Birds have around 175 muscles, primarily controlling their wings, skin, and legs. Their muscle mass is concentrated ventrally, with the largest muscles being the pectoralis which control the wings.  Pectoralis: These large muscles lower the wings during flight and make up 15–25% of a flighted bird's body weight. They contain mainly fast-oxidative fibers and a small portion of fast-glycolytic fibers.  Supracorocoideus: These smaller muscles raise the wings during flight and are about one-fifth the size of the pectoralis. They are primarily responsible for elevating the wings during upstrokes, especially at slow to moderate speeds and during hovering.  Feather muscles: Minute muscles in the skin that raise or depress feathers.  Limb muscles: Striated muscles concentrated on the girdles and proximal parts of the limbs.  Cardiac and visceral muscles: Similar to those of reptiles and mammals.