While we have tried to limit the number of muscles of facial expression in this lesson to the ones most important to the oral practitioner there are a couple of other muscles that are important even if they have no effect on the oral cavity. The first of these is the orbicularis oculi. While this muscle shares a first name with the orbicularis oris it is a much simpler muscle in form. It has an origin and insertion at the medial corner of the eye so acts like a sphincter squeezing the eye shut. It does have two parts though as the muscle in the eyelids are considered part of this muscle in addition to the circular fibers that surround the eye.