Eye muscles – 1

You may refer to last 4 articles Introduction to smooth muscle, Smooth muscle structure, Smooth muscle jobs and Smooth muscle contraction.

It is time now to consider the skeletal muscles. These are the bulky muscles. They are near the skin and their outlines can be easily seen and felt. They have tendons, those rope like end parts inserted into or originating from bones. All the photographs of bodybuilders we see in fitness magazines and sports sections of print media exhibit the skeletal muscles. However, not all skeletal muscles are massive some are quite small and delicate like the muscles of eye.

While you are looking at the computer screen to read this article, your eye muscles are moving, shifting, rotating your eyeballs so as to make the act of reading easy. I am referring to the muscles outside the eye known as the extraocular muscles.

There are seven such muscles - six attached to an eye ball and seventh to the upper eyelid.

We can move our upper eyelid but not the lower one. The lower eyelid does not have a special muscle just for itself. The movement of our upper eyelid is due to a muscle called levator palpebrae superioris. Blinking is a normal reflex movement of eye. Blinking ensures that a drop of tear coming from lacrimal gland spreads onto the cornea and keeps it transparent.

The other six extraocular muscles, in a coordinated fashion, move the eyeball in different directions.

Located in the eye socket human eye muscles can not be easily inspected, any one muscle's movement changes the tension and length of the other muscles of eye, and they work together and not in isolation. The head and neck also moves and affects the movement of the eye muscles. All these factors make it difficult to say what exactly is the action of each one of these muscles but following generalizations may be made - The six muscles that move the eyeball are the four recti and two obliques -

1. Lateral rectus - moves the eye outward, away from the nose
2. Medial rectus - moves the eye toward the nose
   
   
3. Superior rectus - moves the eye upward
4. Inferior rectus - moves the eye downward
   
   
5. Superior oblique -has several actions on the eye , but primarily causes the eye to twist outward
   The copyright of the article Eye muscles – 1 in Human Anatomy is owned by Narayan Dattatray Wadadekar. Permission to republish Eye muscles – 1 in print or online must be granted by the author in writing.

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