Pupillary Control Flashcards
What is miosis?
Miosis is constriction of the pupil.
What causes miosis?
Parasympathetic innvervation
What is the first order neuron involved in miosis?
Neurons from the Edinger-Westphal nucleus to the ciliary ganglion via cranial nerve 3.
What is the second order neuron involved in miosis?
Neurons from the short ciliary nerves travel to the pupillary sphincter muscles.
What is the pupillary light reflex?
Light in either retina sends a signal via afferent fibers via cranial nerve 2 to pretectal nuclei in the midbrain that activates bilateral Edinger-Westphal nuclei. The end result is bilateral pupillary constriction.
What is the result of the pupillary light reflex?
illumination in 1 eye results in bilateral pupillary constriction.
What is mydrisis?
Mydriasis is dilation of the pupils.
What causes mydriasis?
sympathetic innvervation
What is the first order neuron involved in mydriasis?
Nerves from the hypothalamus travel to the ciliospinal center of Budge (C8-T2)
What is the second order neuron involved in mydriasis?
From the ciliospinal center of Budge the nerves exit at T1 to the superior cervical ganglion. The superior cervical ganglion travels along the cervical sympathetic chain near the lung apex and subclavian vessels.
What is the third order neuron involved in mydriasis?
Third order neurons travel along the internal carotid artery through the cavernous sinus and enter the orbit as the long ciliary nerve to the pupillary dilator muscles.
What else to sympathetic fibers innervate in the eye?
Sympathetic fibers also innervate smooth muscle of the eyelids (minor retractors) and the sweat glands of the forehead and face.
