The chest muscles (pecs) are often thought of as a single muscle, but they actually have three distinct parts, each starting from a different area. 💥 The clavicular region (upper pecs) begins at the inner half of your collarbone. 💥 The sternal region (mid pecs) starts from the front of your breastbone (sternum). 💥 The costal region (lower pecs) comes from the upper part of your ribcage. These three parts work together to move your arms, but each one has its own unique role based on its positi