Your upper eyelid is attached to a muscle that allows it to move up and down to cover or reveal your eye. This is aided by a smaller, supporting muscle. A muscle behind the skin of your brow also helps to elevate your eyelids from above. These are all part of the complex system of muscles that control your face.
The simple muscle of your upper eyelid is called the levator palpebrae superioris (LPS). It's a small muscle located just below the skin of your upper eyelid. It works with the larger LPS to lift your eyelid when you open your eyes. The LPS runs along the side of your head, beneath your ear, and ends in your eyebrow.
If you look in a mirror and raise an eyebrow, you'll see how this small muscle lifts your eyelid. It does so by pulling on hair that has grown out from inside your skull, above your ear. This creates a tension within the muscle that causes it to contract. As it contracts, it pulls your eyelid up and back, covering your eye.
People don't often think about their eyelid muscles, but they do exist! They help us blink, watch television with our eyes closed, and even smile. The LPS is especially important because without it people would be unable to hide their emotions. The LPS is used in facial expressions such as crying and frowning.
A tiny flap of skin that covers and protects the eye is known as an eyelid. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outer world and so allowing vision. This might happen deliberately or involuntarily. Involuntary blinking is important for maintaining good vision because it removes dust and debris from between the lens and the retina.
The three main types of eyelids are: naked, hairy, and browed. Naked eyelids are only covered by skin and no hair or bone is present below the eye. Hairy eyelids have small hairs that cover the face except for around the eyes where they are worn away by tears and sweat. Browed eyelids have a bone called the zygomatic arch under the skin near the eye that keeps the eye socket open. This allows more space for the brain and helps sound travel out of the ear.
Blinking is controlled by a nerve called the oculomotor nerve. It sends signals to different parts of the brain when there is need for more blood flow to the eye to help it process more information. If the signal reaches the part of the brain that controls facial muscles, the eyelid will close automatically. If however, the signal goes to another part of the brain, then this tells the body not to blink.
Blinking reflexes are controlled by a number of muscles. The orbicularis oculi and the levator palpebrae superioris muscles govern the opening and shutting of the upper eyelid. The orbicularis oculi muscle shuts the eye, whereas the levator palpebrae muscle contracts to open it. The third major group of muscles involved in the blinking mechanism is made up of the facial muscles. The mentalis muscle pulls the eyeball forward to blink, and the frontalis muscle raises the brow to blink. There are also small muscles behind the eyeball that are responsible for moving it back and forth during a blink. These muscles are not used to open or close the eye but rather to adjust its position.
The orbicularis oculi is a flat muscle that covers most of the outer surface of the eye. It functions to open and close the eye. When you sleep at night, this muscle is very active because it is trying to keep the eye closed. As you wake in the morning, this muscle starts to relax if you are not making any sudden movements with your head, because it does not want anything to hurt your eye. If you continue to move your head around slowly, the orbicularis oculi will eventually get tired and not be able to shut your eye anymore.