Eye

The eyes are situated within the bony orbital sockets in the upper face.

These are covered over by the upper and lower eyelids that surround a palpebral fissure. At the margins of the eyelids we can find eyelashes. Their hair follicles, if get infected, can lead to a painful inflammatory swelling called the ‘stye’.

The bony orbital cavity is lined on the inside by periosteum (called periorbita). The space between the periorbita and fascial sheath of the eye ball is filled in with periorbital fat pads, that provide support to the eye ball.

A muscle found within the eyelids, called the orbicularis oculi, helps close the eyelids. While another muscle called the levator palpebrae superioris, helps lifting up the upper eyelid. Within the orbit, a group of six extra-ocular muscles are responsible for the conjugate movements of the eye balls.

The eye ball, in itself, has a tough outer covering called the sclera, which is transparent in the front–called the cornea–to allow for light to enter the eye. Inner to the sclera lies the choroid, which is underlined by the retina in the back of the eye. The eye ball is divided into an anterior aqueous humor and posterior vitreous humor compartments. The anterior compartment is further subdivided into anterior and posterior chambers, with the help of ciliary muscle. The latter surrounds a central aperture called the pupil which is plugged in by the lens. The light has to travel and refract through the cornea and the lens, to eventually reach up to the retina for image perception. From here onwards, visual information from the retina is transmitted to the occipital cortex of the brain, via the optic nerve pathway.