THE BONES OF THE HEAD 133 



border of the inferior maxilla. It is formed by a portion of the 

 frontal, the nasals, superior maxillae, malars, and inferior maxUla. 

 It is subdivided into two portions, frontal and facial. 



The frontal division is limited laterally by the superior temporal 

 ridge, below by the supra-orbital border at either side of the 

 median line, and by the fronto-nasal and fronto-maxillary sutures 

 close to the median line. It presents the frontal eminences, 

 superciliary ridges, external and internal angular processes, supra- 

 orbital notches, or it may be foramina, aU on either side of the 

 median line, and the nasal eminence or glabella at the median line, 

 between the two superciliary ridges. The most prominent point of 

 the glabella is known as the antinion. The meeting of the two 

 fronto-nasal sutures is known as the nasion or nasal point. The 

 centre of a line drawn from one temporal ridge to the other across 

 the narrowest part of the frontal region is known as the ophryon. 



The upper part of the facial division presents the openings of the 

 orbits. . These cavities are separated at the median line by the 

 bridge of the nose, which is formed by the nasal bones and the 

 nasal processes of the superior maxillae, whilst externally each orbit 

 is limited by the malar bone and the external angular process of 

 the frontal. The point at the inner angle of the orbit where the 

 horizontal fronto-maxillary suture meets the vertical lachrymo- 

 maxiUary suture is known as the dacryon, and the lower part of 

 the intemasal suture is known as the rhinion. Below the nasal 

 bones is the anterior nasal aperture. It is bounded on either side 

 by the nasal notch on the mesial border of the superior maxiUa, 

 and above by the inferior borders of the nasal bones, whilst 

 inferiorly in the median line is the anterior nasal spine in two 

 halves. The central point of the base of this spine is known as 

 the subnasal point. The anterior nascd aperture is the common 

 external opening of the two nasal fossae, which are separated 

 by a septum compiosed of bones and cartilage. An inspection of 

 each nasal fossa will reveal two bulging prominences on its outer 

 wall, the lower of which is formed by the inferior turbinate 

 bone, and the upper by the inferior turbinate process of 

 the ethmoid. Below the former is the inferior meatus, whilst 

 between the two is the middle meatus. The outer wall, from its 

 irregularity, thus presents a marked contrast to the floor, which is 

 smooth and imbroken. The osseous septum is, as a rule, deflected 

 to one side, most commonly the left, thus diminishing the capacity 

 of the left fossa. Below the anterior nasal aperture are the alveolar 

 borders of the superior maxillae, which lodge the upper teeth. The 

 point where the anterior margins of these two borders meet in the 

 median line is known as the alveolar point. Below these borders 

 is the entrance to the buccal cavity, and below this is the alveolar 

 border of the inferior maxilla, which lodges the lower teeth. The 

 middle point of the anterior lip of the lower border of the inferior 

 maxilla is known as the mental point or gnathion. 



The superior maxillae having a wider range than the inferior 



