<prompt> Injury to which of the following structures causes constricted pupils even when room lighting is dim?Trochlear nerveSuperior cervical ganglionOculomotor nerveOphthalmic nerve  <response>: Postganglionic sympathetic fibers that originate from the superior cervical ganglion and innervate the dilator pupillae radial muscles of the iris are damaged. So the pupil remains small in a dimly lit room. Other nerves mentioned contain no sympathetic fibers, but the oculomotor nerve contains preganglionic parasympathetic fibers. 