In man the main function of the facial nerve is motor, for emotional facial expression. The nerve has, however, four other functions—taste, in the anterior two thirds of the tongue; secretory, for saliva and tears, and deep visceral sensibility, especially of the soft palate.1 The latter functions, which are minor in man, are of great importance in the lower animals for obtaining food. In these animals the facial nerve is well developed, though fishes, amphibia, reptiles and birds are all devoid of emotional facial expression, as if wearing an immobile mask. Their only facial movement is that of closing the eyes.
Facial movement developed in the mammalia and especially in the primates. In man the motor function has developed to overwhelming importance. By facial emotional expression ideas are conveyed in a universal language. Man illustrates speech and moods and uses expression as a means of communication. It orients the listener,
BUNNELL S. SURGICAL REPAIR OF THE FACIAL NERVE. Arch Otolaryngol. 1937;25(3):235–259. doi:10.1001/archotol.1937.00650010273001
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