THE STERNUM AS AN INDEX OF SEX AND AGE.By THOMAS DWIGHT, M.D., Boston, U.S.A., Instructor inTopographical Anatomy and in Histology at -HarvardUniversity.

IN an essay on the identification of the human skeleton,published in 1878, I called attention to Hyrtl's1 statementconcerning the sexual characters of the breast bone. He says-" I find the difference between the male and female sternumso clearly expressed by the proportion of the manubrium to thebody, that it is hardly possible to err in determining the sex.The manubrium of the female sternum exceeds half the lengthof the body, while the body in the male sternum is, at least,twice as long as the manubrium." I mentioned also Luschka's 2assertion, that " the body is usually twice as long as the manu-brium in woman, and two and one half times as long in man."I gave the results in the essay of the measurements of thesternum in six skeletons, of which the sex was well marked insix dead bodies, and in the life-size figures of median sectionsof the body in Braune's plates.

Although the mean of these measurements confirmed Hyrtl'slaw, precisely one-half of the specimens were exceptions to it.My observations, however, were too few to be conclusive, thoughthe number of instances in which Hyrtl's law did not applywas enough to shake confidence in it.

Since then, I have obtained measurements (taken by myself,except in some two or three instances) of the sternum of twenty-seven male and twenty-three female dead bodies. To these Ihave added the measurements from bodies, which I have alreadypublished, suppressing those from skeletons and plates.The following table accordingly gives the length in centi-

nietres of the manubrium and body of the sternum, in each ofthirty men and twenty-six women. An asterisk marks thecases that are in accordance with Hyrtl's law.

l Handbuch der topographischen Anatomic.2 Die Anatomic des Jenschceh.

3IR THOMAS DWIGHT.

MALE. FEMALE.

Manubrium. Body. Manubrium. Body.IRRRRRRRRRRRRRRRRRRRRRRRRRRR

4.4565.74-74.4554-14.74 14.43-645*15.45-44-74.54.44.54.44.44.34-35

9.38 8*

9.11*9.59.59.8*6 6*889-1*7.6*8'87.78-71049 6*9-6*8*99-2118-89.310-67.8*8.1*

4 67 8-94

Thus it appears that the manubrium of the male sternum isto the body as 49(-) is to 100, and that in the female themanubrium is to the body as 52(+) is to the 100. Hyrtl'slaw is thus confirmed for the mean sternum, but unfortunately,not for the individual one. It is to be noticed that it did notapply to twelve of the thirty men, or to fourteen of thetwenty-six women. It is certainly of no practical value, anddoes not justify the assertion that " it is hardly possible to errin determining the sex." Luschka also is quite in error.

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101112131415161718192021222324252627282930

Mean

56-35.34.95.76 94 74.454.464.75.75.5554.55-14.954.75.55.57-24.34.75-454.35

5-18

10 6*10.110'45 210.19.111P4*11.71*11.4*11I*119-8 *12*11*910*12.7*10.2*11.5*12.8*10*

10.112.5*11.3*9.314.4*1069.1

10 59

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THlE STERNUM AS AN INDEX OF SEX AND AGE. 3

II.Many of the statements concerning the age at which the

pieces of the sternum coalesce, are even more wild than thoseconcerning the sex. Mr Hutchinson gives the following ac-count of the matter in his classical article OD the thorax, in theCyclopedia of Anatomy and Physiology:-" The lowest or fifthpiece is joined to the fourth soon after puberty; the fourth andthird are united between twenty and thirty years of age, and thebody of the sternum is usually not completed by the junctionof the third piece to the second before thirty-five or fortyyears." He states also that it is only exceptionally, and latein life, that the first piece, i.e. the manubrium, joins the second,and that the appendix becomes united to the sternum from thefortieth to the fiftieth year, and even later.Gray and Holden give the same dates for the joining of the

pieces of the body, excepting that they make the fourth jointhe third between the twentieth and twenty-fifth years.

I am inclined to think that the above statements are adoptedfrom Beclard's views, and copied by one author after anotherwith slight modifications.

According to Wagstaffe, " the lower segments unite afterpuberty, the upper segments about twenty-five, the body andensiform in middle age, the body and manubrium in old age."In the eighth edition of Quain, a similar statement is made.

According to Sappey, the two lower pieces of the body uniteat from two to three years, sometimes later. He does not givethe dates of the union of the other pieces. As for the appendix,he says that its ossification is complete at from thirty to thirty-five or forty years, and that it unites with the body at fromfifty to sixty. Both Henle and Cruveilhier place the joiningof the first piece of the body with those below it, at fromtwenty to twenty-five years. Cruveilhier states further, thatthe appendix joins the body at from forty to fifty years, andsometimes later.

I regret very much that I did not begin to take notes of theages of the bodies examined till the series of measurements wasfar advanced, and then I was not always able to obtain definiteinformation. I cannot therefore give statistics of any value;but I feel justified in making a few general statements.

32)9

THE STERNUM AS AN INDEX OF SEX AND AGE.

One word as to what "codsified" means. It seems to me tomean that adjoining parts are so firmly connected by bone,that they cannot be separated without breaking or cutting it;but it is by no means necessary that the union should extendthrough the whole thickness. Thus the sacral vertebra, are saidto be cobsified, though a section would show spaces between thecentres of the bodies. This is mentioned because Cruveilhierspeaks of the union between the manubrium and the body beingusually only apparent because it is merely superficial. It seemsto me none the less real.My observations have convinced me that the accounts accord-

ing to which the body of the sternum is in three pieces tilltwenty or thirty, and in two till thirty-five or forty, are entirelywrong. I can remember but very few instances of persons oftwenty or over, in which the body of the sternum was not inone piece.

I can confirm the prevailing idea that the appendix is usuallyjoined to the body earlier than the manubrium is; and Ihave seen several instances that induce me to think thatthe appendix is often joined to the body earlier than isgenerally believed, There is no doubt, however, that thereis great variation, and that the sternum is a very uncertainbone. In illustration of this, I quote a few cases from mynotes.The appendix was united to the body in a woman of twenty-

two, a man of twenty-three, a male Western Islander of abouttwenty-eight. The process was beginning in a woman of fromthirty-two to thirty-five. The appendix was barely co6sifiedin a man of sixty or more. On the other hand, the processhad not begun in a woman of thirty-nine, or in another of fiftyor more. A man of about forty, presented commencing ossifi-cation between the body and the manubrium, but not betweenthe body and the appendix. Another man, looking at leastsixty-five, had the manubrium joined, and the appendix free.

It must be admitted that the breast bone is no trustworthyguide either to the sex or the age.

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