are filled with air and lined with a mucous membrane. The maxillary sinuses are some of the largest sinuses in the skull. Like the maxillary bone, the maxillary sinuses are pyramid-shaped with the apex extending towards the zygomatic bone.

Function

There are multiple functions of the maxilla. It provides critical bone structure to the skull and defines the face, for example. Since it houses the upper teeth and forms a portion of the jaw, the maxilla is necessary for the process of mastication (chewing) and speaking.

The mucous membrane lining the maxillary sinuses function to warm and humidify the air we breathe and to produce mucus, which functions as an immune defense. The maxillary sinuses can be prone to disease processes including both benign and malignant growths and infections.

The maxilla forms the floor and lateral wall of the nasal cavity which are also essential for the function of breathing and the humidifcation and warming of air.

Associated Conditions

The maxilla can be affected by congenital malformation, injuries, and infections.

Cleft Palate

Cleft palate is a condition in which the hard or soft palate does not fuse properly during fetal development, leaving a gap in the roof of the mouth. It is present at birth and can cause problems with breathing, speaking, and eating, since food and fluids can be inhaled directly into the nasal cavity. It is often caused by a genetic syndrome.

Facial Fractures

Any trauma to the face can result in facial fractures involving the maxilla. These fractures are classified by healthcare professionals using the LeFort classification system for maxillary fractures.

Sinusitis

Inflammation and infection of the maxillary sinuses is not an uncommon condition and can be more likely to occur in individuals with underlying conditions such as allergies. Symptoms may include facial pain, congestion, and a runny nose.

Depending on the underlying cause, treatments may include antibiotics, allergy medications, or even sinus surgery.

Treatment and Rehabilitation

Conditions associated with the maxilla are often surgically treated. In the case of cleft palate immediate issues involving the ability to breathe or eat must first be given priority. This sometimes involves the use of breathing tubes, special bottles or feeding tubes.

Once these problems are adequately addressed the cleft palate can be surgically repaired. Sometimes multiple surgeries are required depending on the extent of the defect. Rehabilitation may include speech therapy or dental care.

The treatment of any fracture involving the maxilla depends on the extent and nature of the injury. In cases of severe trauma fractures to this part of the face may affect your ability to breathe. In this case, measures must be taken to establish a tracheotomy tube or another means to restore respiration before further evaluation and treatment can proceed.

Unfortunately, fractures in this area also often affect your ability to eat. If the fracture is small and not extensive it may heal in time with rest, a soft diet, and pain medication. Larger more extensive fractures of the maxilla may need to be surgically repaired, especially if trauma to surrounding nerves or blood vessels has been sustained.

Inflammation or infection of the maxillary sinuses (sinusitis) can be acute or chronic in nature. Acute sinusitis usually resolves within days to a few weeks while chronic sinusitis persists sometimes for months or even longer.

The sinus cavities can become infected with bacteria or other germs like fungi. In the case of a bacterial infection, antibiotics are necessary. Allergic conditions can cause persistent inflammation and swelling of the sinuses and in some cases leads to abnormal growths inside of the sinus cavities called polyps which require surgical removal.

Common treatments for sinusitis are measures to control underlying allergies and inflammation, such as antihistamines, and sometimes surgery.