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 World Colored Light Heavyweight Championship The World Colored Light Heavyweight Championship was a title created in 1921, when African American boxers were prevented from contending for the world light heavyweight title by the color bar. On 30 May 1921, Kid Norfolk fought Lee Anderson for the new colored light heavyweight title in a scheduled 10-round bout in Phoenix, Arizona. Anderson won on a T.K.O. when Norfolk returned to his corner in the ninth round, being unable to continue to fight. (They would meet another three times in non-title bouts between 1922 and 1924, and The Kid prevailed each time.) Anderson