Anatomy and Development of the Maxilla - The maxilla is a paired bone that consists of the body, four processes, and three surfaces. - The body of the maxilla is pyramid-shaped and contains the maxillary sinus. - The four processes of the maxilla are the zygomatic process, frontal process, alveolar process, and palatine process. - The maxilla has three surfaces: anterior, posterior, and medial. - Features of the maxilla include the infraorbital sulcus, canal, and foramen, the maxillary sinus, and the incisive foramen. - The maxilla is ossified from two centers: one for the maxilla proper and one for the premaxilla. - These centers appear during the sixth week of prenatal development and unite in the beginning of the third month. - The maxillary sinus develops as a shallow groove on the nasal surface of the bone around the fourth month of development. - The maxilla was formerly described as ossifying from six centers, including the orbitonasal, zygomatic, palatine, premaxillary, nasal, and infravomerine centers. - Changes in the maxilla occur with age, with the vertical diameter becoming the greatest due to the development of the alveolar process and the increase in size of the sinus. - The maxilla continues to grow until adulthood.

Function and Role of the Maxilla - The alveolar process of the maxillae holds the upper teeth and forms the maxillary arch. - Each maxilla assists in forming the boundaries of three cavities: the roof of the mouth, the floor and lateral wall of the nasal cavity, and the wall of the orbit. - Each maxilla also contributes to the formation of two fossae: the infratemporal and pterygopalatine, and two fissures: the inferior orbital and pterygomaxillary. - The maxilla can be fractured, often as a result of facial trauma, and is classified according to the Le Fort classification. - The maxilla provides support for the facial structure. - It helps in chewing and biting food. - The maxilla plays a role in speech production. - It contributes to the aesthetic appearance of the face. - The maxilla assists in the proper alignment of the teeth.

Maxilla in Other Animals - In most vertebrates, the foremost part of the upper jaw consists of a separate pair of bones called the premaxillae, which fuse with the maxilla proper in humans and some other mammals. - In bony fish, amphibians, and reptiles, both maxilla and premaxilla are relatively plate-like bones, forming only the sides of the upper jaw and part of the face. - In mammals, the bones have curved inward, creating the palatine process and forming part of the roof of the mouth. - Birds do not have a maxilla in the strict sense; the corresponding part of their beaks, mainly consisting of the premaxilla, is called the upper mandible. - Cartilaginous fish, such as sharks, lack a true maxilla and instead have an upper jaw formed from a cartilaginous bar.

Common Maxillary Conditions and Disorders - Cleft lip and palate can affect the maxilla. - Maxillary fractures can occur due to trauma. - Maxillary sinusitis is an inflammation of the maxillary sinuses. - Maxillary tumors or cysts can develop in the bone. - Maxillary hypoplasia is an underdevelopment of the maxilla.

Surgical Procedures Involving the Maxilla - Maxillary osteotomy is a surgical procedure to reposition the maxilla. - Le Fort I, II, and III osteotomies are specific maxillary procedures. - Maxillary sinus augmentation is a procedure to increase bone height in the maxilla. - Maxillary distraction osteogenesis is used to lengthen the maxilla. - Maxillary implant placement is a common dental procedure.