A pair of muscles that lowers the wings of birds in flight(noun)
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Use "pectoralis" in a sentence
"In Germany, Halsted had seen Volkmann remove not just the breast, but a thin, fanlike muscle spread out immediately under the breast called the pectoralis minor, in the hopes of cleaning out the minor fragments of leftover cancer."
"A great, fan-shaped muscle, called the pectoralis major, lies on the chest."
"It can recur on the chest wall, which is called the pectoralis muscle."