Sheep's Eye Dissection

In this lab, we got to dissect a sheep's eye in order to examine its anatomy and physiology. One major difference I noticed as our group started opening up the eye was that the iris was oval-shaped and the pupil was lying on its side horizontally, while human eyes have round iris's and round pupils.

On the outside of the eye, extrinsic muscle bundles are found side by side with yellowish fat which helps protect the eye. The cornea is the cloudy, black-looking centerpiece of the eye, though it's clear and cloudy (not black) outside of the picture. Inside the eye, the eye's anatomy is arranged so that the cornea is the first thing that light hits as it enters the eye. Next, it is the pupil which is in the middle of the iris, then the lens is behind the pupil while the sclera surrounds the rest of the eye. The vitreous humor fills the inside of the eye so that everything is held in place. The retina is the yellow film-like layer (shown in the third picture below) that's located at the back of the eye. Behind this object, in order, there's the tapetum lucid, the choroid coat, and the optic nerve.

The physiology of the eye eye allows us to have our sense of vision, and our perception of light and dark. The cornea helps protect the eye from things such as dirt which is why it is located at the front of the eye instead of inside it or at the back of it. Behind the cornea, the pupil is the one opening in the eye which allows light to enter this item, and the lens behind the pupil helps bend the light to focus on objects that we can see. The Ciliary body holds the lens in place and the suspensory ligaments adjust it's size and therefore, focus. In between the lens and the retina is the vitreous humor which provides nutrients for the inside of the eye and maintains the eye's pressure. The images from the lens are then projected onto the retina, which converts them into signals that it sends to the brain via the optic nerve. The dark choroid coat behind the retina helps with this process by absorbing light so that it will not scatter around the eye.



(outside look at the sheep's eye)


Inside of the eye left, and the back of the
inside of the eye right showing the retina
on top, then the tapetum lucid, the choroid
coat, and behind that, the optic nerve.


(image of the lens, small white circle, and
the choroid coat (black) inside the eye)


(assembly of all the dissected parts of the eye,
excluding the fat)