Do opera singers use muscles in their back to support the voice?
There are many muscles in the back that are used for the purpose of helping support the voice and holding power of the outward position of the diaphragm and rib cage. When one breathes properly the ribs expand out including all around the back area then we hold that to support the breathe so we can HOLD BACK THE BREATH, BREATH CONTROL (this is where the difficulty comes in) learning how to strengthen the back muscles along with the diaphragm muscles. If you can sing with a lighted candle four inches away from you without blowing it out you are doing great and on your way to terrific breath control.