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
World Colored Light Heavyweight Championship defended the title on the Fourth of July 1921 in a 10-round bout in Phoenix, Arizona, beating Rough House Ware on points. When Norfolk fought The Jamaica Kid on 20 December 1921 at Madison Square Garden in New York City, he had claimed the world colored light heavyweight title. He beat the Jamaica Kid on points in an eight-round bout. In Atlanta on 30 January 1922, Norfolk faced Tiger Flowers, the boxer who would become the first African American world middleweight champ in 1926, K.O.-ing him in third round of a 10-rounder. He apparently had vacated the title when he