Anatomy and Physiology of a Sheep Eye

 Today in class, we completed a sheep eyeball dissection, in which we used a pair of scissors, probes, tweezers, and a blade to cut through a sheep eyeball and identify the structures. It was interesting to see how each part of the eyeball play such an important role in the anatomy and physiology of the sheep; for instance, fat tissue surrounding the eye socket helps keep the eye in place when moving while the pupil regulates the amount of light entering the eye.

 Surface of Eye (Front Side)

The sclera is a white layer that forms a wall around the eyeball and helps to protect the eye from injury. We noticed that the sclera was pretty difficult to cut due to its important function.

The eyelid is responsible for shielding away dust, dirt, and other foreign particles from the eye.

The cornea is also responsible for shielding foreign particles from the eye; it acts as the eye's outermost lens and controls the entry of light in the eye. While living organisms have a clear cornea, nonliving organisms possess a cloudy cornea.



Backside of Eyeball

The fatty tissue is responsible for helping to cushion the eye when moving while the optic nerve, which is made of nerve cells uses visual information to send information from the retina to the brain.

Controls the horizontal, vertical, and rotating movements of the eye.

                                               

Inside the Eye

The retina receives light that the lens has focused and is connected to the choroid at the optic disc or the blind spot. 

The lens is responsible for changing the focal distance of the eye in order for the object to focus. This enables for an object to be formed on the retina. The suspensory ligament, which is located around the lens, is responsible for adjusting the shape of the lens to make it either more or less curved. 

The iris is the colored portion of the eye; inside, there is a pupil, which controls the amount of light that enters the eye.  The ciliary body, located beneath the iris, has many important functions, including the regulation of aqueous humor (helps maintain the shape of the eye) and the ability to have the muscle change the shape of the lens when the eyes focus on an object.

The vitreous humor has a semi-fluid consistency that fills the center cavity of the eye and is also responsible for helping to maintain the shape of the eye.  Like the cornea, the vitreous humor is sightly cloudy in a nonliving animal.