Mydriasis iris sphincter, composed of circularly arranged muscle fibers, and the iris dilator, composed of radially arranged muscle fibers. The sphincter is innervated by (signaled by nerves of) the parasympathetic nervous system, and the dilator by the sympathetic nervous system. Sympathetic stimulation of the adrenergic receptors causes the contraction of the radial muscle and subsequent dilation of the pupil. Conversely, parasympathetic stimulation causes contraction of the circular muscle and constriction of the pupil. The mechanism of mydriasis depends on the agent being used. It usually involves either a disruption of the parasympathetic nerve supply to the eye (which normally constricts the
What a piece of work is a man lines written by Montaigne: However, rather than being a direct influence on Shakespeare, Montaigne may have merely been reacting to the same general atmosphere of the time, making the source of these lines one of context rather than direct influence. What a piece of work is a man "What a piece of work is man!" is a phrase within a soliloquy by Prince Hamlet in William Shakespeare's play of the same name. Hamlet is reflecting, at first admiringly, and then despairingly, on the human condition. The soliloquy, spoken in the play by Prince Hamlet to Rosencrantz and Guildenstern in Act