risorius

Risorius is a small muscle embedded with this capsules substance...

"Coupled with a depressing of the corners of the lips, using the risorius.

The Teeth position would cause the zygomaticus major or the risorius muscle, resulting in a smile.

The risorius retracts the angle of the mouth to produce a smile, albeit an insincere-looking one that does not involve the skin around the eyes.

She's making a nasty face, her risorius muscles cinching her face tight around her nose while she dries her hands on her dark skirt.

Like all muscles of facial expression, the risorius is innervated by the facial nerve (CN VII).

After that, you can tell a fake smile because the risorius and platysma muscles pull the lower lip down and out, squaring it and exposing the lower teeth.

In its course over the face, it is covered by the integument, the fat of the cheek, and, near the angle of the mouth, by the platysma, risorius, and zygomaticus major.

The 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 contributed to by the following muscles: orbicularis oris, buccinator, levator anguli oris, depressor anguli oris, zygomaticus major, risorius, platysma, levator labii superioris.

He was studying teasing in American fraternity houses and found that low-status frat members, when they were teased, smiled using the risorius muscle - a facial muscle that pulls the lips sideways - as well as the zygomatic major, which lifts up the lips.

It has been suggested that the risorius is only found in humans: "Among the hominoids dissected for the present study, only modern humans had a well-defined, separate, risorius" and in chimpanzees potentially similar fibers "did not form a distinct, well defined muscle risorius such as that found in most humans".