Pupillary and Eyelid Abnormalities PDF

17 Pupillary and Eyelid Abnormalities...

17 Pupillary and Eyelid Abnormalities Matthew J. Thurtell, Janet C. Rucker OUTLINE Pupillary Abnormalities, 191 Eyelid Abnormalities, 198 Pupil Anatomy and Neural Control, 191 Eyelid Anatomy and Neural Control, 198 Normal Pupil Phenomena, 191 Pathological Conditions of the Eyelids, 198 Afferent Pathological Conditions of the Pupils, 192 Efferent Pathological Conditions of the Pupils, 192 PUPILLARY ABNORMALITIES second-order neurons exit to the paravertebral sympathetic chain via the ventral horns. They pass by the lung apex and then ascend with the Pupil Anatomy and Neural Control common and internal carotid arteries to reach the superior cervical The size of the pupil is determined by the balance of action between two ganglion in the neck, at the angle of the jaw, where they synapse with muscles embedded in the iris: the sphincter pupillae, under parasym- the third-order neurons. At this point, sudomotor fibers related to pathetic control, and the dilator pupillae, under sympathetic control. facial sweating separate anatomically from those fibers serving pupil- The sphincter is located circumferentially around the pupil and con- lary dilation. From the superior cervical ganglion, third-order neurons stricts the pupil. The dilator is situated radially and dilates the pupil. continue their ascent with the internal carotid artery through the skull On exposure to light, the pupil constricts as a result of the pupillary base and into the cavernous sinus, where they temporarily join the light reflex (Fig. 17.1). The afferent limb of the light reflex originates abducens nerve. They then join branches of the trigeminal nerve, with in the retinal ganglion cells and travels via the optic nerve, chiasm, which they enter the orbit and reach the dilator muscle via the long and optic tract to the dorsal midbrain pretectum, just rostral to the ciliary nerves (see Fig. 17.2). superior colliculus, from which neuronal signals are relayed bilaterally to the paired parasympathetic Edinger-Westphal nuclei (Nester et al., Normal Pupil Phenomena 2010; Papageorgiou et al., 2009). In primate studies, the pretectal oli- Hippus, or pupillary unrest, is a nonrhythmical, small-amplitude (