What Is a Pectoralis Muscle?

In human anatomy, the term "pectoralis muscle" is broadly used to describe any muscle that attaches the front chest wall to the shoulder. There are a couple of different muscles that fit this description, but the group is made primarily of muscles known formally as pectoralis major and pectoralis minor. These muscles give definition to the chest and are often the targeted recipients of many upper-body exercises and weight lifting routines. The major muscle group is often referred to colloquially as the “pecs.” Strong muscles in this region can often assist with tasks like lifting and endurance, and there are a number of exercises people can perform to improve muscular tone and function. There are some differences in the muscle based on gender, though, with the fibers tending to be larger and thicker in males. Women who perform targeted exercises can often develop their muscles to be more noticeable, but as they sit directly under the breast tissue in most cases, it’s usually harder for females to achieve the bulging pecs of their male counterparts. Caution is usually advised for all weightlifters regardless of gender, since injuries to these muscles can be serious and often take quite a while to heal.

The pectoralis muscles control posture, which affects many other health issues, including respiration and circulation. These muscles can become tight when one is leaning over a computer or desk, because the muscles are in a constant state of flexion. When tight, these muscle pull the shoulders into a hunched position, with the head protruding forward. The pectoralis major muscle also pulls the shoulders forward into a hunched position as a result of excessive workouts that don’t also work the corresponding back and neck muscles.

The pectoralis major muscle is one of the body’s largest, and is attached at the clavicle, sternum and upper ribs. It ends in a tendon that inserts into the bicipital groove of the humerus, the upper arm bone; its main job is to move the shoulder joint, enabling the arms to move forward, though it also plays a role in breathing deeply.

The pectoralis minor muscle, by contrast, is much smaller and normally sits just beneath the pectoralis major. It attaches to the third, fourth and fifth ribs and ends in a tendon that inserts into the coracoid process of the shoulder blade. This smaller muscle moves the shoulder forward and downward, allowing a downward pushing motion.

The pectoralis major muscles are commonly targeted by weightlifters and exercise afficinados, and in most cases developing them to be big and bulging is relatively easily accomplished for men who are willing to stick to a plan and a regimen, at least when compared to creating pronouncement in other, more difficult to access muscular groups. It’s often the case that the pecs are more important cosmetically to men as a sign of upper body strength. In females, the pecs are much less noticeable and mostly underneath the breast.

Breast implants for cosmetic or reconstructive purposes can be placed over or beneath the pectoralis major. There are doctors who prefer one way over the other. The most recommendations seem to prefer placing implants below the muscle, but there might be some loss of strength in a muscle that must be split to allow the implant.

Incline and decline bench presses, push-ups, flat dumbbell flyes and pullovers are all exercises to strengthen the pectoralis muscles. These muscles flex, laterally rotate, and help to adduct — or move toward the middle of the body — the upper arms. Most trainers recommend working the corresponding back muscles, the lattisimus dorsi, as hard as the pectoralis muscles in order to balance their effect and to avoid injuries.

Ruptures of the pectoralis major, while rare, can occur in weightlifting activities. Surgical repair is normally recommended in these cases, with nonsurgical treatment recommended only for older patients or for tears of the muscle's belly. The pectoralis minor, when tight, can also impinge on the brachial nerve, causing numbness and tingling in the hand. Most of the time, relaxing the muscle will bring things back to normal.