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121
in the pupillary light reflex, 4 neuronal pathways are involved, name them.
explain the mechansims of the pupillary light reflex.
explain the mechansims of the pupillary light reflex.
Light Reflex - 4 Neurones
First - connects retinal with pre-tectal nucleus in midbrain
Second - pretectal nucleus to Edinger-Westphal nuclues
Third - E-W to ciliary ganglion
Fourth Ciliary ganglion to innervate sphincter pupillae
The pretectal area of the midbrain receives bilateral input from collaterals of ganglion cell axons, signalling the detection of light by either retina. There is then a bilateral projection to the Edinger-Westphal nuclei that provide preganglionic parasympathetic input to the ciliary ganglia. Form these, postganglionic parasympathetic fibres innervate the pupillary constrictor muscle. both eyes constrict
First - connects retinal with pre-tectal nucleus in midbrain
Second - pretectal nucleus to Edinger-Westphal nuclues
Third - E-W to ciliary ganglion
Fourth Ciliary ganglion to innervate sphincter pupillae
The pretectal area of the midbrain receives bilateral input from collaterals of ganglion cell axons, signalling the detection of light by either retina. There is then a bilateral projection to the Edinger-Westphal nuclei that provide preganglionic parasympathetic input to the ciliary ganglia. Form these, postganglionic parasympathetic fibres innervate the pupillary constrictor muscle. both eyes constrict
