Pupillary light reflex The pupillary reflex mediates pupil contraction in response to light. Afferent signals from CN II fibres are passed to the pretectal area of the brainstem and lead to stimulation of the Edinger-westphal nucleus. Consequently, parasympathetic CN III efferent fibres mediate constriction of the pupil via sphincter pupillae. Since afferent signals split bilaterally at the optic chiasm, the reflex is consensual where shining light … Continue reading Ocular reflexes

The optic nerve consists of about 1.2 million very fine retinal ganglion cell fibres. The nerve within the orbit is slightly sinuous to allow for eye movements and is covered by extensions of the three layers of the meninges and a fine layer of cerebrospinal fluid. The two optic nerves form a flattened cross, the optic chiasm, which overlies the tuberculum and diaphragma sellae to … Continue reading Visual pathway