Hippos are some of the earth’s largest land animals. Their name derives from Greek when they were called “river horses,” although “river cows” might have been a better description. These ferocious ...

The ability to open so wide is allowed by a rear-located jaw and a folding orbicularis oris muscle that can fold open and closed when needed. Hippo skulls are massive, reflecting the animal that they ...

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 ...