The facial mimetic muscles have a roughly one to one nerve to muscle fiber innervation, making them highly responsive to stimulation, capable of great flexibility in motion, and allows correlation with speech and emotion. As such, the facial mimetic musculature is amongst the most heavily used group of muscles in the body. However, the facial mimetic muscles are not designed to be load bearing unlike the masticatory muscles (temporalis, masseter, pterygoids), which tend to enlarge with heavy use. Body builders will frequently have more prominent temporalis and masseter muscles combined with relative loss of facial fat. The loss of facial fat leads to a general hollowness in the mid-facial area, which is less desirable esthetically than loss of fat in other areas of the body