OSTEOMETRY; THE MEASUREMENT OF THE BONES 55 



37. Maxillary breadth; between the two zygomaxillary sutures, at 

 their lowest external point (zm-zm). 



38. Greatest occipital breadth; the distance between the two asteria 

 (ast-asfc). This measures the greatest breadth of the occipital bone 

 along its lateral sutures, and corresponds to the measurement of the 

 greatest frontal breadth (No. 6). SC. 



39. Frontal arc; the distance nasion-bregma, over the surface. TM. 



40. Parietal arc; the distance bregma-lambda, over the surface. TM. 



41. Occipital arc; the distance lambda- opisthion, over the surface. 

 TM. 



These three last, 39, 40, and 41, added together, should equal the 

 measure of the total cranial arc, No. 22. The exact points used for 

 bregma and lambda may be marked by a pencil line, to insure the use of 

 the same point for two consecutive arcs, or the judgment may be put 

 to a severer test by measuring each arc by itself, without reference to 

 the rest. In a well-marked skull it will be found that these measures, 

 however taken, will correspond within a millimeter or two. 



42. Frontal chord; the distance nasion-bregma, in a straight line, as 

 measured by the slide compass. SC. 



43. Parietal chord; the distance bregma-lambda, in a straight line, 

 as measured by the slide compass. SC. 



44. Occipital chord; the distance lambda-opisthion, in a straight line, 

 as measured by the slide compass. SC. 



These last three measures, 42, 43, and 44, may be also measured upon 

 the diagraph tracing of the median sagittal curve, and if the two methods 

 are correctly used, the two should correspond. Certain other distances, 

 as basion-bregma, nasion-basion, etc., may be also measured upon the 

 diagraph curve, and a comparison of the two methods will prove each 

 other. Aside from a number of important angles, the craniogram 

 furnishes much the best, or sometimes the only method of obtaining 

 certain other important linear measurements, such as the calvarial 

 height, the lambda calvarial height, and the bregma perpendicular. 

 These will be considered below, under the subject of the median sagittal 

 craniogram. 



45. Mandibular length; the distance between the anterior point of the 

 mandible and the median point of a line drawn across the posterior 

 surface of the two gonia. Place a knitting needle across the back of the 

 gonia, and measure from the middle point of this to the anterior limit 

 of the jaw, anterior surface, both in the median sagittal plane. 



MEASUREMENTS TO BE OBTAINED FROM THE MEDIAN SAGITTAL 



CRANIOGRAM 



Many of the above measurements of cranium and face may be taken 

 upon the median profile curve of a skull, when drawn accurately by 



