![]() Constriction of both pupils occurs in response to bright light. The eye focuses the image in the center of the pupil. Light is reflected at the same spot in both eyes. The nurse recognizes that this reflex indicates that: a. For example, light shined in the left eye causes constriction of both the left pupil (direct response) and the right pupil (consensual response) and vice versa. A patient has a normal pupillary light reflex. Each pretectal nucleus projects bilaterally to both Edinger-Westphal nuclei so that both pupils constrict equally in response to light input from either side. ![]() ![]() Test each eye separately to see if he/she can read the 20/20 line on the chart. Name of the Cranial Nerve Cranial Nerve TEST 6 Have the subject stand 20 feet away from the eye chart. These parasympathetic pupillomotor fibers of CN 3 synapse in the ciliary ganglion in the orbit, and short ciliary neurons arising from the ciliary ganglion innervate the pupillary constrictor muscles of the iris. Watch for pupil constriction in the eye without the light. In the dorsal midbrain, the pretectal nuclei communicate with the Edinger-Westphal nuclei, which give rise to the efferent pupillary constrictor fibers that travel in the oculomotor nerves (CN 3). The afferent pupillary light reflex fibers travel through the optic nerves, optic chiasm, and optic tracts, and then separate from the optic tracts to proceed to the pretectal nuclei of the dorsal midbrain (note the separation of light reflex afferents from visual pathway fibers at this point the visual pathway fibers in the optic tracts proceed to the lateral geniculate nuclei see Fig. Pupillary constriction in response to light requires transmission of light information from the retina to the brain ( afferent pathway), and signals from the brain to constrict the pupils ( efferent pathway) ( Fig. ![]()
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