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
The Widening Gyre (album) Poison Glen". On 5 February 2015, before its release, "The Widening Gyre" was awarded full marks by The Irish Post's columnist Joe Giltrap, describing the album as "a really nicely balanced album", "an album of pure quality", "a great album from a great band". The album received a very positive review from the New York-based Irish Voice's music critic Paul Keating, writing: "[Would] Altan have shared stages and off-hours sparks with a wealth of kindred musical spirits from both sides of the Atlantic and the Irish Sea [over the past thirty years], the recording shows that depth and creativity with