Human Eye: Anatomy, parts and structure The eye is the photo-receptor organ. Size and shape: Human eye is spherical about 2.5 cm in diameter. Location: it is situated on an orbit of skull and is supplied by optic nerve. There are 6 sets of muscles attached to outer surface of eye ball which helps to rotate it in different direction. Four sets of these muscles are straight muscles; superior, inferior, medial and lateral rectal muscle and two sets are oblique muscles; superior and inferior oblique muscles. Structurally two eyes are separated but some of their activities are coordinated so that they functions as a pair. Anatomical structure of Eye Eye ball consists of three layers Outer fibrous layer: Sclera, cornea and conjunctiva Middle vascular layer: ciliary body, choroid and iris Inner layer: retina I. Outer fibrous layer: It consists of following parts. 1. Sclera: It is outermost supporting layer consists of thick membrane of tough fibrous c...