PECTORALIS MAJOR AND DELTOID INSERTION 



169 



of the deltoid is accordingly the most constant of the points of 

 muscle insertion which have been used, and can be located with 

 considerable precision near the middle point of the humerus. 

 Actually, this point lies slightly below the middle of the length 

 of the humerus in whites, slightly above in negroes; a racial dif- 

 ference which is represented by the average difference of 0.73 of 

 the averages of the index. In the female the most distal point 

 of the deltoid is situated somewhat more proximal than in the 

 male. It is also of interest to note, that the distal end point of 

 the deltoid insertion, similarly to the middle point, is located on 

 the average noticeably more distally on the left side than on the 



TABLE 8 



Absolute and relative numbers of individuals with symmetrical and asymmetrical 



position of the most distal point of insertion of the deltoid and averages 



of the individual differences of the position index 



right. Table 8 gives a view of the absolute and relative number 

 of individuals with equal and unequal indices of position for the 

 most distal point of the deltoid insertion and also the average 

 differences of the unequal indices. It shows that the point re- 

 ferred to occupies the same relative position on both sides in a 

 total of only three cases; furthermore that the point was in a 

 greater number of instances more distally situated on the left 

 side, and that the differences in favor of the left always exceeded 

 on the average those of the right. The greatest individual 

 difference of the index appears in a white male with 6.4 in iavor 

 of the left side. 



The exact determination of the position of the insertion of the 

 pectoralis major and deltoid muscles on the humerus shows, 



