_On the depression of the corners of the mouth_.--This action is
effected by the _depressores anguili oris_ (see letter K in figs.
1 and 2). The fibres of this muscle diverge downwards, with the upper
convergent ends attached round the angles of the mouth, and to
the lower lip a little way within the angles.[6] Some of the fibres
appear to be antagonistic to the great zygomatic muscle, and others
to the several muscles running to the outer part of the upper lip.
The contraction of this muscle draws downwards and outwards the corners
of the mouth, including the outer part of the upper lip, and even in
a slight degree the wings of the nostrils. When the mouth is closed
and this muscle acts, the commissure or line of junction of the two
lips forms a curved line with the concavity downwards,[7] and the lips
themselves are generally somewhat protruded, especially the lower one.
The mouth in this state is well represented in the two photographs
(Plate II., figs. 6 and 7) by Mr. Rejlander. The upper boy (fig. 6)
had just stopped crying, after receiving a slap on the face from another boy;
and the right moment was seized for photographing him.
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