THE SUPERIOR MAXILLARY BONES. 129 
sharp edge of the nasal notch; above and in front it is continuous with the inner 
surface of the frontal process, behind which it is deeply channelled by the lachrymal 
groove, which is converted into a canal by articulation with the Jachrymal and 
inferior turbinated bones. The channel so formed conveys the nasal duct from the 
orbital cavity above to the inferior nasal meatus below. Behind this groove the 
upper edge of this area corresponds to the inner margin of the orbital surface, and 
articulates from before backwards with the lachrymal, os planum of the ethmoid, 
and the orbital process of the palate bone. The posterior border, rough for 
articulation with the palate bone, is traversed obliquely from above downwards and 
slightly inwards by a groove, which, by articulation with the palate bone, is con- 
verted into the posterior palatine or palato-maxillary canal which transmits the 
descending palatine artery and great palatine nerve. Towards its upper and hinder 
part the nasal surface of ‘the body displays the irregular, more or less triangular, 
opening of the antrum (sinus maxillaris). This aper rture, which, in the ar ticulated 
skull opens into the middle meatus of the nose, is much reduced in size by articula- 
tion with the ethmoid, palate, and inferior turbinal bones. In front of the 
lachrymal groove, the inner surface is ridged horizontally by the inferior turbinated 
crest (crista conchalis), to which the inferior turbinated bone is attached. 
Below this, the bone forms the outer wall of the inferior nasal meatus, receiving 
the termination of the lachrymal groove. Above, and for some little distance also 
on the inner side of the frontal process, it constitutes the smooth outer wall of the 
atrium of the middle meatus. 
The zygomatic or malar process (processus zygomaticus), which is placed on 
the outer surface of the body, is confluent anteriorly with the facial surface of the 
body ; posteriorly, where it is concave from side to side, with the zygomatic surface ; 
whilst superiorly, where it is rough and articular, it forms the apex of the triangular 
orbital plate, and supports the malar bone. Inferiorly, its anterior and posterior 
surfaces meet to form an arched border, which fuses with the alveolar process 
opposite the root of the first molar tooth, and serves to separate the facial from the 
zygomatic aspects of the body. 
The frontal or nasal process (processus frontalis) rises from the upper and 
fore part of the body. It has two surfaces—one external, the other internal. The 
external is divided into two by a vertical ridge (crista lachrymalis anterior), which 
is the upward extension of the infra-orbital margin. The narrow strip of bone 
behind this ridge is hollowed out, and leads into the lachrymal groove below. 
Posteriorly the edge of the frontal process here articulates with the lachrymal, and 
so forms the fossa for the lodgment of the lachrymal sac (fossa sacci lacrimalis). 
In front of the vertical crest, to which the tendo oculi is attached, the external 
surface is confluent below with the facial aspect of the body, and forms the side of 
the root of the nose. Its anterior edge is rough, or grooved, for articulation with 
the nasal bone. Superiorly the summit of the process is serrated for articulation 
with the frontal bone. The inner surface of the nasal process is directed towards 
the nasal fosse. It is crossed obliquely from below upwards and backwards by a 
ridge—the agger nasi or superior turbinated crest (crista ethmoidalis). Below this 
the bone is smooth and forms the upper part of the atrium, whilst the ridge itself 
articulates posteriorly with the fore part of the middle turbinated process of the 
ethmoid bone. 
The alveolar process (processus alveolaris) projects from the under surface of 
the body of the bone below the level of the palatal process. Of curved form, it 
completes, with its fellow of the opposite side, the alveolar arch, in which are 
embedded in sockets or alveoli the roots of the teeth of the upper jaw; ordinarily 
in the adult, when dentition is complete, each alveolar process supports eight teeth. 
Piercing the inner surface of the alveolar border behind the incisor teeth two 
small vascular foramina are usually visible. When any or all the teeth are shed 
the alveoli become absorbed, and the process may under these circumstances be 
reduced to the level of the plane of the palatal process. Posteriorly the alveolar 
process ends below the tuberosity of the body; anteriorly it shares in the formation 
of the intermaxillary suture. 
The palatal process (processus palatinus), of the form of a quadrant, lies in the 
