9 Grammatical Pitfalls
platysma pla·tys·ma (plə-tĭz'mə)
n. pl. pla·tys·mas or pla·tys·ma·ta (-mə-tə)
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.