Dominic Stone
The pectoral muscles, commonly referred to as pecs, are a vital component of the human body's upper body musculature. They are composed of two muscles on each side of the body: the pectoralis major and pectoralis minor. These muscles are responsible for various movements, including pushing, lifting, and stabilising the shoulders and arms. The pectoralis major is a large, fan-shaped muscle with two heads—the clavicular head and the sternal head—that originate from different parts of the chest and converge to form the bulk of the muscle. On the other hand, the pectoralis minor is a smaller, triangular muscle that sits beneath the pectoralis major and assists in stabilising the scapula. Strong pectoral muscles are essential for upper body strength and posture, and their health is critical for orthopedic well-being.
| Characteristics | Values |
|---|---|
| Number of pectoral muscles | 2 |
| Names | Pectoralis Major, Pectoralis Minor |
| Location | Beneath the breast tissue, across the upper part of the chest |
| Function | Adduction of the arm, pulling them towards the midline of the body, pushing, lifting, stabilising the shoulders and arms |
| Appearance | Thick, fan-shaped |
| Composition | Three segments: clavicular part, sternocostal part, coastal part |
| Exercises | Bench presses, push-ups, cable flies, pec deck flies |
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What You'll Learn
The pectoralis major
The main function of the pectoralis major is the adduction and internal rotation of the arm at the shoulder joint. The clavicular part helps to flex the extended arm up to 90 degrees, while the sternocostal part facilitates the extension of the flexed arm by pulling it downwards. The pectoralis major also assists in ventilation by lifting the rib cage during inhalation when the scapula is fixed, aiding in breathing. It is active in deep or forced inspiration but not expiration. When the diaphragm and intercostal muscles are insufficient for proper breathing, the pectoralis major can assist in inspiration.
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The pectoralis minor
The pectoralis muscle is one of the muscles that connect the front walls of the chest with the bones of the upper arm and shoulder. There are two pectoralis muscles on each side of the sternum (breastbone): the pectoralis major and the pectoralis minor.
The primary nerve supply to the pectoralis minor muscle comes via the medial pectoral nerve (C8, T1), a minor branch of the brachial plexus that arises from the cervical portion of the spinal cord. Innervation to the pectoralis minor is also received from the lateral pectoral nerve via a communicating branch known as the 'ansa pectoralis'. The vascular supply to the pectoralis minor comes from several sources, including the thoracoacromial artery, superior thoracic artery, and lateral thoracic artery.
A shortened pectoralis minor can cause issues such as pain and restriction in neck movements, stiffness and pain in the upper back, and an increased risk of rotator cuff pathologies. It can also cause thoracic outlet syndrome by impinging on the brachial plexus and axillary blood vessels, leading to shoulder impingement.
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Shoulder stability
The pectoralis muscles are essential for the dynamic movement and stability of the shoulder girdle. The pectoralis major and minor muscles underpin the movement and stability of the anterior thoracic wall and shoulder girdle. The pectoralis major is the largest muscle of the anterior chest wall, while the pectoralis minor is a thin, triangular muscle lying beneath the pectoralis major.
The pectoralis major originates at the clavicle (collarbone), sternum, ribs, and a tendinous extension of the external oblique abdominal muscle. It extends across the upper part of the chest and is attached to a ridge at the rear of the humerus. Its major actions include adduction or depression of the arm and rotation of the arm forward about the axis of the body. The pectoralis major also assists in pulling the trunk up when the arms are raised and fixed, as in mountain climbing.
The pectoralis minor extends from the third to fifth ribs to the coracoid process of the scapula, influencing scapular depression and protraction, crucial for respiration and shoulder function. It aids in drawing the shoulder forward and downward. The pectoralis minor also plays a vital role in stabilising and moving the scapula.
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Orthopedic health
The pectoralis major is a large muscle in the upper chest, connecting the front walls of the chest with the bones of the upper arm and shoulder. It is the muscle that creates the bulk of the chest, and it arises from the clavicle (collarbone), sternum, ribs, and a tendinous extension of the external oblique abdominal muscle. The pectoralis major is responsible for controlling the movement of the arm, with its contractions pulling on the bone of the upper arm to create lateral, vertical, or rotational motion. It also plays a part in deep inhalation, pulling the ribcage to create room for the lungs to expand.
Additionally, orthopedic surgeons may address aesthetic concerns related to the pectoralis major. For example, submuscular and intramuscular surgical implants can modify aesthetic contours, mass, and asymmetry in both males and females. In some cases, the absence of the pectoralis major muscle may result in a noticeable asymmetrical configuration of the chest wall, as seen in a case study of a 22-year-old marine. However, this congenital absence did not cause functional loss in ordinary activities, as other surrounding muscles compensated.
To maintain orthopedic health, it is important to be mindful of the risks associated with certain activities. For instance, injuries to the pectoralis major can occur during weightlifting and bodybuilding exercises that place excessive strain on the shoulders and chest. Understanding the anatomy, physiology, and surgical considerations of the pectoralis muscle is crucial for achieving optimal outcomes and avoiding complications.
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Exercises to target the pectoral muscles
The pectoral muscles are those that connect the front walls of the chest with the bones of the upper arm and shoulder. There are two such muscles on each side of the sternum (breastbone) in the human body: the pectoralis major and the pectoralis minor. The pectoralis major is the larger of the two and is attached to a ridge at the rear of the humerus (the upper arm bone). The pectoralis minor lies beneath the pectoralis major, arising from the middle ribs and inserting into the scapula (shoulder blade).
To strengthen the muscles in the pectoral region, it is recommended to include a variety of exercises in your workout routine. Here are some exercises that specifically target the pectoral muscles:
Compound Pressing Exercises
These exercises are fundamental for building overall chest strength. They include bench presses and push-ups, which primarily target the pectoralis major and also engage supporting muscles like the deltoids and triceps. By adjusting the angle of the press (flat, incline, or decline), you can emphasise different areas of the pectoralis major, focusing on the upper, middle, or lower fibres.
Isolation Exercises
These exercises focus specifically on the pectoralis major by directly targeting the muscle fibres and reducing the involvement of other muscle groups. Examples include cable flies and pec deck flies.
Barbell Presses
This exercise involves overloading the pecs with weight and is often followed by exercises that cross over the midline, such as dumbbell flies and cable crossovers.
Incline Dumbbell Bench Press
This exercise targets the upper pecs. To perform it, lie on an inclined bench, holding a dumbbell in each hand with a neutral grip, and place your feet firmly on the ground. Use the strength of your upper chest to thrust your arms upward, bringing the dumbbells down towards your chest and squeezing the pecs as you lower them.
Decline Barbell Bench Press
This exercise targets the lower pecs, also known as the sternal head of the pectoralis major.
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Frequently asked questions
The pectoral muscles, commonly referred to as pecs, are a vital component of the upper body musculature. There are two types of pectoral muscles: the pectoralis major and the pectoralis minor.
The pectoralis major is the largest muscle of the anterior chest wall. It is responsible for movements such as horizontal adduction (bringing the arms across the chest) and internal rotation of the shoulder. It also assists in pulling the trunk up during mountain climbing.
The pectoralis minor is a thin, triangular muscle that lies beneath the pectoralis major. It plays a vital role in stabilizing and moving the scapula. It aids in drawing the shoulder forward and downward.
To strengthen the pectoral muscles, you must include a variety of exercises such as compound pressing exercises (e.g. bench presses, push-ups) and isolation exercises (e.g. cable flies, pec deck flies). These exercises target the pectoralis major and supporting muscles, enhancing upper-body performance and improving shoulder stability.
