118 



LABORATORY MANUAL OF ANTHROPOMETRY 



for measurements 8 and 9 consists of two graded scales , set at right arigles 

 to each other. One spans the bone in the. median line, and is placed in 

 contact at the promontorium and the apex, while the other, which slides 

 upon the first, and also lengthens and shortens, is adjusted as desired. 

 When in the position cd its length, and its position on the base line, can 

 be read off on the scales.* 



10. Antero-posterior (sagittal) diameter of the anterior articular surface', 

 the surface that articulates with the last lumbar vertebra. SC or TM 



11. Lateral (transverse) diameter of the same. Nos 10 and 11 must 

 be at right angles to each other. SC or TM 



II. INDICES 



(a) Sacral indices; designed to show the general shape of the bone as a 



whole. 



I. Sacral index A (4 : 2) 



anterior straight breadth X 100 



mid-ventral straight length 



1N anterior straight breadth X 100 

 2. Sacral index B (4 : 1) - 7-5 



mid-ventral curved length 



, N anterior curved breadth X 100 

 Sacral index' c (3:1)- =-^ 



mid-ventral curved length 



Of the above three indices A is the classical one used by Turner; 

 while B and C have the merit of expressing the full value of the vertebral 

 axis, but have thus far been but little used. In these indices the sexual 

 difference is marked, the breadth measures, and consequently the indices, 

 being greater in females, f 



The following values of Sacral index, A, have been found for various 

 races, and appear here. as compiled by Radlauer. 



RACAL INDICES SACRAL INDEX A 



* This instrument was devised by RADLAUER and is figured by him in the article 

 above cited (p. 336). 



t With the exception of the ossa coxae (innominata; there is no bone in the body 

 more profoundly modified by sex than is the sacrum. The sex should thus be con- 

 stantly regarded in all general averages, especially those which concern breadth of 

 the bones, or the depth of curvature, and in conclusions connected with racial char- 

 acteristics. Cf. DERRY: The influence of sex on the position and composition of the 

 Human Sacrum, in Journ. Anat and Physiol. (Engl.), 1912, pp. 184-192. 



