Your professor says something profoundly funny. you are tempted to laugh but because you failed to brush your teeth this morning all you can do is to manage a closed-mouth smile. what muscle are you primarily using?

Explanation:

The Muscles Used To Smile Are:

Zygomaticus major and minor : These muscles pull up the corners of your mouth. There is one set on both sides of the face. MINOR  originates from zygomatic bone and continues with orbicularis oculi on the lateral face of the levator labii superioris and then inserts into the outer part of  the upper lip. MAJOR draws the angle of the mouth superiorly and posteriorly to allow one to smile.Orbicularis oculi: Causes the eye crinkle. It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a short fibrous band, the medial palpebral ligament.Levator labii superioris: Pulls up the corner of lip and nose. It is a broad sheet, the origin of which extends from the side of the nose to the zygomatic bone.Levator anguli oris:  Is a facial muscle of the mouth arising from the canine fossa, immediately below the infraorbital foramen. It elevates angle of mouth medially. Its fibers are inserted into the angle of the mouth, intermingling with those of the zygomaticus, triangularis, and orbicularis oris.Risorius:  Is a muscle of facial expression which arises in the fascia over the parotid gland and, passing horizontally forward, superficial to the platysma, inserts onto the skin at the angle of the mouth. It is a narrow bundle of fibers, broadest at its origin, but varies much in its size and form. It pulls the corners of mouth to the side of the face.

Lacking something of the ozone layer