The muscle of the lower corner of the mouth (lat. musculus angulus oris inferioris) is a group of muscles that are located in the lower part of the mouth and are responsible for the movement of the corner of the mouth. It consists of three main muscles - the angular upper lip (lat. m. levator labii superioris alaeque nasi), the nasal medial pterygonasal muscle (m. nasalotubalis medialis) and the medial pterygoid muscle (lat. M. pterygoideus medius).
The muscle of the inferior angle of the mouth is the most important muscle responsible for opening the mouth. It helps while talking or eating