The upper jaw is the largest bone of the facial skull. It forms the counterpart to the lower jaw.
What is the upper jaw?
The maxilla is the largest bone of the human facial skull. Its counterpart is the lower jaw (mandible). The maxilla is formed by two paired bones. It is firmly connected to the skull. By the Maxilla it comes to the demarcation to three body cavities. These are the lateral wall of the nasal cavity (cavum nasi), the floor of the bony eye cavity (orbita) and the hard palate (pallatum durum) in the oral cavity. The maxilla also contains the maxillary sinus (sinus maxillaris), which is one of the largest cavities in the cranial region. The maxilla represents an important part of the facial skull. Thus, it is important for the intake of food and influences speech and appearance of the person. There is a firm adhesion with the zygomatic bone and the nasal bone. However, the upper jaw is only indirectly connected to the lower jaw.
Anatomy and structure
The body of the maxilla can be divided into four distinct surfaces. At the anterior margin of the body of the maxilla is the facial surface (facies anterior). At the posterior edge of the facial surface is the lower temporal surface (Facies infratemporalis). The orbital surface (facies orbitalis) of the maxilla provides the lower border of the orbit. The lateral portion of the nasal cavity boundary is formed by the nasal surface (facies nasalis). Since the upper surface of the upper jaw is not smooth and flat, there are several depressions, passages and projections on it. Between the frontal bone, the lacrimal bone and the nasal bone there is the frontal process (Processus frontalis), which serves as a connecting structure. At the lower edge of the orbital surface is the zygomatic process (Processus zygomaticus). An important task is performed by the alveolar process (Processus alveolaris), which has the shape of an arch. It supports the teeth, which are extremely important for chewing. Another structure of the upper jaw is the palatal process (Processus palatinus). This plate-shaped structure is located between the nasal surface and the alveolar process and forms the hard palate. The upper jaw is supplied by various nerves and vessels. These include the maxillary nerve, which splits off from the trigeminal nerve, the fifth cranial nerve. From this nerve cord is given off a smaller cord called the infraorbital nerve. The nerve passes through the upper jaw and supplies the teeth and bones. The maxillary artery is responsible for supplying blood to the upper jaw. This blood vessel is a direct continuation of the outer part of the carotid artery (external carotid artery).
Function and Tasks
Like the lower jaw, the upper jaw is also important for the absorption of food. The teeth play a crucial role in this process. Due to the tooth retaining apparatus, there is a relatively firm anchorage in the upper jaw. In contrast to the lower jaw, the upper jaw is not movable, since the temporomandibular joint only triggers movements of the lower jaw section. Nevertheless, just like its counterpart, it affects a person’s visual appearance. Likewise, a person’s pronunciation is affected by it. The periodontium, which belongs to both the upper and lower jaws, performs various protective functions. It is composed of different parts. These include the alveoli, which are small indentations in the jawbone. The root part of a single tooth is found in the alveoli. Other important components of the tooth-supporting apparatus are the root skin (perodontium), the tooth cementum (cementum) and the gums (gingiva propria). However, the teeth are not completely fixed in the jawbone. Each tooth is suspended from a Sharpey fiber, a collagen fiber bundle. This allows the tooth to remain relatively mobile. In addition, the pressure loads during chewing are distributed over a larger area.
Diseases
Various ailments and diseases can occur on the upper jaw. The most common injury is a fracture of the maxilla (fractura maxillae). This results in fracture lines that have typical courses. These correspond to the weak points of the bone architecture. A fracture of the maxilla is usually caused by falls, sports accidents, traffic accidents or brawls.Among facial fractures, a maxillary fracture reaches a proportion of about 15 percent. One of the most common diseases of the upper jaw is maxillary sinusitis (sinusitis maxillaris). The maxillary sinus belongs to the paranasal sinuses. The inflammation is caused by viruses or bacteria, which negatively change the mucous membrane in the sinuses. Sinusitis can be acute or chronic. The acute form is characterized by headaches, pressure sensations in the head region, considerable discomfort and high fever. The acute form sometimes progresses to the chronic form. This occurs when there is insufficient healing of an inflammation. Sinusitis can also occur after the extraction of a tooth from the upper jaw. Treatment is usually with antibiotics. In addition to injuries and diseases, deformities are also possible in the area of the upper jaw. These include cleft lip and palate, also called harelip. In Germany, about 1500 children are born with this malformation every year. It is more common in boys than in girls and can result in speech disorders. It is not uncommon for congenital jaw malocclusions to lead to a mismatch between the teeth of the upper jaw and the lower jaw. As a result, they no longer fit together exactly. As a result, there are often not only visual impairments, but also problems with eating and speaking.
