THE NASAL AND SUPERIOR MAXILLARY BONES. 



189 



" Of these, the upper and lower jaws are the fundamental bones for mastication, 

 and the others are accessories : for the chief function of the facial bones is to 

 provide an apparatus for mastication, while subsidiary functions are to provide for 

 the sense-organs (eye, nose, tongue) and a vestibule to the respiratory and vocal 

 organs. Hence the variations in the shape of the face in man and the lower 

 animals depend chiefly on the question of the character of their food and their mode 

 of obtaining it." 



The Nasal Bone. 



The Nasal (nasus. the nose) are two small oblong bones, varying in size and 

 form in different individuals : they are placed side by side at the middle and upper 

 part of the face, forming, by their junction, " the bridge " of the nose. Each bone 

 presents for examination two surfaces and four borders. The outer surface is 

 concave from above downward, convex from side to side; it is covered by the 

 Pyramidalis and Compressor nasi muscles, and give attachment at its upper part 

 to a few fibres of the Occipito-frontalis muscle (Theile). It is marked by numerous 

 small arterial furrows, and perforated about its centre by a foramen, sometimes 

 double, for the transmission of a small vein. Sometimes this foramen is absent on 

 one or both sides, and occasionally the foramen caecum opens on this surface. The 

 inner surface is concave from side to side, convex from above downward; in 

 which direction it is traversed by a longitudinal groove (sometimes a canal), for 

 the passage of a branch of the nasal nerve. The superior border is narrow, thick, 

 and serrated, for articulation with the nasal notch of the frontal bone. The inferior 

 border is broad, thin, sharp, inclined obliquely downward, outward, and back- 

 ward, and serves for the attachment of the lateral cartilage of the nose. This 

 border presents, about its middle, a notch, through which passes the branch of the 

 nasal nerve above referred to. and is prolonged at its inner extremity into a sharp 



spine, which, when articulated 



With frontal bone. with the opposite bone, forms 



the nasal angle. The external 

 border is serrated, bevelled at 

 the expense of the internal sur- 

 face above and of the external 

 below, to articulate with the 

 nasal process of the superior 

 maxillary. The internal bor- 

 der, thicker above than below, 

 articulates with its fellow of 

 the opposite side, and is pro- 

 longed behind into a vertical 

 crest which forms part of the 



With 

 'opposite bone. 



Surface. 

 FIG. 152. Right nasal bone. 



With 

 frontal spine. 



Crest. 



With 



perpendicular 

 plate of 

 ethmoid. 



Groore for nasal nerve. 



Inner Surface. 

 FIG. 153. Left nasal bone. 



septum of the nose : this crest articulates with the nasal spine of the frontal above, 

 and the perpendicular plate of the ethmoid below. 



Development. By one centre for each bone, which appears about the same 

 period as in the vertebrae. 



Articulations. With four bones : two of the cranium, the frontal and ethmoid, 

 and two of the face, the opposite nasal and the superior maxillary. 



Attachment of Muscles. A few fibres of the Occipito-frontalis muscle. 



The Superior Maxillary Bones. 



The Superior Maxillary (maxilla, the jaw-bone) is one of the most important 

 bones of the face from a surgical point of view, on account of the number of diseases 

 to which some of its parts are liable. Its careful examination becomes, therefore, 

 a matter of considerable interest. It is the largest bone of the face, excepting the 

 lower jaw. and forms, by its union with its fellow of the opposite side, the whole 



1 W. W. Keen, American edition, p. 185. 



