Comparative anatomy of cutaneous muscles of the face.

Comparative anatomical studies of monkeys, apes, and humans have clarified essential factors involved in the structure of the cutaneous muscles of the face. Among the findings are that the platysma muscle is a very important entity because it is the only muscle without any bony attachments. In addition, the platysma is a fan-shaped structure that has been divided artificially by classical anatomists into five elements. The parotid fascia forms part of this fan-shaped fibromuscular structure and is not of the deep fascia. As such, these findings require a revision of the classical anatomical concepts of the parotid space.