noun, noun which may take the genitive case particle 'no'
pectoral muscle; pecs
Anatomical term for the chest muscle; used in medical, fitness, and everyday contexts.
胸筋を鍛えるトレーニングを始めた。
I started training to build my pectoral muscles.
胸筋の痛みが続いている。
I have persistent pain in my pectoral muscle.