Laughing muscles
As laughter muscles applies to those facial muscles , which the characteristic facial expressions of laughter or smiles produce. Mainly these are the zygomaticus major muscle , which pulls the corners of the mouth upwards from the zygomatic arch , and the deeper risorius muscle - a flat, thin muscle cuff that runs from the lower cheek area across the corner of the mouth and actually an integral part of the broad neck muscle represents.
Depending on the type and strength of the joyful expression, both muscles (and others) are stressed differently. The laughing muscles are innervated by the facial nerve , the seventh cranial nerve, which also supplies all other facial muscles .