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7 Cards in this Set
- Front
- Back
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What are the 3 components of the accommodation reflex? |
Pupil Constriction Lens accommodation Convergence of the eyes |
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What happens during pupil constriction and why? |
The pupil is constricted by the constrictor pupillae muscle. This blocks the light scattered by the peripheral cornea which would cause a blurred image. |
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Which muscle produces lens accommodation and how is it controlled? |
The ciliary muscle produces accommodation of the lens through contraction. It is controlled by parasympathetic fibres arising from the ciliary ganglion (part of the trigeminal nerve) |
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What does accommodation do? |
Contraction of the ciliary muscles makes the lens more concave and shorten its focal length. This allows focussing on nearby objects. |
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What is convergence and how is it achieved? |
Convergence is the ability of both eyes to simultaneously move inwards towards each other. It is caused by contraction of both medial rectus muscles. |
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What is the pupillary light reflex? |
A reflex that controls the diameter of the pupil in response to light. |
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Why does light shone in one eye effect the diameter of both pupils? |
The signal from one eye is relayed to the right and left pretectal nuclei (due to the splitting of the visual pathway) This stimulates both sides of the Eddinger-Westphal nuclei which generate action potentials in both occulomotor nerves. This causes both pupils to constrict. |
