Facial anatomy.

Botulinum toxin acts at the neuromuscular endplate, which requires precise delivery of the drug to achieve a desired clinical result. A thorough understanding of the complex anatomic structures of the face and their effect on facial form and function, coupled with an appreciation of facial esthetics and the balanced muscle actions that produce resting and active facial form, will result in accurate and reproducible clinical effects. Utilizing some general anatomic principles in combination with specific individual facial features and variations will enable the physician to consistently find the optimum injection sites and combination of other therapies for desired outcomes.