medical Definition of platysma
plural platysmata
play
\-mət-ə\
also platysmas
: a broad thin layer of muscle that is situated on each side of the neck immediately under the superficial fascia belonging to the group of facial muscles, that is innervated by the facial nerve, and that draws the lower lip and the corner of the mouth to the side and down and when moved forcefully expands the neck and draws its skin upward
