A variation that occurs in the manubrium sterni of higher primates / by Arthur Keith.

  • Keith, Arthur, Sir, 1866-1955.
Date:
[1896]
Catalogue details

Licence: Public Domain Mark

Credit: A variation that occurs in the manubrium sterni of higher primates / by Arthur Keith. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    A VAEIATION THE MANUBRIUM STERNI OF HIGH^a^^S»^fl^TES. By Arthur Keith, M.D., F.E.C.S., Senior Demonstrator of Anatomy, London Hospital Medical College. Meckel (1), Shepherd (2), Arbuthnot Lane (3), Turner (4), Dwight (5), and Paterson (6), have drawn attention to a variation that occurs in the form of the manuh'ium sterni of men and apes. The variation consists in the enlargement of the manu- hmum or prestemum by the addition of the first meso-sternal segment. Stated in other words, instead of the joint in the sternmn opposite the insertion of the second costal cartilages persisting, as in the ordinary human form (Type L, in the annexed table), the joint opposite the third costal cartilages persists, as is nearly always the case in Gibbons—the hylobatian form (Type III.). In yoimg adults an intermediate form occurs, in which the joint opposite the third pair of cartilages is much wider than that opposite the second pair (Type II.). In the fully adult stage of such individuals, the manubrium sterni becomes of the hylobatian form. In very rare cases, only the joint opposite the fourth pair of cartilages persists (Type IV.). At late stages of life all the joints of the human sternum may be obliterated; this may happen at earlier stages of life in Gorillas and Orangs (Type V.). The prevalence of these various types of manubrium sterni is given in the annexed table. The percentage with which this variation appears in Man is almost impossible to estimate—probably about 1 per 1000. It is of much interest to note,'however, that at least three out of the nine cases recorded were found in dark-sMnned people. It occurs amongst Gorillas at about 20 per cent.; Chimpanzees, 30 per cent.; Orangs, 1 per cent.; and in Gibbons about 80 per cent. It is a variation common to the higher Primates, but occurs with widely varying frequency in the different groups.