There are 23 bones in the skull, some of which come in pairs. In general, the skull, excluding the mandible, appears as a single unit of joint bones (Seeley et al., 2002). Newborn’s skull consists of 45 bones, which gradually begin to fuse due to the process of osteogenesis.
The skull bones are subdivided into two groups: the facial skull and the cranial skull. The cranial vault has 8 bones that protect the brain, while the 14 facial bones form the structure of the face (Seeley et al. 2002). Facial bones named orbit, supraorbital margin, and supraorbital foramen, and infraorbital foramen provide bone support for the eyes.
The maxillary sinuses are considered to be the largest of the paranasal sinuses. Their name is based on the bones where they are located – the maxillae. (Seeley et al., 2002). They occupy the area below the orbits, are located in the right and left maxillary bones, and are paired.
The area behind the third maxillary molar is the maxillary tuberosity. On it, two or three small openings are distinguished, which lead to the alveolar canals (Seeley et al., 2002). Through these canals, the nerves pass to the posterior teeth of the upper jaw.
The mandible is divided into two parts: a curved, horizontal portion, or body, and two perpendicular portions, the rami. These parts connect with the body at almost perpendicular angles (Gallucci et al., 2011). The perpendicular portions of rami serve to form the temporomandibular joint and attach the chewing muscles.
To major landmarks of the maxillae belong labial fraenum, labial vestibule, buccal fraenum, buccal vestibule, hamular notch, and the posterior palatal seal area. The major landmarks of the mandible are mental foramen, external and internal oblique ridges, mandibular canal, submandibular fossa, and the lower border (Chen et al., 2020). Among all 22 bones, the mandible is the only movable bone.
The entire maxillae bone develops from 6 ossification points, which merge at the sixth month and form a whole bone. Foundations or so-called buttresses are of great functional importance, as they serve as conductors of chewing pressure. According to Di Ventura et al. (2019), “the new occlusal contacts (the intercuspation between the maxillary lingual cusp of upper first molars and the vestibular cusp of the mandibular first molars) during chewing can also promote torque variations in the mandibular arch” (p. 42). The mandible is located and developed around the Meckel’s cartilage. There are two main points of ossification on either side of the mandible, as well as several additional ones which appear during prenatal development. The maxillae and mandible arcs also differentiate in landscape and internal structure.
Reference
Chen, G., Al Awadi, M., Chambers, D. W., Lagravère-Vich, M. O., Xu, T., & Oh, H. (2020). The three-dimensional stable mandibular landmarks in patients between the ages of 12.5 And 17.1 years. BMC Oral Health, 20(1).
Di Ventura, A., Lanteri, V., Farronato, G., Gaffuri, F., Cossellu, G., Lanteri, C., & Beretta, M. (2019). Three-dimensional evaluation of rapid maxillary expansion anchored to primary molars: direct effects on maxillary arch and spontaneous mandibular response. European Journal of Pediatric Dentistry, 20(1), 38–42.
Gallucci, M., Capoccia, S., & Catalucci, A. (2011). Radiographic atlas of skull and brain anatomy. Springer.
Seeley, R. R., Stephens, T. D., & Tate, P. (2002). Essentials of anatomy and physiology. McGraw-Hill.