Which muscle is primarily responsible for the development of crow's feet at the eye?

The muscle primarily responsible for the development of crow's feet around the eye is the orbicularis oculi. This muscle encircles the eye and is engaged when closing the eyes, smiling, or squinting. Over time, repetitive contractions of the orbicularis oculi, particularly with facial expressions such as smiling or laughing, can lead to the formation of dynamic wrinkles or lines at the lateral canthus of the eyes, commonly referred to as crow's feet.

In contrast, while the frontalis muscle is involved in raising the eyebrows and can contribute to forehead wrinkles, its actions do not directly cause crow's feet. The corrugator supercilii assists in frowning and creating vertical furrows between the eyebrows, which does not relate to the lateral eye area. The procerus muscle, located between the eyebrows, is responsible for frowning and the formation of horizontal lines across the bridge of the nose. Each of these muscles has distinct functions, but none contribute to the crow's feet as effectively as the orbicularis oculi does.