230 



HUMAN ANATOMY. 



Cranial Capacity. — This may vary in all races from looo to 1800 cubic centimetres. 

 Welcker gives the following means and extremes for white races : ' 



Mean. Maximum. Minimum. 



, Cu. cm. Cu. cm. Cu. cm. 



Males 1450 1790 1220 



Females 1300 1550 1090 



A skull with a capacity e.xceeding 1450 cubic centimetres is megacephalic ; one with a 

 capacity from 1350 to 1450, mesocephalic ; one below 1350, viicf-ocephalic. 



Manouvrier has devised a formula for calculating the weight of the brain from the cranial 

 capacity, as follows : weight in grammes is to capacity in cubic centimetres as i to 0.87. 



Asymmetry. — The whole head is almost always asymmetrical. The left side of the 

 cranium, as shown by hatters' models, is larger, especially in the frontal region. The right 

 side of the head is usually the higher. The cause of this is probably to be found in habitual 

 position. The spine is not held symmetrically, but the atlas inclines to the left ; the head, when 

 held most firmly, does not rest evenly on both condyles, but on one, usually the left. The 

 position of the head, thus taken, is not enough to compensate for the obliquity of the base ; but 

 certain changes take place in the relations of the component parts. Thus a face which seems 



Fig. 260. 



Anterior fontanelle 



Anterior lateral 

 fontanelle 



The skull at birth, from before. 



tolerably symmetrical when resting on the left condyle only becomes quite uneven if placed 

 upon both. The right orbit is usually the higher, the right side of the jaw is the stronger, and 

 its teeth are set in a smaller curve. The tip of the nose "turns to the right. Moreover, the face 

 lacks symmetry in another direction : the right upper jaw and the malar bone are more promi- 

 nent than the left. More striking differences, depending on these, are seen during life, which 

 are ascribed to the effect of gravity on soft parts habitually held une\'enly, the right side being 

 the higher. The right eye is the higher and, apparently, the larger, the lids being'farther apart ; 

 while the cleft is narrow on the left and the eye nearer the nose. The left nostril is the larger ; 

 the left fold of the cheek is less marked. In a certain proportion of persons all these peculiarities 

 are reversed, and some of them may be transposed without the others. 



Growth and Age of the Skull.— By the sixth month of foetal life the skull, though smaller, is 

 in much the same condition as at birth, except that then the occipital region is relatively larger. 

 The tnost striking points are the insignificance of the face and the flatness of the inferior surface. 

 In the cranium the frontal region is relatively small. The \ault, which is de\eloped in mem- 

 brane, presents marked prominences at the parietal and frontal eminences, and a smaller one at 



' Extreme cases occasionally pass these limits. There is in the Warren Museum the skull 

 of a Highlander with a capacity of 1990 cubic centimetres, and one of a tall man, presumably an 

 American, who could read and write, though his intelligence was defective, with a capacity of 

 1225 cubic centimetres. Turner has noted the skull of a female Australian of 930 cubic centi- 

 metres' capacity. 



