In a previous chapter we have seen that with animals the hairs are
erected by the contraction of minute, unstriped, and involuntary
muscles, which run to each separate follicle. In addition to this
action, Mr. J. Wood has clearly ascertained by experiment, as he
informs me, that with man the hairs on the front of the head which
slope forwards, and those on the back which slope backwards, are raised
in opposite directions by the contraction of the occipito-frontalis or
scalp muscle. So that this muscle seems to aid in the erection of the
hairs on the head of man in the same manner as the homologous
_panniculus carnosus_ aids, or takes the greater part, in the erection
of the spines on the backs of some of the lower animals.
_Contraction of the platysma myoides muscle_. This muscle is spread
over the sides of the neck, extending downwards to a little beneath the
collar-bones, and upwards to the lower part of the cheeks. A portion,
called the risorius, is represented in the woodcut (M) fig. 2. The
contraction of this muscle draws the corners of the mouth and the lower
parts of the checks downwards and backwards. It produces at the same
time divergent, longitudinal, prominent ridges on the sides of the neck
in the young; and, in old thin persons, fine transverse wrinkles. This
muscle is sometimes said not to be under the control of the will; but
almost every one, if told to draw the corners of his mouth backwards
and downwards with great force, brings it into action. I have, however,
heard of a man who can voluntarily act on it only on one side of his
neck.
Sir C. Bell[1221] and others have stated that this muscle is strongly
contracted under the influence of fear; and Duchenne insists so
strongly on its importance in the expression of this emotion, that he
calls it the _muscle of fright_.[1222] He admits, however, that its
contraction is quite inexpressive unless associated with widely open
eyes and mouth. He has given a photograph (copied and reduced in the
accompanying woodcut) of the same old man as on former occasions, with
his eyebrows strongly raised, his mouth opened, and the platysma
contracted, all by means of galvanism. The original photograph was
shown to twenty-four persons, and they were separately asked, without
any explanation being given, what expression was intended: twenty
instantly answered, intense fright or horror ; three said pain, and
one extreme discomfort. Dr. Duchenne has given another photograph of
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