Which muscle is involved in the drawing down or side movement of the lower lip?

The muscle responsible for drawing down or side movement of the lower lip is the quadratus labii inferioris. This muscle plays a crucial role in facial expressions, particularly in actions that involve moving the lower lip downwards or laterally. It is located at the sides of the mouth and contributes to expressions of sadness or frowning, as well as other movements such as pouting.

Understanding the functions of facial muscles is essential for estheticians, as they often perform services that involve the lower face. The quadratus labii inferioris specifically allows for subtle movements that affect the appearance and expressiveness of the lips.

The other muscles listed do not perform this function. The corrugator muscle is primarily involved in frowning by drawing the eyebrows downward and together. The procerus muscle contributes to the movement of the forehead and the eyebrows, playing a role in expressions of disdain or anger. The levator palpebrae superioris is responsible for elevating the upper eyelid, which is unrelated to lip movement.