Why Does the Frontalis Muscle “Never Come Back”? Functional Organization of the Mimic Musculature

Abstract

The normal function of the forehead muscle after severe damage to the facial nerve, and especially after nerve reconstruction in the trunk region, cannot be regained. This striking phenomenon was described as early as in 1936 by Martin and in 1948 by Tickle [1,5]. Miehlke (1973), in his classical monograph [2] on the “Surgery of the Facial Nerve” summarized this fact as follows: “Every expert in the surgery of the facial nerve knows about the repeatedly mentioned experience that, after a lesion of the facial nerve, recovery of the frontal part of the occipito-frontal muscle is either incomplete or non-existent. This is almost the rule after neurotmesis… The peculiar behavior of this muscle is not yet explained”, and he continued: “One might be permitted to think that the frontal part of the occipito-frontal muscle has some special tendency toward atrophy and fibrosis” (p. 239).