GESTURES NERVES OF THE FACE. 499 



by the pressure of a tumour beneath the ear: the orbicularis palpebrarum 

 was paralysed so that the patient was unable to close his eyelids. 



Independently of the various muscular actions which modify the 

 expression of the human countenance, there are certain others that 

 mark the different mental emotions. The skin varies in colour, be- 

 coming pale or suffused, and frequently alternating rapidly between 

 these two conditions. The changes are more especially witnessed on 

 the forehead, cheeks, and lips ; and arise from an augmented or dimi- 

 nished flow of blood into the capillaries of the part, under the influence 

 of the existing emotion. Under such circumstances, the eye may par- 

 ticipate in the suffusion. The skin may, also, vary in its degree of 

 moisture or heat; it may be dry, or bathed in perspiration; and the 

 perspiration may be warm or cold ; the two conditions occasionally 

 alternating. Particular parts of the face, again, are more susceptible 

 of this "sweat of expression," as it has been termed, the forehead and 

 temples for example. The heat of the head is also occasionally modi- 

 fied; a sudden glow is felt in the countenance; and the expression 

 is sometimes evident to a second person. 



The expression of the human eye, connected with the action of the 

 oblique muscles, has been referred to under Vision. It was there 

 asserted, that in insensibility, the organ, it has been presumed, is given 

 up to the action of the oblique muscles, and is drawn up under the 

 upper eyelid. The eye itself is, however, capable of various expres- 

 sions, depending upon varied positions of its tutamina; and especially 

 of the secretion from its mucous covering the conjunctiva, and from 

 the lachrymal gland; so that it may be swimming, or the tears may 

 flow over the cheeks and constitute weeping. 



In addition to these, which may be esteemed sources of expression 

 in the human countenance, may be added the action of osculation or 

 kissing ; which, wherever practiced, is employed as an expression of 

 love and friendship ; confined with us to those of the female sex, or 

 of opposite sexes ; but, in some countries, employed as an expression of 

 regard between males also. 



It is impracticable to describe all the facial expressions JProso- 

 posis, as they have been collectively termed of which the human 

 countenance is susceptible. They are commonly classed under two 

 heads; the exhilarating, in which the face is flushed, and the counte- 

 nance expanded; the muscles being contracted from within to without; 

 and the depressing, in which, on the contrary, the face is pale, and the 

 features are drawn inwards and sunken. 



Let us inquire into the physiology of a few of these expressions; 

 beginning with the play of the features in broad laughter, (Fig. 205,) 

 as being, perhaps, the most easy of explanation. In laughing, it is 

 in vain that we endeavour to confine the lips; a complete relaxation of 

 the orbicularis oris gives uncontrolled power to the opponent muscles 

 inserted into the angles of the mouth and upper lip. Hence, the late- 

 ral retraction of the angles of the mouth; the elevation of the upper 

 lip disclosing the teeth; the peculiar elevation of the nostrils without 

 their being expanded, and the dimple of the cheek, where the acting 

 muscles congregate: hence, also, the fulness of the cheeks, rising so as 



