innerbody
Diagram

Platysma Muscle

The platysma muscle is a broad sheet of muscle arising from the pectoral (chest) and deltoid (shoulder) muscles and rises over the collarbone (clavicle), proceeding upward in a slanting manner along the sides of the neck. The muscle draws the lower lip and corner of the mouth sideways and down, partially opening the mouth, as in an expression of surprise or fright. When all the fibers work to their Continue Scrolling To Read More Below...