ANTHROPOLOGY OF THE SKULL. 229 



Stephanion, the region where the curved hnes on the temporal bone cross the coronal 

 suture. 



Sub nasal 'point, in the median line at the root of the anterior nasal spine. 



Indices. — The cephalic index is the ratio of the breadth to the length of the skull 

 /ioo_xj3re^i\ The length is taken from the glabella to the occipital point, and the breadth is 



the greatest transverse diameter above the supramastoid ridge. A high index means a short 

 skull ; a low index, a long one. A skull with an index above 80 is brachycephalic ; from 75 to 

 80, mesaticephalic ; below 75, dolichocephalic. 



The index of height is the ratio of the line from basion to bregma to the length 

 ^ 100 X height \ ^ skull with an index above 75 is hypsicephalic ; from 70 to 75, orthocephalic ; 

 below 70, platycephalic. 



The facial index is the ratio of the length to the breadth of the face ( '"breadth )• '^^^ 

 length is from the nasion to the mental point, and the breadth is the greatest at the zygomatic 

 arches. A high index means a long face. A head with a facial index above 90 is leptoprosopic ; 

 one with a lower one, chauicrprosopic. In the absence of the lower jaw the index of the upper 

 face may be taken, which is almost equally valuable. The only difference is that the length is 

 taken from the nasion to the alveolar point, and that an index above 50 is leptoprosopic, and one 

 below it chatnccprosopic. 



The nasal index is the ratio of the length of the nose to the breadth ( '°°t, !"5^ ) . The 



^ \ breaath / 



length is measured in a straight line from the fronto-nasal suture to the anterior nasal spine. 

 A skull is leptorhine when the index is below 48 ; when from 48 to 53, mesorhine ; and when 

 above 53, platyrhine. 



The orbital index is the ratio of the height of the base to the breadth, thus ( '°°h nTf ^ ) • 



The breadth is a horizontal from the outer border to the point of contact of the frontal with the 

 maxilla and lachrymal. A large index means a high orbit. An orbit with an index below 84 is 

 microsenie ; with one from 84 to 89, tnesosenie ; with one above 89, niegaseine. An index of 70 

 is low for a Caucasian, and one of 106 ver>- high. The average for English skulls is said to be 88. 

 The index depends considerably on the extent to which the upper border overhangs. 



The palatal index is the ratio of the breadth to the length. The former is taken from the 

 socket of the second molar of one side to that of the other ; the latter is from the alveolar 



process in the middle line to the posterior nasal spine ( ^°° i^^ 7h — )' 



Prognathism denotes the forward projection of the face. This was formerly expressed by 

 what is known as Camper' s facial angle, which was measured on the arc between two lines 

 meeting at the nasal spine, one starting from the auricular point, the other from the most promi- 

 nent part of the forehead in the middle line (avoiding the projecting nose). This has fallen into 

 disuse owing to inherent defects, and perhaps in part to the discordant directions given for 

 drawing the lines. Flower' s gnathic index is the ratio of the line from the basion to the 



alveolar point to the line from the basion to the nasion / """ ^^''^ ^^° ^'" '"^ \ _ ^ skull is 

 •^ • V basi-nasal hne / 



orthognathous with an index below 98 ; mesognathoiis with one from 98 to 103 ; prognathous 



with one above 103. 



Shape of the Skull. — Extreme forms occur in Caucasians. The long, narrow skull, with 

 often a slight prominence along the sagittal suture, the scaphoid form, is due to the early closure 

 of the sagittal suture, and the short, round skull to that of the transverse ones. In support of this 

 theory is the fact that the metopic or median frontal suture is never found in narrow, but only in 

 broad skulls. The high, sugar-loaf, acrocephalic skull shows obliteration of all three sutures on 

 the top of the vault. The great backward occipital projection sometimes seen is usually asso- 

 ciated with many Wormian bones in the lambdoidal suture. 



The long type of skull is naturally associated with the long, narrow face, and the round 

 head with the broad face ; but the connection is not absolute. The two types of face deserve a 

 short consideration. The narroiv face has the high orbit, the narrow nose, with the aperture 

 pointed above, and a long, narrow palate. The outline of the range of teeth in one jaw to a great 

 extent determines that of the other ; but, in addition to the smaller curve, the lower jaw in this 

 form is rather delicate, is particularly likely to show the constriction in front of the masseter, 

 and has a more obtuse angle. The short and broad face has wide, low orbits, a broad and 

 almost quadrilateral opening of the nose, and a wide pair of jaws, the lower with an approxi- 

 mately square angle. If, as is most probably the case, the head is orthognathous, the edges of 

 the teeth tend to form part of an antero-posterior curve, which is particularly marked in the 

 region of the molars. It is to be noted, however, that some, or any, of these features may be 

 found in a face of the opposite type. 



Dimensions of the Skull. — The actual length of the various diameters is of much less 

 importance than their relations to one another in the science of craniolog\- ; they may, however, 

 be important in medico-legal questions. With the exception of the height, they vary within 

 wide limits, even among Caucasians. In the following table the means of both sexes are from 

 Broca : 



Males. Females. 



Mean. Millimetres. Millimetres. 



Length 182 174 



Breadth 145 135 



Height 132 125 



