The blind spot of the human eye is the region where:
- A.Cones are most densely packed
- B.The optic nerve leaves the eyeball and no photoreceptors are present
- C.The aqueous humour is produced
- D.The ciliary muscles are attached to the lens
Correct answer
Explanation
The correct answer is B, the optic nerve leaves the eyeball and no photoreceptors are present. The blind spot, also called the optic disc, is the small area of the retina from which the fibres of the optic nerve pass out of the eyeball; it has neither rods nor cones, so an image falling on it is not registered and we do not notice the gap only because the brain fills it in from the other eye. Option A is wrong because the densest packing of cones is at the yellow spot, or macula, which is the point of sharpest vision and is therefore the opposite of the blind spot. Option C is wrong because the aqueous humour is secreted by the ciliary body into the chamber between the cornea and the lens. Option D is wrong because the ciliary muscles are attached to the lens through suspensory ligaments and bring about accommodation.
Read the full article: Sense Organs: Eye, Ear, Nose, Tongue and Skin
Practice Questions
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