platysma

(anatomy) A subcutaneous muscle of the neck, extending from the face to the clavicle; muscle of facial expression.

A platelike muscle in the neck extending to the lower face with origin from the subcutaneous layer and fascia covering the greater pectoral and deltoid muscles at the level of the first or second rib, with insertion to the mandible, the risorius muscle and platysma of the opposite side, with nerve supply from a branch of the facial nerve, and whose action depresses the lower lip and wrinkles the skin of the neck and the upper chest.

The superficial sheet of cutaneous muscle over the face and neck.

The noun has one meaning:

Meaning #1: either of two broad muscles located on either side of the neck and innervated by the facial nerve; extends from lower jaw to clavicle and is involved in moving the mouth and jaw