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Which muscles raise and lower a bird’s wings?

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A zebra finch (Taeniopygia guttata) with a bright orange beak, gray head, orange cheek patch, and black-and-white striped tail perches on a branch. — Bird A brightly colored zebra finch (*Taeniopygia guttata*) perched on a branch.

The up-and-down strokes of a bird’s wing are powered by large chest muscles that originate from the sternum (breastbone) and attach to the humerus (upper arm bone).1

Lowering the wing: This movement is produced by the contraction of the large pectoral muscles, which extend from the sternum to the lower surface of the humerus.1
Raising the wing: This movement is produced by the contraction of a smaller anterior pectoral muscle. This muscle is attached to the upper surface of the humerus by a long tendon.1

Together, these muscles allow birds to alter the lateral extent and regional inclination of their wings to achieve flight.1