(a) The space between the cornea and the lens is called the aqueous chamber and contains a thin watery fluid called aqueous humor. The space between the lens and the retina is called the vitreous chamber and is filled with a transparent gel called vitreous humor.
(b) The optic nerves leave the eye and the retinal blood vessels enter it at a point medial to and slightly above the posterior pole of the eyeball called the spot. It doesn’t contain any photoreceptor cells (rods and cones). At the posterior pole of the eye lateral to the spot, is a yellowish pigmented spot called macula lutea (yellow spot). It contains cones only and the point where the visual acuity is the greatest.
(d) Cranial nerves are the nerves that emerge directly from the brain stem in contrast to spinal nerves which emerge from segments of the spinal cord.
