primarymuscle
nounUK /ˈpraɪ.mə.ri ˈmʌs.əl/
US /ˈpraɪ.mɛr.i ˈmʌs.əl/
The main muscle that does most of the work when you move.
Your biceps is the primary muscle you use to lift a heavy bag.
OTHER MEANINGS
2. The muscle that starts a movement in a group of muscles.
The primary muscle fires first, then the helpers join in.
3. The most important muscle for a certain sport or action.
For a swimmer, the shoulder is a primary muscle group.
4. The muscle a doctor checks first during an exam.
The doctor tested the primary muscle in his arm.