PECtorals

The pectoralis major is the most superficial muscle in the pectoral region. It serves as the anterior wall of the axilla (armpit), and forms a large part of the contour of the chest

serratus anterior

The serratus anterior aids in the upward rotation of the scapula, working alongside the trapezius muscle.

intercostals

The intercostal muscles are part of your ribcage, linking each rib to its neighbors. These muscles work in sets. Their flexing action makes your ribcage expand or shrink depending on which set takes the lead. That makes them a key force in every breath you take.

thoracic spine

The thoracic spine is the middle section of your spine. It starts at the base of your neck and ends at the bottom of your ribs. It’s the longest section of your spine. Your thoracic spine consists of 12 vertebrae, labeled T1 through T12.