The bones of the face form, when united, a pyramid with four irregular surfaces or regions, and presenting a base above, which is connected with the cranium, an apex below at the chin.
The anterior surface or facial region presents many varieties of form and proportion in different individuals, as well as others more important, which characterise the various races of mankind : (see the article MAN.) This region is bounded above by the lower border of the frontal bone, extended between its two external angular processes: laterally it is limited by lines drawn from these processes to the anterior inferior angles of the malar bones : below this it follows the curve of the malar ridge of the upper maxilla, and it terminates at the outer extremity of the base of the lower jaw. This surface presents from above downwards along the median line, the fronto-nasal suture, which is continued laterally into the fronto-maxillary and fronto-ethmoidal sutures, all contributing to form the common transverse facial suture which unites the bones of the cranium and face. Below the fronto-nasal suture the nasal bones, united by the nasal suture, form the prominent arch of the nose in conjunction with the nasal processes of the upper maxillary bones, with which the ossa nasi articulate on each side by the naso-maxillary suture. Below the nasal bones is the anterior orifice of the nasal foss u, of a pyriform shape, narrow above, broad inferiorly, where it terminates in the projecting anterior nasal spine : the margins of this orifice are sharp, and are formed by the nasal and upper maxillary bones. Below the nasal spine is the intermaxillary suture, which terminates on the alveolar border of the upper jaw between the middle incisor teeth : on each side of this suture is the myrtiform fossa. On the lower jaw is observed, in the median line, the mental ridge and process, and on each side of it a depression for muscles.
The facial region presents from above down wards, on each side, the aperture or base of the orbit, of a quad ilateral form, and in clining from within outwards and a little back wards. The margin of this opening is formed
above by the supra-ciliary ridge of the frontal bone, in which is observed the supra-orbitar notch or foramen. At the outer extremity of this ridge is the fronto-jugal suture, uniting the external angular process of the frontal bone with the frontal process of the malar below this is the prominence of the cheek and the curved orbitar border of the malar bone, forming the outer and lower part of the margin of the orbit. Internal to this we find the short orbitar border of the upper maxillary bone, which presents at its nasal end the groove for the lachrymal sac. Below the inferior border of the orbit is the infra orbitar foramen, to the outer side of which is the oblique jugo-maxillary suture, and below it the canine fossa, bounded exter nally by the malar ridge, in front by the canine ridge and the anterior orifice of the nose, and below by the alveolar border of the jaw and by the teeth. On the lower jaw we find the teeth, the alveolar ridges and depressions, the mental foramen, and the ex ternal oblique line.
The posterior or guttural surface consists of three parts, two of which, the upper and lower, are vertical ; the middle is horizontal. The upper vertical portion presents along the median line the oblique posterior border of the vomer, which divides the posterior apertures of the nasal fosse; above is the articulation formed by the base of the vomer and the sphenoid ; below is the posterior nasal spine formed by the united palate bones. At the sides of the vomer are the oval posterior orifices of the nose, greatest in their vertical diameter, and bounded superiorly by the sphenoid and sphenoidal processes of the palate bones, inferiorly by the palatine plates of the same bones, internally by the vomer, and externally by the pterygoid processes. On the outside of these apertures are placed the pterygoid fossse, formed by the pterygoid plates of the sphenoid and by the pyramidal process of the palate bone. External to these are the large zygomatic fosses or spaces, which belong to the lateral regions of the face.