164 OSTEOLOGY. 



shape and size usually piriform, it tends to be long and narrow in Europeans, as 

 contrasted with the shorter and wider form met with in the negroid races. Its 

 edges are formed below and on either side by the free curved margin of the 

 body and the frontal process of the maxilla ; and above, and partly at the sides, 

 by the free border of the nasal bones. In the median plane, inferiorly, corresponding 

 to the upper end of the intermaxillary suture there is an outstanding process 

 the anterior nasal spine, formed by the coalescence of spicules from both maxillae ; 

 arising from this, and passing backwards and upwards, is a thin bony partition 

 the osseous septum of the nose. Often deflected to one or other side, it divides 

 the cavity of the nose (cavum nasi) into a right and a left half. Projecting into these 

 chambers from their lateral walls can be seen the medial surfaces and free borders 

 of the middle and inferior conchse, the spaces below and between which form the 

 inferior and middle meatuses of the nose, respectively. 



Below the orbit, and to the lateral side of the piriform aperture, the anterior or 

 facial surface of the body of the maxilla is seen ; this is continuous inferiorly 

 with the lateral surface of the alveolar process, in which are embedded the roots 

 of the upper teeth. 



A horizontal line drawn round the maxillse on the level of a point midway 

 between the lower borcler of the piriform aperture and the alveolar edge corre- 

 sponds to the plane of the hard palate. Below that the alveolar process separates the 

 cavity of the mouth from the front of the face ; whilst above, the large air space, 

 the maxillary sinus, lies within the body of the maxilla. 



The zygomatic bone forms the lower half of the lateral and lateral half of 

 the lower border of the orbit. Its lateral aspect corresponds to the point of 

 greatest width of the face, the modelling of which depends on the flatness or 

 projection of this bone. 



When the mandible or lower jaw is in position, and the teeth in both jaws are 

 complete, the lower dental arch will be seen to be smaller in all its diameters than 

 the upper, so that when the jaws are closed the upper teeth slightly overlap the 

 lower both in front and at the sides. Exceptionally, a departure from this arrange- 

 ment is met with. 



Lateral Aspect of the Skull (Norma Lateralis). 



Viewing the lateral aspect of the skull, in the first instance without the mandible, 

 it is seen to be formed in part by the bones of the cranium, and in part by the 

 bones of the face. A line drawn from the fronto-nasal suture to the tip of the mastoid 

 process serves to define roughly the boundary between these portions of the skull. 

 Of ovoid shape, the cranium is formed above by the frontal, parietal, and occipital 

 bones from before backwards ; whilst below, included within these are the sphenoid 

 and temporal bones. The sutures between these several bones are arranged as 

 follows : Commencing at the zygomatic process of the frontal, the suture between 

 that bone and the zygomatic bone is first seen ; tracing this backwards and a little 

 upwards, the lower edge of the frontal next articulates with the upper margin of the 

 great wing of the sphenoid for a distance varying from three-quarters of an inch to 

 one inch. Here the posterior border of the frontal turns upwards and slightly back- 

 wards, forming with the parietal the sutura coronalis (coronal suture). The lower 

 border of the parietal bone, which is placed immediately behind the frontal, articulates 

 anteriorly with the posterior part of the superior border of the great wing of the 

 sphenoid. The extent of this suture (sutura sphenoparietalis) is liable to very great 

 individual variation at times being broad, in other instances being pointed and 

 narrow, whilst occasionally the parietal does not articulate with the sphenoid at all. 

 Behind the spheno-parietal suture the parietal articulates with the squamous part 

 of the temporal (sutura squamosa), the posterior extremity of which is about one 

 inch behind the external acoustic meatus. Here the suture alters its character and 

 direction, and in place of being scaly, becomes toothed and irregular, uniting, for the 

 space of an inch or so, the mastoid angle of the parietal with the mastoid process of 

 the temporal bone. This suture (sutura parietomastoidea) is more or less horizontal 

 in direction, and lies in line and on a level with the superior border of the 

 zygomatic arch. At a point about two inches behind the external acoustic 



