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The pectoralis major is the largest muscle of the anterior chest wall. It is a thick, fan-shaped muscle that lies underneath the breast tissue and forms the anterior wall of the axilla. Its origin lies on the anterior surface of the medial half of the clavicle, the anterior surface of the sternum, the first 7 costal cartilages, the sternal end of the sixth rib, and the aponeurosis of the external oblique of the anterior abdominal wall. The pectoralis major is active in deep or forced inspiration, but not expiration. It is also essential for performing any sort of pushing motion, like when trying to open a heavy door or do a push-up. The pectoralis major is not considered breast tissue, though it may be referred to colloquially as pecs or chest muscle.
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What You'll Learn
- The pectoralis major is the largest muscle of the anterior chest wall
- The pectoralis major lies underneath the breast tissue
- The pectoralis major has two heads: the clavicular and the sternocostal
- The pectoralis major is active during deep inspiration
- The pectoralis major is involved in flexion, adduction and internal rotation of the humerus
The pectoralis major is the largest muscle of the anterior chest wall
The pectoralis major has several important functions, including flexion, adduction, and medial rotation of the arm at the glenohumeral joint. It also plays a role in stabilising the scapula by drawing it anteroinferiorly against the thoracic wall. The muscle receives dual innervation from the medial and lateral pectoral nerves, which supply the sternocostal and clavicular heads, respectively. Maximal activation of the pectoralis major occurs in the transverse plane through pressing motions.
Exercises that focus on the pectoralis major often involve pressing movements, such as the flat barbell bench press or flat dumbbell bench press. In these exercises, the individual lies supine on a bench with their feet flat on the ground and uses either a barbell or dumbbells to extend their arms towards the nipple line before bringing the weights up to arm's length. Dumbbell flyes, performed on an incline bench, are another effective exercise for targeting the pectoralis major.
While the pectoralis major is typically well-developed in individuals who engage in weight training or similar activities, it can be absent in rare cases due to congenital abnormalities such as Poland Syndrome. This condition can result in the unilateral absence of the pectoralis major, sometimes accompanied by the absence of the breast in females. In such cases, surgical implants may be available to modify aesthetic contours, mass, and asymmetry.
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The pectoralis major lies underneath the breast tissue
The pectoralis major is the thick, fan-shaped or triangular convergent muscle of the human chest. It is the largest and most superficial muscle in the chest area. The pectoralis major lies underneath the breast tissue and forms the anterior wall of the axilla. The breast is anchored to the pectoralis major by suspensory ligaments of Cooper, which traverse throughout the breast tissue from the dermis of the skin down to the pectoralis fascia. The pectoralis major has two heads, the clavicular and the sternocostal, which reference their area of origin. The muscle is active in deep or forced inspiration, but not expiration.
The pectoralis major is responsible for four actions, which are primarily responsible for the movement of the shoulder joint. Firstly, it flexes the humerus, as in throwing a ball underhand or lifting a child. Secondly, it adducts the humerus, as when flapping the arms. Thirdly, it rotates the humerus medially, as occurs when arm-wrestling. Fourthly, the pectoralis major is responsible for keeping the arm attached to the trunk of the body. The two heads of the pectoralis major have different nervous supplies. The clavicular head derives its nerve supply from the lateral pectoral nerve, while the sternocostal head is innervated by the medial pectoral nerve.
The pectoralis major is frequently utilised in reconstructive plastic surgery as it can provide good muscle coverage for a breast implant. It is also important to identify the pectoralis major during breast surgery to avoid damage to the nerve, which can result in denervation and atrophy or fibrosis of the muscle. The pectoral muscle is considered part of the breast, and adequate surgical therapy of posterior breast masses involving the pectoral muscle will need to include some muscle in the excision.
There are many exercises that focus on the pectoralis major, including pressing exercises such as the flat barbell bench press and the flat dumbbell bench press. These exercises involve an individual lying supine on a bench with feet flat on the ground, extending their arms slowly towards the nipple line, and then bringing the weights up over their face at arm's length.
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The pectoralis major has two heads: the clavicular and the sternocostal
The pectoralis major is the superior most and largest muscle of the anterior chest wall. It is a thick, fan-shaped muscle that lies underneath the breast tissue and forms the anterior wall of the axilla. The pectoralis major is the most superficial muscle in the pectoral region.
The clavicular part is close to the deltoid muscle and contributes to flexion, horizontal adduction, and inward rotation of the humerus. When at an approximately 110-degree angle, it contributes to adduction of the humerus. The sternocostal part is antagonistic to the clavicular part, contributing to the downward and forward movement of the arm and inward rotation when accompanied by adduction. The sternal fibres can also contribute to extension, but not beyond anatomical position.
The pectoralis major is considered part of the breast, and adequate surgical therapy of posterior breast masses involving the pectoral muscle will need to include some muscle in the excision.
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The pectoralis major is active during deep inspiration
The pectoralis major is a thick, fan-shaped muscle that makes up the bulk of the chest muscles. It is the most superficial muscle in the chest area and is located on the anterior surface of the thoracic cage. In males, it is covered by the deep layer of fascia, subcutaneous tissue, and the adjacent skin. In females, it is covered by the breast. The pectoralis major muscle is also referred to as the "pecs" or "chest muscle".
The pectoralis major has two heads: the clavicular and sternocostal. The clavicular head originates from the anterior surface of the medial half of the clavicle, while the sternocostal head originates from the anterior surface of the sternum and the anterior aspects of the costal cartilages of ribs 1-6. The muscle fibres from both heads run laterally, converging towards the proximal humerus.
The pectoralis major is active during deep or forced inspiration, but not expiration. It assists in elevating the thorax during forced inspiration. When acting together with the latissimus dorsi muscle, the pectoralis major pulls the trunk forwards or upwards, which is important in activities such as climbing.
The pectoralis major is involved in various exercises, such as pressing exercises like the flat barbell bench press and flat dumbbell bench press. These exercises help to strengthen the pectoralis major and are commonly performed by individuals who want to develop their "pecs".
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The pectoralis major is involved in flexion, adduction and internal rotation of the humerus
The pectoralis major is a thick, fan-shaped or triangular convergent muscle of the human chest. It is the largest and most superficial muscle in the chest area. The pectoralis major is also referred to as the "pecs" or "chest muscle". It is located on the anterior surface of the thoracic cage, underneath the breast tissue in females and the deep layer of fascia, subcutaneous tissue, and skin in males. The pectoralis major has two heads: the clavicular and the sternocostal, which reference their area of origin.
The pectoralis major has four actions that are primarily responsible for the movement of the shoulder joint. The first of these actions is flexion of the humerus, which occurs in activities such as throwing a ball underhand or lifting a child. The second action is adduction of the humerus, which occurs when flapping the arms. The third action is medial rotation of the humerus, which occurs during arm-wrestling. The fourth action is keeping the arm attached to the trunk of the body.
The two heads of the pectoralis major have different functions. The clavicular part is close to the deltoid muscle and contributes to flexion, horizontal adduction, and inward rotation of the humerus. When the arm is at an approximately 110-degree angle, the clavicular part contributes to adduction of the humerus. The sternocostal part is antagonistic to the clavicular part, contributing to downward and forward movement of the arm and inward rotation when accompanied by adduction. It also facilitates the extension of the flexed arm by pulling it downwards.
The pectoralis major is involved in various exercises, such as the flat barbell bench press and the flat dumbbell bench press. In these exercises, the individual lies supine on a bench with their feet flat on the ground and uses either a barbell or a pair of dumbbells to extend their arms, lowering the weight slowly towards the nipple line, and then bringing it back up.
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Frequently asked questions
The pectoralis major is the largest muscle of the anterior chest wall. It is a thick, fan-shaped muscle that lies underneath the breast tissue and forms the anterior wall of the axilla.
The pectoral muscle is considered part of the breast. However, muscle tissue is completely different from breast tissue. Working on your pecs may increase the size of your chest muscles but will not change your actual breast tissue.
The pectoral muscles are essential for performing any sort of pushing motion, like opening a heavy door or doing a push-up. They also play a role in deep breathing, especially the pectoralis minor.
Some common exercises that focus on the pectoral muscles include the flat barbell bench press and the flat dumbbell bench press.
