ABSTRACT
The orbicularis oculi is a ring-shaped muscle that lies immediately under the skin in the periorbital zone. It is composed of three parts: the preorbital (the most external), preseptal, and pretarsal (closest to the eyelashes) portions (Figure 16.1). Repeated contraction of the lateral parts of the preseptal and preorbital portions of the orbicularis muscle causes the formation of ‘crow’s feet’ or ‘smile lines’, wrinkles extending radially from the region of the lateral canthus (Figure 16.2).1
