what are pecs muscle

The pectoral muscles, colloquially referred to as "pecs," are the group of skeletal muscles that connect the upper extremities to the anterior and lateral thoracic walls. The pectoral region contains four muscles that exert a force on the upper limb: the pectoralis major, pectoralis minor, serratus anterior, and subclavius. The pectoralis major is the most superficial muscle in the pectoral region and is a thick, fan-shaped muscle that lies underneath the breast tissue and forms the anterior wall of the axilla. It is responsible for flexion, extension, and rotation of the humerus, the long bone of the upper arm, and is composed of a sternal head and a clavicular head. The pectoralis minor is a thin, triangular muscle located beneath the pectoralis major and attaches to the ribs, serving to stabilize the scapula, the large bone of the shoulder. The pectoral muscles are responsible for moving the upper extremities in a wide range of motion, including but not limited to flexion, adduction, and internal rotation of the humerus, stabilization of the scapula, as well as elevating and depressing the bones of the thorax.