10/30/2022 0 Comments Hippus pupilNear reflex: it occurs when we look at near object.Postganglionic fibers travel along the short ciliary nerves to innervate this sphincter pupillae. The pre ganglionic fibres enter the inferior division of the third nerve and via the nerve to the inferior oblique reach the ciliary ganglion to relay. Efferent pathway it consists of the parasympathetic fibres which arise from the Edinger-Westphal nucleus in the midbrain and travel along the oculomotor nerve.Internuncial fibres it connects each pretectal nucleus with Edinger-Westphal nuclei from both sides and This connection forms the base of consensual light reflex.And the fibers from the temporal retina will remain uncrossed and will Continue along the optic tract of the same site to terminate in the ipsilateral pretectal nucleus. Then it travel along the optic nerve to the optical chaisma where fivers from the nasal retina of each eye cross and travel along the opposite optic tract to terminate in the contralateral pretectal nucleus. Afferent fibres are extended in midbrain from retina up to the pretectal nucleus. Both reflexes are initiated by retinal photoreceptors that is rod cell and cone cell. The constriction of pupil in which the light is shone is called Direct light reflex and that of the other pupil is Consensual or indirect light reflex.
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