The human masseter muscle and its biological correlates: A review of published data pertinent to face prediction

The masseter muscle forms a cornerstone of anatomical facial reconstruction (FR) methods, yet it is only scantily described in the FR literature despite relatively intense research focus from other disciplines. This suggests that much more data exists for masseter prediction than that which is currently used in FR. This paper reviews the masseter muscle and finds that highly pertinent anatomical and metric data to be available despite being overlooked in the FR literature. This includes variance and means of the perimeter dimensions, thicknesses, cross-sectional areas, volumes, metrics associated with muscle attachment, and correlations with other biological and craniometric variables (such as sex, age, tooth loss, cranial breadths, facial heights, alveolar thicknesses, and gonial angles). The oversight of these metric data adds to a general pattern seen for other hallmark structures of the face in FR and, taken together, these observations hold major ramifications for longstanding debates of FR accuracy, reliability, and error. Irrespectively, the data reviewed in this manuscript help set an improved basis for quantification of FR techniques.