146 



SPECIAL ANATOMY OF THE SKELETON 



Occipital Point. The point in the middle line of the occipital bone farthest from the glabella. 



Inion. The external occipital protuberance. 



Opisthion. The mid-point of the posterior margin of the foramen magnum. 



Basion. The mid-point of the anterior margin of the foramen magnum. 



The Points on Either Side of the Mesal Plane are: 



Gonion. The outer margin of the angle of the mandible. 



Dacryon. The point of union of the antero-superior angle of the lacrimal with the frontal 

 bone and the frontal process of the maxilla. 



Stephanion. The point where the temporal line intersects the coronal suture. 



Pterion The point where the greater wing of the sphenoid joins the antero-inferior angle 

 of the parietal. 



A uricular Point. The centre of the orifice of the external auditory meatus. 



Astcrion. The point of meeting of the lambdoid, masto-occipital, and mastoparietal sutures. 



FIG. 114. Brachycephalic cranium, 

 and Charpy.) 



(Poirier 



FIG. 115. Dolichocephalic cranium 

 and Charpy.) 



(Poirier 



FIG. 116. Brachycephalic cranium, 

 and Charpy.) 



(Poirier 



Fie. 117. Dolichocephalic cranium, 

 and Charpy.) 



(Poirier 



The horizontal circumference of the cranium is measured in a plane passing through the 

 glabella (Turner) or the ophryon (Flower) in front, and the occipital point behind; it averages 

 about twenty inches (50 cm.) in the female and twenty-one inches (52.5 cm.) in the male. 



The occipitofrontal or longitudinal arc is measured from the nasion over the middle line of the 

 vertex to the opisthion; while the basinasal length is the distance between the basion and the 

 nasion. These two measurements, plus the antero-posterior diameter of the foramen magnum, 

 represent the vertical circumference of the cranium. 



The length is measured from the glabella to the occipital point, while the breadth, or greatest 

 transverse diameter, is usually found near the external auditory meatus. The proportion of 



, (breadth X 100) . 

 breadth to length j -T- is termed the cephalic index, or index of breadth. 



