Question

multiple choice question the muscle of facial expression indicated in the image by the letter a is the levator labii superioris risorius platysma zygomaticus major

Explanation:

The zygomaticus major is a prominent facial - expression muscle that extends from the zygomatic bone to the corner of the mouth and is responsible for smiling. By comparing the location of the muscle labeled A in the image with the known locations of the listed muscles, we can identify it as the zygomaticus major. The levator labii superioris is above the upper lip, the risorius is more lateral near the ear - to - mouth line, and the platysma is a neck muscle.

Answer:

zygomaticus major