VISUAL PATHWAY , ORBIT, EXTRAOCULAR MUSCLES OF THE EYE

 VISUAL PATHWAY

Each eyeball acts as a camera; it perceives the images   
and relays the sensations to the brain (occipital
cortex) via visual pathway which comprises optic
nerves, optic chiasma, optic tracts, geniculate bodies
and optic radiations

 
ORBIT, EXTRAOCULAR MUSCLES AND APPENDAGES OF THE EYE

Each eyeball is suspended by extraocular muscles and fascial sheaths in a quadrilateral pyramid-shaped bony cavity called orbit (Fig. 1.4). Each eyeball is
located in the anterior orbit, nearer to the roof and lateral wall than to the floor and medial wall. Each eye is protected anteriorly by two shutters called the eyelids. The anterior part of the sclera and posterior surface of lids are lined by a thin membrane called conjunctiva. For smooth functioning, the cornea and conjunctiva are to be kept moist by tears which are produced by lacrimal gland and drained by the lacrimal passages. These structures (eyelids, eyebrows,conjunctiva and lacrimal apparatus) are collectively called ‘the appendages of the eye’.

 Visceral mesoderm of maxillary process.

Before going into the development of individual structures, it will be helpful to understand the formation of optic vesicle, lens placode, optic cup and changes in the surrounding mesenchyme, which play a major role in the development of the eye and its related structures.