Avian flight muscle is like an engine with a large stroke—developing tension over a much longer relative muscle length than human muscle. This allows a large amplitude wing-flapping motion.
Four muscles—two on each side of the chest (the “depressors”)—are the major engines that power the downstroke of a bird’s wings. They form the breast of the bird and you have probably carved and eaten them from a chicken or turkey. Two smaller muscles (the “elevators”) raise the wings, working through a groove over the shoulder. This smaller size reflects the fact that wing-raise can be assisted by drag on the outstretched surface. Opposing muscles are not usually on the same side of a joint but this arrangement keeps the bird’s center of gravity below the wings like a high-wing airplane. This increases flight stability. Different birds have various combinations of slow and fast flight muscles depending on their lifestyles.
LEARN MORE ABOUT THE ENGINES OF FLIGHT
In the Museum exhibit, wee asked: When you eat turkey breast, what part of the bird are you eating?
The answer is: The flight muscles of the Turkey
The flight muscles of the Turkey that are called the pectoralis major and minor (the wing depressors) and supracoracoideus (the wing elevator).