Eyelids

The eyelids protect the eyes from the environment, injury and light.  They also maintain a smooth corneal surface by spreading tears evenly over the eye.  The lids are composed of an outer layer of skin, a middle layer of muscle and tissue that gives them form, and an inner layer of moist conjunctival tissue.

Several muscles work together to control the  actions of the lids.  Located in the middle layer of the eyelid is the orbicularis oculi, a circular muscle that closes the lids.  The levator muscle is attached inside the upper lid and elevates it.  A smooth muscle called Mueller's gives the lids tone and helps maintain elasticity.

Tiny oil-producing meibomian glands line the inner edge of the lids.  These glands produce oil that lubricates the eye.  Rows of lashes protect the eyes from the elements and debris. 

Not only do the eyelids provide protection and moisture, they display expression and emotions that are an important part of our individuality.