Pecs 101: Overview, Anatomy, & Functions

Why do you need a Pecs 101?

Of all the muscles that we need to work on, most bodybuilders give more focus on the chest. The obsession in developing chest muscle probably boils down to the fact that it symbolizes masculinity and strength.

Having a well-developed chest is not that complicated. Before you can make your way through a thickly muscled chest, it’s important that you understand its structure and function first. Without proper knowledge and understanding, you may never get the result you want. In addition, injuries may happen if you are not familiar with your pectoral muscle.

Pecs 101: What is Pectoral Muscle?

Let’s start our Pecs 101 with an essential background. Popularly known as pecs, pectoral muscles are muscles that are located on the anterior chest wall. They span from just below the collar bone and extends through your top six ribs. They connect the front of your chest with the bones of your shoulder and upper arm.

Your pectoral muscles perform a complex set of functions, acting on both your shoulder joint and shoulder blades. Unlike most muscles, shoulder blades and shoulder joints can act in total isolation from each other. Your chest muscle serves as the primary movers to make the motion happen.

Most of these chest muscle movements involve pushing. For example, you use your pecs when you flex your shoulders and raise your arms over your head when you’re applying a deodorant. You also use your pecs when you press yourself up from the ground, hold a baby up overhead or push a bag of groceries. Pectoral muscles are active in these movements even though they are not exerting a lot of force. Along with your shoulder muscles and arms, your pecs are responsible for performing the “pushing” motion.

Pecs 101: Anatomy of Pectoral Region

Your pectoral muscles have four components – Pectoralis Major, Pectoralis Minor, Serratus Anterior and Subclavius. Each of these muscles serves unique functions. Let’s take a look at each muscle and see their functions and attachments.

1. Pectoralis Major

Pectoralis Major is the primary component of your chest. It is the largest and most superficial muscle amongst the four components. This thick, fan-shaped muscle makes up most of the bulk of the chest. The term Pectoralis Major came from the Latin word “pectoralis”  which means breast or chest and “major” which literally means big.

Origin and Location

The pectoralis major occupies the major portion of your chest. Its widest part originates at the breastbone or sternum and then attaches to the upper head of the humerus at your shoulder. The sternalis muscle arises from the surface of the pectoralis inserts into the deltoid muscle. Many people consider the sternalis muscle as the variant of the pectoralis major.

There are two main parts that make up the pectoralis major – the clavicular head and the sternocostal head. The clavicular head originates from the anterior of the medial half of the clavicle. The sternocostal head originates from the anterior portion of the sternum, the superior six costal cartilages and the aponeurosis of the external oblique.

Actions of Pectoralis Major

The sternocostal head is responsible for three major movements:

• Horizontal adduction – Pulling of your arm across your body such as exercising using a dumbbell fly.
• Shoulder extension – Pulling of the arm down from an overhead position.
• Internal rotation – Rotating the shoulder towards the front or midline of the body.

The clavicular head is responsible for flexing your arm at the shoulder joint. When both heads are working together, you can perform shoulder rotation and adduction.

2. Pectoralis Minor

The pectoralis minor may just be a relatively small muscle but you should never underestimate its importance.

Triangular in shape, the pectoralis minor is located in each side of the chest and situated directly under the pectoralis major. It originates from the third through fifth ribs and further extends diagonally up to the chest and attaches to your shoulder blade.

What Does the Pectoralis Minor Do?

Have you ever tried holding your breath underwater for as long as you could?

Before you took a plunge though, you must have taken a big, deep breath, right? You were able to make this big, deep breath partly because of the pectoralis minor muscle.

The main function of pectoralis minor is to move the scapula both downward and forward. Because of this movement, you maintain the mobility of your shoulder joint.

In addition, the pectoralis minor helps raise the third through fifth ribs. This expansion of the rib cage increases the capacity of your lungs.

3. Serratus Anterior

This fan-shaped muscle is located at the lateral wall of the thorax. The main part of the serratus anterior muscle lies deeply under the pectoral muscles and the scapula. It originates at the 1st to 9th rib and has its insertion at the ventral surface of the medial border of the scapula. It is divided into three parts:

• Superior part: 1st to 2nd rib; inserts at the superior angle of the scapula
• Intermedius part: 2nd to 3rd rib; inserts at the medial border of the scapula
• Inferior part: 4th to 9th rib; this is the most powerful and prominent part. It inserts at the medial border and inferior angle of the scapula.

Functions

This muscle allows the forward rotation of the arm. It’s also responsible for pulling the scapula forward and around the rib cage. This lateral movement of the scapula is important for the upward rotation of your arm, such as lifting an item over your head.

It also serves as an accessory to breathing. When your shoulder blade is in a fixed position, the serratus anterior spreads the ribs to support your breathing.

4. Subclavius

The subclavius muscle is located under the clavicle (popularly known as the collarbone). To search for this muscle, find the inner part of your collarbone with your fingers them move them just under your collarbone.

The origin of subclavius muscle is at the first rib. It begins in the area between the cartilage of the first rib and the bone. It then travels outward and inserts at the end surface of the middle part of the clavicle.

Its main function is to stabilize the clavicle in the sternoclavicular joint during arm and shoulder movement.

With this Pecs 101 article, you now understand the anatomy of the pectoral muscle and its function. How about we start creating an effective workout routine that targets this area?

REFERENCES:

Gamboa, P. (2015). Pectoralis Development Through Proper Biomechanics. Retrieved from https://www.bodybuilding.com/fun/issa17.htm

Jones, O. (2017). MUSCLES OF THE PECTORAL REGION. Retrieved from https://teachmeanatomy.info/upper-limb/muscles/pectoral-region/

Robertson, M. (2019). Pec Blastin’ 101: Building A Better Chest From Every Angle. Retrieved from https://www.bodybuilding.com/fun/pec-blastin-101-building-a-better-chest.html

Satterwhite, E. (2019). Harmony Of Structure & Function: The Pecs.Retrieved from https://www.bodybuilding.com/fun/satter16.htm