What is the upper jaw?
The maxilla, which consists of two bones, is part of the facial skull. It consists of a stocky body (corpus maxillae) with four surfaces (facies anterior, infratemporalis, orbitalis and nasalis) and four bony processes (processus frontalis, zygomaticus, alveolaris and palatinus) extending from this body.
The maxillary body contains the paired maxillary sinus, which is lined by ciliated epithelium and is one of the paranasal sinuses.
Anterior surface of the maxillary body.
The anterior surface (facies anterior) of the maxilla, the facial surface, has an opening at its upper edge (foramen infraorbitale) through which the nerve and vessels of the same name pass into the orbit. Above this foramen, at the lower edge of the orbit, the muscle that raises the upper lips and nostrils attaches.
In the lower part of the anterior surface, there are several bony elevations – the places where the roots of the teeth are located: in the middle area, the incisor fossa, and in the canine area, the canine fossa. This is also where various muscles that move the nose and mouth attach.
Posterior surface of the body of the upper jaw
The posterior surface (facies infratemporalis) of the maxilla is separated from the anterior surface by the zygomatic process (see below) and a bony ridge that extends upward from the first molar. The infratemporal facies has a hump-like prominence (tuber maxillae) with small holes, the alveolar canals (foramina alveolaria), through which the dental nerves and dental vessels pass.
In the lower part of the posterior surface of the maxillary bone, there is a bony prominence (maxillary tuberosity) above the posterior area where the wisdom teeth erupt. Here, the maxilla is hinged to the palatine bone. In addition, a muscle that is important for jaw closure attaches here.
Upper surface of the maxillary body
The upper surface (facies orbitalis) of the maxillary bone partly forms the floor of the eye socket (orbit). Here there is a furrow which merges into the canalis infraorbitalis and in which the nerve and vessels of the same name run.
Inner surface of the upper jaw body.
The inner surface (facies nasalis) of the maxilla partially forms the lateral wall of the nasal cavity. Here lies the hiatus maxillaris, the large, irregularly square entrance into the maxillary sinus, which is bounded at the back by the bony nasal septum. The area below this opening forms the inferior nasal meatus, where the nasal meatus opens between the turbinate and the floor of the nose. Here is a canal in which the nerves and vessels supplying the palate pass.
The front of the inner surface of the upper jaw forms part of the middle nasal meatus. A bony ridge runs here, where the maxilla connects with the inferior turbinate.
Frontal process (Processus frontalis).
The frontal process (Processus frontalis) extends from the body of the upper jaw next to the nose. Various facial muscles attach here. In addition, the frontal process is involved in building the lateral wall of the nose.
Zygomatic process (Processus zygomaticus)
The zygomatic process faces the outer side of the face and connects the upper jaw to the zygomatic bone.
Dental or alveolar process (Processus alveolaris)
Behind the first molar, a cheek muscle attaches to the outer surface of the alveolar process, which is necessary for pulling the corners of the mouth sideways and pressing the lips against the cheeks and teeth. This muscle also stiffens the cheeks during sucking and pushes food between the teeth during chewing.
The alveolar process has a cancellous structure (layer of bony tubercles) whose trabeculae are arranged so that the pressure exerted on the teeth during chewing is transmitted to the maxilla.
Palatal process (Processus palatinus)
The palatine process (Processus palatinus) of the maxillary bone descends horizontally from its body and joins the opposite side in a suture (Sutura palatina mediana) and the palatine bone in another suture (Sutura palatina transversa). Together, these bones form the largest part of the hard palate.
The lower surface of the palatal process is rough and has several openings for the vessels and nerves that supply the mucosa of the palate.
Behind the upper incisors, on both sides, there are two small canals in the upper jaw, which at this point is called os incisivum (intermaxillary). The artery coming through the upper opening and the nerve pass through these canals. In the first years of life, this bone is still separated from the two bones of the upper jaw by a suture.
What is the function of the upper jaw?
The upper jaw and lower jaw with their rows of teeth are important for food intake – chewing and crushing each bite. In addition, the upper jaw is involved in building the eye socket, the nasal wall and the hard palate.
The function of the maxillary sinuses and other sinuses is not yet fully understood. Experts suggest that the air-filled bone cavities reduce the weight of the skull bones and serve as a resonating chamber for the voice.
Where is the upper jaw located?
What problems can the upper jaw cause?
A maxillary fracture is usually associated with a midface fracture.
Maxillary cysts are one of the more common conditions in the jaw. It mainly affects men between the ages of 20 and 50. Cysts develop from tissues of the dental system that remain when teeth are formed. The fluid-filled cavities grow slowly and displace surrounding tissue (teeth, nerves). Therefore, they must be surgically removed.
Directly under the floor of the maxillary sinuses are the roots of the posterior teeth of the upper jaw. The maxillary sinuses can become inflamed via the nose, to which they are connected by a canal; in the case of purulent inflammation, this is called empyema. There is pain and a feeling of pressure in the head, the upper jaw and under the eyes. Due to the only thin bone lamella between the tooth compartments and the maxillary sinus, toothache then also occurs.
Acute or chronic sinusitis is called maxillary sinusitis. It can affect one or both maxillary sinuses.
Maxillary malocclusions can be congenital, but they also result from long-term mechanical effects such as thumb sucking, poor positions of the teeth or missing teeth. If the upper jaw is too far forward, it is called antemaxillia; if it is too far back, it is called retromaxillia or maxillary hypoplasia. Both forms lead to problems with the jaw joint, tension and damage to the teeth.
