It is widely accepted that all dentists should have a thorough understanding of the muscles involved in moving or stabilizing the mandible. However, there is still much discussion regarding the influence of the mandibular muscles on normal facial growth and dental development, as well as on orthodontic treatment and post-treatment stability. Potential patients with different underlying vertical muscle patterns will have differences in the expected directions of future mandibular growth, lateral profile shape, facial and arch widths and vertical occlusal relationships. In turn, thorough diagnoses are likely to lead to differences in individual aims and objectives, treatment plans, timing of commencement, mechanical design, lateral profile and smile-aesthetics outcomes, choice of retention and plans for long-term maintenance. The potential influence of the mandibular muscles on normal morphologic variation and the soft tissue implications on contemporary orthodontic treatment and stability will be addressed in this review.