The Eye
Eye FloatersThe Anatomy of the Eye
Superior Rectus Muscle
The superior rectus muscle is a muscle in the orbit that elevates, adducts, and rotates the eye medially.
SceleraThe sclera is the white outer coating of the eye. It is made of tough fibrin connective tissue. It gives the eye its shape and helps to protect the delicate inner parts.
IrisThe iris is the colored part of the eye. It opens up in dark rooms and at night to let more light into the eye. Conversely, in bright lights the iris constricts to decrease the amount of light that enters the back of the eye.
LensThe lens is responsible for helping to fine adjust the focus of the eye. The lens changes shape to allow clear vision both in the distance and for reading.
CorneaThe cornea is the curved, transparent layer that covers the front part of the eye and protects its inner structures. Together with the lens, the cornea refracts light and consequently helps the eye to focus. The cornea gives a larger contribution to the total refraction than the lens, but whereas the curvature of the lens can be adjusted to "tune" the focus, the curvature of the cornea is fixed.
The cornea has sensitive nerve endings; touch of the cornea causes an involuntary reflex to close the eyelid. Because transparency is of prime importance, the cornea does not have blood vessels; it receives nutrients via diffusion from the tear fluid at the outside and the aqueous humour at the inside. In humans, the cornea has a diameter of about 12 mm and a thickness of 0.5 - 0.7 mm in the centre and 1.0 - 1.2 mm at the periphery.
Anterior ChamberBetween the cornea and the iris is a space called the anterior chamber. This space is filled with a clear water-like solution.
ConjunctivaThe conjunctiva is a membrane that covers the sclera (white part of the eye) and lines the inside of the eyelids. It helps lubricate the eye by producing mucus and tears, although not as much tears as the lacrimal gland.
Inferior Rectus MuscleThe inferior rectus muscle is a muscle in the orbit that depresses, adducts, and rotates the eye laterally. As with most of the muscles of the orbit, it is innervated by the oculomotor nerve (Cranial Nerve III).
Optic NerveThe optic nerve is the nerve that transmits visual information from the retina to the brain.
Fovea CentralisThe word fovea refers to any small pit or depression in the surface of a structure or organ. The Fovea Centralis is a small depression in the centre of the macula lutea of the retina. The average diameter is 0.3 mm and the area is rod-free area with very thin, densely packed cones, allowing for a point of maximal focus.
RetinaThe retina is a thin film of tissue (like film in a camera) where images are brought into focus. The retina lines the inside surface of the eyeball. The retina is connected to the brain where the visual signals are processed.
VitreousThe vitreous is a clear jelly-like material which fills the inside of the eyeball. Light passes through the vitreous on it's way to being focused onto the retina.
PupilThe pupil is the black spot in the centre of the iris. Actually, the pupil is the name given to the opening in the iris through which light passes.