Title: The American Museum journal
Identifier: americanmuseumjo17amer (find matches)
Year: c1900-(1918) (c190s)
Authors: American Museum of Natural History
Subjects: Natural history
Publisher: New York : American Museum of Natural History
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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EVOLUTIOX OF THE HUMAN FACE 383 fact p'ives tlic eluu^ to tliu origin <»l' tlu' facial muscles. In the remote ancestors of the mammals only the ))latysma and the immediately nnderlying sphincter colli muscles were present; it is highly prol)ahle that this sheet of nerve tissue gradually spread froui the under side of the throat upward and foi-ward ' Tlieory put forth by Ruge. Tliis is generally accepted by anatomists as the true explanation of the origin of the facial muscles of mammals. along the sides of the face, hy degrees creeping over the old bony mask and beneath the skin, carrying with it the seventh nerve, and dividing and sub- dividing into numerous branches and layers; at the same time the nerve branched and branched again, as nerves have frequently been known to do when muscles became subdivided. Several analogous cases of the spread of a mus- cle laver into a new region are known
Text Appearing After Image:
The photograph shows the tense lips of a trained chimpanzee \\\, i- i;, ihe act of threading a needle. The action of the muscles of the human face is coordinated (especially in the child) with that of various other muscles of the body, and the same is noticeable in apes, which use the facial muscles much as we do but often with rather more empliasis than is usual in polite society. Courtesy of Professor W. T. Shep- herd, of Washington, D. C.

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