![]() Of note, the pupillary changes themselves are generally independent of a light source. In general, hippus is most noticable when a patient is having his or her pupils examined with a light. The name itself comes from the Greek word hippos which means horse, presumably because the movement of the pupil was thought to look like a galloping horse. The condition is also characterized by the fact that this contraction and dilation of the pupil is rhythmic in nature but is also irregular. The condition called hippus is also called pupillary athetosis, or spasmodic, rhythmic dilation and constriction of the pupils. He or she can perform a detailed history and physical exam, including the use of special equipment to examine all parts of the eye. Philadelphia: WB Saunders 2001.Questions about health and one's eyes are best answered by an ophthalmologist. Neuro-ophthalmology: Diagnosis and Management. (Reprinted with permission from Liu GT, Volpe NJ, Galetta SL. Sudomotor fibers, e.g., for sweating to the lower face, follow the external carotid and then the facial arteries. Fibers to the tarsal muscles (Muller’s muscles) also travel within the carotid plexus to the cavernous sinus then may join branches of the third nerve before reaching the upper and lower eyelids. ![]() The postganglionic axons ascend as a plexus intimately associated with the internal carotid artery to reach the cavernous sinus.The pupil fibers briefly join the sixth nerve then follow branches of the first division of the trigeminal nerve and the long ciliary nerve to reach the iris dilator muscle. These fibers synapse at the ciliospinal center of budge whose cell bodies lie in the intermediolateral gray column and whose axons exit the cord ipsilaterally at C8, T1, and T2 via the ventral roots.These second-order (preganglionic) fibers travel rostrally via the sympathetic chain, traverse the superior mediastinum, pass through the stellate ganglion and terminate in the superior cervical ganglion. First-order hypothalamic (central) neurons descend through the brain stem and cervical spinal cord. New York: Oxford University Press 2001.)įIGURE 11.2 Schematic diagram of the sympathetic innervation of the pupil and eyelids. Efferent pupillomotor impulses travel in the parasympathetic fibers of the oculomotor nerve, synapse in the ciliary ganglion of the orbit, and then pass via the short ciliary nerves to innervate the iris sphincter muscle. The neurons of the Edinger-Westphal subnucleus initiate the efferent limb of the pupillary light reflex, that is, pupilloconstriction. Each pretectal olivary nucleus distributes the afferent pupillary impulses to the ipsilateral and contralateral Edinger-Westphal subnucleus of the oculomotor nuclear complex. ![]() Pupillary information is conveyed from the eye to the brain by the melanopsin-expressing retinal ganglion cells and their axons project to the dorsal midbrain, synapsing in the pretectal olivary nucleus. The afferent limb originates in the retinal photoreceptors that convert light energy to a neural signal. FIGURE 11.1 Schematic diagram of the pupillary light reflex. ![]()
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