The pectorals muscles are located on the chest. The group consists of two muscles, the pectoralis major and the pectoralis minor.
Pectorals muscle and actions
When people talk about their pectoral muscles (also called pecs), which define the shape and appearance of the chest. It controls many of the arm movements, including flexing and rotating the arm and pushing it in towards the midline (adduction) of the body.
The pectoralis major is a thick, fan-shaped muscle that attaches to the upper arm, extends from the chest to the collarbone, and attaches to the sternum, the bone in the middle of the chest. Breast tissue sits on top of it.  
Pectoralis major has two heads:
- Clavicular Head
- Sternocostal Head
Composed of two ends, the pectoralis major abducts horizontally and internally rotates the humerus, which is the largest bone in the arm.
1. Clavicular Head
The clavicular head is located in the upper part of the chest near the shoulders. Originates from the anterior surface of the medial half of the clavicle.
2. Sternocostal Head
The sternocostal head is located in the lower part of the pectoralis major. In addition to the above movements, the clavicular head assists in horizontal abduction when the arm is held at 110 degrees. The sternal head assists with the downward extension of an outstretched arm.
This head is the larger of the two ends and originates from the anterior surface of the manubrium and the body of the sternum, the anterior surface of the superior six costal cartilages. Superior part of the aponeurosis of the external oblique muscle. 
The pectoralis minor is located under the pectoralis major and draw the scapula down and forward. Pectoralis minor is triangular and both form the anterior wall of the axilla.
Pectoralis minor originates from the margin of the third to fifth ribs adjacent to the costochondral junction. The fibers consequently pass upward and laterally and insert into the medial border and superior surface of the coracoid process of the scapula.
It is important in stabilization of the scapula by pulling it downward and anteriorly against the thoracic wall. 
The pectoralis minor muscle forms a passage between the ribs for the passage of both the brachial plexus and the subclavian artery and vein. If the muscle is shortened/tightened, this abnormal tension: negatively affects the scapulohumeral rhythm; Can also cause thoracic outlet syndrome. 
The primary actions of this muscle include stabilization, depression, abduction, or dilation of the scapula, internal rotation and downward rotation.
When the ribs are fixed, this muscle brings the scapula forward, Both pectoralis muscles work with the serratus anterior muscles to create full range of motion for the scapula.
Pectoralis Minor Role
- The pectoral waistband elevates the ribs for deep inspiration when stationary or elevated.
- In a state of good alignment, with the scapula immobilized, the pectoralis minor acts as an auxiliary muscle of the spur.
It is important to maintain shoulder stability when performing chest exercises, as rotator cuff injuries can occur with improper form.
Exercises performed on an incline are effective in developing the upper, clavicular part of the pectoralis.
While pressing exercises such as the bench press and dumbbell press should be staples in any strength training routine, they rely heavily on the triceps and shoulders as auxiliary movers. Exercises that focus exclusively on horizontal abduction, such as the dumbbell fly, can be effective because they isolate the muscles and rely least on assisted movers.
Controlled motion Each pectoral exercise has a different technique, which means you need to adjust position and technique, but the principle of using control is essential. That way you’ll be sure you’re using the right technique for the exercise and, importantly, make sure you’re targeting the right muscles.
Target the muscle
Target the muscle, it goes hand in hand with the first point. A bench press should work the chest, not the shoulders or arms. So if you feel more movement in the front parts than in the chest, adjust the position or weight until the technique is doing what it’s meant for.
Use a weight that can be handled, it is very important to build on the first two points, choose the right weight and build from there. Don’t let the ego get to you, train smart before you can work hard. It’s true that the pec muscles respond better to heavy loads, but if you get injured, you risk holding back all progress.
Fix the wrist position, when it comes to the bench press, you are strongest when the wrists are supported – the wrists are usually the weakest point in the body. So while it may feel ‘more natural’ to bend the wrists back while benching, you are stronger and safer with straight wrists without twisting. Once you get used to this position, you will find that you can lift more weight with confidence.
Keeping the shoulder in the right position, it’s all about scapular retraction. This means pulling your shoulders down into the bench to create tension throughout your torso.
The shoulders should be in line with the elbows. This is how the pec muscles will be best activated. Also be aware of what the collarbone is doing, making sure it is moving naturally. You can also use the back arch — a powerlifting technique — as long as the shoulder blades are making contact and are therefore supported by the bench.
The position of the legs, it is included in almost every exercise. At the most basic level, the legs are supporting the rest of the body when you work your target muscles, so it’s a good idea to have a good idea of what they should be doing during the workout.
During the bench press, push the feet into the floor while raising the bar. This creates tension in the hamstrings and glutes, which helps stabilize the body. This is called leg drive. However, be careful not to lift the butt while attempting this. By the same token, you should use the legs to stabilize the entire body during a cable crossover or pectoral fly machine.
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