The Probert Encyclopaedia of Medicine

EYELID

The eyelids are two folds of skin that shield the eyeball. The upper lid is larger and more movable. It regulates the opening and closing of the eye with the help of the orbicularis palpebrarum muscle. Lower-lid movement is slight. The eyelids sweep dirt from the surface of the eye, protect it from injury, and help distribute the tear fluid. When the eye is closed, the lids unite at the lid-slit in a downward curve. The corners of the eye are called the inner canthus, which is near the opening of the lachrymal duct, and the outer canthus, which ends in the crease where the upper lid overlaps the lower lid. The eyelid is lined with a mucous membrane called the conjunctiva. This lining also covers the front of the eyeball. This covering, when washed with tears, gives the eye its glossy appearance.
Research Eyelid