Human Eye Removable 47cm Model

8pcs/carton, 53x40x47cm, 10kgs

The model shows the eyeball with optic nerves and muscles in its natural position in the bony orbit. Dissectible into 10 parts, 3 times enlarged.

There are two eyes, situated on the left and the right of the face. They sit in two bony cavities called the orbits, which are present in the skull. Six extraocular muscles attach directly to the eyes to assist with movement. The front visible part of the eye is made up of the whitish sclera, a coloured iris, and the pupil. A thin layer called the conjunctiva sits on top of this. The front part is also called the anterior segment of the eye.

The eye is not shaped like a perfect sphere, rather it is a fused two-piece unit, composed of a anterior (front) segment and the posterior (back) segment. The anterior segment is made up of the cornea, iris and lens. The cornea is transparent and more curved, and is linked to the larger posterior segment, composed of the vitreous, retina, choroid and the outer white shell called the sclera. The cornea is typically about 11.5 mm (0.3 in) in diameter, and 0.5 mm (500 μm) in thickness near its center. The posterior chamber constitutes the remaining five-sixths; its diameter is typically about 24 mm. The cornea and sclera are connected by an area termed the limbus. The iris is the pigmented circular structure concentrically surrounding the center of the eye, the pupil, which appears to be black. The size of the pupil, which controls the amount of light entering the eye, is adjusted by the iris' dilator and sphincter muscles.

Light energy enters the eye through the cornea, through the pupil and then through the lens. The lens shape is changed for near focus (accommodation) and is controlled by the ciliary muscle. Photons of light falling on the light-sensitive cells of the retina (photoreceptor cones and rods) are converted into electrical signals that are transmitted to the brain by the optic nerve and interpreted as sight and vision.