Iris sphincter muscle Iris sphincter muscle The iris sphincter muscle (pupillary sphincter, pupillary constrictor, circular muscle of iris, circular fibers) is a muscle in the part of the eye called the iris. It encircles the pupil of the iris, appropriate to its function as a constrictor of the pupil. It is found in vertebrates and some cephalopods. Initially, all the myocytes are of the smooth muscle type but, later in life, most cells are of the striated muscle type. Its dimensions are about 0.75 mm wide by 0.15 mm thick. In humans, it functions to constrict the pupil in bright light (pupillary light
There Is a Light That Never Goes Out There Is a Light That Never Goes Out "There Is a Light That Never Goes Out" is a song by the English rock band the Smiths, written by guitarist Johnny Marr and singer Morrissey. Featured on the band's third studio album "The Queen Is Dead", it was not released as a single in the United Kingdom until 1992, five years after their split. It peaked at No. 25 on the UK Singles Chart. The song has received considerable critical acclaim; in 2014, "NME" listed "There Is a Light That Never Goes Out" as the 12th greatest song of all time.