Dogs seem to smile thanks to fibers in muscles in their face. The fibers are different from those of their gray wolf distant cousins, which don't make similar expressions.

Your orbicularis oris is sometimes known as the kissing muscle. It is a circular muscle that closes your mouth and puckers your lips when it contracts. Back to top. Human body homepage ...

Purpose To establish an objective parameter (orbicularis function) to measure the efficacy of botulinum toxin treatment in weakening the orbicularis of blepharospasm and hemifacial spasm sufferers.