172 OSTEOLOGY. 
ethmoidal cells, and the antrum, respectively, are all thin. The cavity of the maxillary 
sinus lying to the outer side of the nasal fossze is well seen. Its roof, which separates it 
from the orbital cavity, is thin and traversed by the infraorbital canal. Its inner wall, with 
which the inferior turbinal ar ticulates, is very slender, and forms the outer walls of both 
the middle and inferior meatuses of the nose. Its outer wall is stouter where it arches 
up to bracket the zygomatic or malar process. Its floor, which rests upon the upper 
surface of the alveolar border of the upper jaw, sinks below the level of the hard palate. 
The fangs of the teeth sometimes project into the floor of the cavity. 
The nasal fosse are narrow above, where they lie between the orbital cavities, from 
which they are separated by the cells within the lateral mass of the ethmoid. The roof 
which corresponds to the cribriform plate is narrow, and lies between the septum mesially 
and the lateral masses on either side. 
At the level of the orbital- floor the nasal fossee expand laterally, the middle meatus 
running longitudinally in the angle formed by the lateral mass of the ethmoid with the 
body of the superior maxilla, overhung by the middle turbinated bone. This channel is 
seen to have the ethmoidal ells superior to it, the orbital cavity above and to the outer 
side, the antrum externally, whilst its floor is formed by the upper surface of the inferior 
turbinated bone. 
The inferior meatus, much more roomy, runs along under cover of the inferior 
turbinated bone. Externally it is related to the antrum, whilst its floor is formed by the 
concave superior surface of the hard palate. 
The hard palate is arched below, whilst its superior surface is concave upwards on 
either side of the median crest which supports the nasal septum. The sides of the arch 
below correspond to the inner surfaces of the alveolar processes and fall in line with the 
outer walls of the nasal fossee superiorly. The summit of the arch lies a quarter of an inch 
above the level of the floor of the antrum. 
SEXUAL DIFFERENCES IN THE SKULL. 
Whilst it is a matter of difficulty, in all cases, to determine with certainty the sex of 
a skull, the following points of difference are usually fairly characteristic. The female skull 
is, asa rule, smaller than the male. In point of cranial capacity it averages about a tenth 
less than the male of corresponding race. It is lighter, smoother as regards the develop- 
ment of its muscular ridges, and possesses less prominent mastoid processes. In the frontal 
region, the superciliary ridges are less pronounced, and this imparts a thinness and sharp- 
ness to the upper orbital margin, which is fairly characteristic, and can best be appre- 
ciated by running the finger along that edge of bone. For the same reason, the forehead 
appears more vertical and the projections of the frontal eminences more outstanding, though 
it is stated that the frontal and occipital regions are less capacious proportionately than in 
themale. The vertex in the female is said to be more flattened, and the height of the skull 
consequently somewhat reduced. In man the edge of the tympanic plate is generally 
sharp, and divides to form the sheath of the styloid process, whilst in the female the 
corresponding border is stated to be rounder and more tubercular. 
Whilst it is true that no one of these differences is sufficiently characteristic to enable 
us to pronounce with certainty on the matter of sex, it is the case that, taken together, 
they usually justify us in arriving at a conclusion which, as a rule, may be regarded as 
fairly accurate. In some instances, however, it is impossible to express any definite 
opinion. 
DIFFERENCES DUE TO AGE. 
At birth the face is proportionately small as compared with the cranium, constituting 
about one-eighth of the bulk of the latter. In the adult the face equals at least half the 
cranium. About the a age of puberty the development and expansion of some of the air- 
sinuses, more particularly the frontal sinus, lead to characteristic differences in head and 
face for m. 
The eruption of the teeth in early life and adolescence enables us to determine the 
age with fair accuracy. After the completion of the permanent dentition, the wear of the 
teeth may assist us in hazarding an approximate statement. The condition of the sutures, 
too, may guide us, synostosis of the coronal and sagittal sutures not as a rule taking place 
till late in life. Complete obliteration of the synchondrosis between the occipital bone 
and sphenoid may be regarded as an indication of maturity. In old age the skull 
usually becomes lighter and the cranial bones thinner. The alveolar borders of the 
