ANATOMY

Detailed explanation-1: -The risorius muscle’s function is to aid in facial expression by pulling the corner of the mouth laterally via its contraction in an outward and upward motion. In conjunction with other facial muscles, this helps to create a smile or a frown, and myriad other expressions in-between.

Detailed explanation-2: -The depressor anguli oris (triangularis) is also associated with the corners of the mouth. Located opposite to the levator anguli oris, it pulls the corners of the mouth downward, producing a frown.

Detailed explanation-3: -Risorius, which is located on each side of your mouth and aids in smiling. Zygomaticus major and minor, which allow you to smile.

Detailed explanation-4: -The innervation of the risorius stems from the buccal branch of facial nerve (CN VII), and vascularized by the superior labial branch of the facial artery. The risorius is deemed as the “smiling muscle” since its main function involves pulling the angles of the mouth laterally and superiorly to produce a smile.

Detailed explanation-5: -Two muscles can lift the corner of the mouth: the Musculus zygomaticus major and the Musculus levator anguli oris. In contrast, the lowering of the corner of the mouth is controlled by the muscle depressor anguli oris and the platysma.