The eye | Acland's Video Atlas of Human Anatomy Skip to main content
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Now we'll move on, to look at the main externally visible parts of the eye itself. In life we see only a small part of the eye: even at the limit of eye movement we see less than half of its circumference.

Here's the eye seen from above. It occupies only the anterior part of the orbit. The space behind it is largely occupied by fat, that's been removed in this dissection.

The tough outer coat of the eye is the sclera. The sclera extends from here behind, where the optic nerve passes though it, all the way round to here in front, where it becomes continuous with the transparent cornea.

The cornea is the transparent window that allows light to enter the eye. The cornea is more sharply curved than the sclera: it bulges forwards. Behind the cornea, the colored iris forms an incomplete partition within the eye.

At the center of the iris is a clear opening, the pupil. The size of the pupil is constantly changing, to limit the amount of light that enters the eye. The iris is formed chiefly of muscle fibers. Fibers arranged radially cause the pupil to dilate, fibers arranged circumferentially both here, and out here, make it constrict.

The lens of the eye is just behind the iris and the pupil. Here light from a slit lamp is coming in from the left side. Down here where it's very bright the light is hitting the iris. Here it's hitting the anterior surface of the lens.

The internal structures of the eye are so delicate and so readily displaced that they can't be well shown by dissection. They're better understood by referring to microscopic images and diagrams, to which I hope you'll have access.

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