38 THE HUMAN STERNUM 



The male metasternum, therefore, appears to be shorter and broader ; the 

 female longer and narrower. 



The male sternum thus differs from the female in having a longer 

 and narrower mesosternum, and a presternum (and possibly a metasternum) 

 which are shorter and broader. 



Relative length of Presternum and Mesosternum in the Male and Female 



The law propounded by Hyrtl^* is not obeyed by the series under 

 examination (Table XIII), that ^ the manubrium of the female sternum exceeds 

 half the length of the body ; while the body in the male sternum is at least twice as 

 long as the manubrium.^ This law was supported by Strauch,*^ quoted by 

 DwiGHT ; but has been somewhat adversely criticized by the last-named 

 author." An analysis of the lengths of the presternum and mesosternum 

 in the adult (22-82) shows that on the average the relative length of the two 

 parts is the same in both sexes (i : 1-9), and the presternum is thus usually a 

 little more than half the length of the mesosternum. 



When, however, the series of adult sterna is broken into two groups 

 — those under and those over forty years of age — a difference in relative 

 length comes to light, due probably to an increase in length in the male 

 mesosternum in later years. Between the ages of twenty-two and thirty-nine 

 (Table XIII), the relative length of the presternum and mesosternum is as 

 stated above (i : i'9) ; but between forty and eighty- two years, there is a 

 difference. The mesosternum of the male is twice the length of the pre- 

 sternum (i : 2) ; that of the female is less than twice the length (i : i"8); 

 so that the older group coincides with Hyrtl's statement. 



The measurements of one hundred and six young sterna (sixty-five 

 male, forty-one female), between two and twenty-one years, have been added in 

 Table XIII. The shrinkage of cartilage, and the consequent loss of length, 

 more particularly of the mesosternum, probably renders these measurements 

 fallacious ; but the series agrees with Hyrtl's statement, the relative length 

 of presternum and mesosternum being in the male i : 2, and in the female 

 I : 1-9. 



