Pectoral muscles

Pectoral muscles refers to either of the muscles that connect the front walls of the chest with the bones of the upper arm and shoulder:

In sports as well as bodybuilding, the pectoral muscles may colloquially be referred to as "pecs".

Pectoralis major muscle

The pectoralis major (/ˌpɛktəˈreɪlᵻs ˈmeɪdʒər/) (from Latin: pectus, breast) is a thick, fan-shaped muscle, situated at the chest (anterior) of the human body. It makes up the bulk of the chest muscles in the male and lies under the breast in the female. Underneath the pectoralis major is the pectoralis minor, a thin, triangular muscle. In sports as well as bodybuilding, the pectoral muscles may colloquially be referred to as "pecs".

Structure

It arises from the anterior surface of the sternal half of the clavicle; from breadth of the half of the anterior surface of the sternum, as low down as the attachment of the cartilage of the sixth or seventh rib; from the cartilages of all the true ribs, with the exception, frequently, of the first or seventh and from the aponeurosis of the abdominal external oblique muscle.

From this extensive origin the fibers converge toward their insertion; those arising from the clavicle pass obliquely downward and outwards (laterally), and are usually separated from the rest by a slight interval; those from the lower part of the sternum, and the cartilages of the lower true ribs, run upward and laterally, while the middle fibers pass horizontally.