68 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 



Fig. 78. — The left lachrymal bone seen from its median surface (£). 



Fig. 79. — The lower half of the facial portion of the skull which has been divided horizontally, seen 



from above (\). 

 Fig. 80.— The right maxilla and palate bone, seen from the inner surfaced). 

 Fig. 81. — The right maxilla, palate bone, inferior turbinated bone and part of the ethmoid, seen from the 



inner surface (\). 



Fig. 82. — The inferior turbinated bone seen from its lateral surface (|). 



In Figs. 79 and 81 the maxilla is colored yellow, the sphenoid green, the palate bone blue, and the ethmoid 

 orange. 



The zygomatic process forms the lower portion of the outer margin of the inferior orbital (sphenomaxillary) fissure, 

 and is continued as a flat process, the orbital plate, upon the orbital surface of the body of the bone in such a manner 

 that it forms the floor of the original infraorbital groove. In young subjects this orbital plate is always separated from 

 the other bones by the infraorbital suture, which is also frequently observable in the adult skull. 



The alveolar process is convex externally, concave internally, and contains eight of the six- 

 teen upper teeth. It is directly continuous with the lower surface of the body of the bone, is sepa- 

 rated from the frontal process by the nasal notch (Fig. 77), and forms the inferior and a portion 

 of the lateral boundary of the apertura piriformis. Both alveolar processes are in contact in the 

 median line in the intermaxillary suture, and their superior margins form the anterior extremity 

 of the nasal crest and the anterior nasal spine. The free inferior margin of the process, the 

 Unions alveolaris, contains the sockets (alveoli) for the roots of the teeth, and these are separated 

 from each other by the interalveolar septa. The roots of the front teeth particularly cause the 

 walls of the alveoli to project externally and in this manner produce the juga alveolaria (Fig. 77). 



The apices of the posterior alveoli are situated immediately beneath the maxillary sinus 

 and are separated from it only by thin layers of bone (Fig. 98), and at the summit of every alveolus 

 is the orifice of an alveolar canal (see page 67). Posteriorly the alveolar process is directly 

 continuous with the tuberosity, anteriorly with the palatine process. 



The palatine processes (Figs. 79 and 100) of the two maxilke articulate in the median line 

 in the anterior portion of the middle palatine suture (Figs. 41 and 42) and form the largest portion 

 of the hard palate. Each presents a slightly concave, relatively smooth nasal surface, w T hich 

 forms the floor of the nasal fossa, and a markedly concave, extremely rough palatine surface, 

 which is directly continuous externally with the alveolar process. In the median line immediately 

 behind the junction of the two alveolar processes each palatine process exhibits upon its palatine 

 surface an incisive notch, and the corresponding notches of the two bones form the inferior 

 opening of the incisive foramen (Fig. 100), which has two orifices into the nasal fossae, one on 

 either side of the bony nasal septum (Fig. 78). The palatine surface (Fig. 100) also possesses 

 rough longitudinal ridges and grooves, the palatine spines and grooves, the latter accommodating 

 the vessels and nerves of the hard palate. 



Upon the nasal surface of the palatine processes the thickened and rolled up margins of 

 the two bones unite in the median suture to form the nasal crest (Fig. 79), into which is inserted 

 the inferior margin of the vomer. To either side of the anterior extremity of this crest is situated 

 one of the nasal orifices of the incisive canal. 



