Names of the spiral arms in the milky way

The Milky Way has four main spiral arms: the Norma and Cygnus arm, Sagittarius , Scutum-Crux , and Perseus. The Sun is located in a minor arm, or spur, named the Orion Spur. The galactic disk itself is about 100,000 light years across, and the bar at the center is estimated to be about 27,000 light years long