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 Pushkin, what a son of a bitch! What a Pushkin, what a son of a bitch! "What a Pushkin, what a son of a bitch!" (; sometimes separated by exclamation mark instead of comma) is a catchphrase and winged word from Alexander Pushkin's correspondence with one of his friends, poet Pyotr Vyazemsky. The phrase commonly expresses a joy after finishing one's work and appears particularly in several Russian literary works. In a letter dated circa November 7 or beginning of October, 1825 Pushkin, celebrating his finished drama "Boris Godunov" wrote to Vyazemsky: That was preceded by what Pushkin wrote to Vyazemsky on July 13 of the same