Maximus Gage
The pectoralis muscle, commonly referred to as pecs, is a group of skeletal muscles that connect the front of the human chest with the bones of the upper arm and shoulder. There are two such muscles on each side of the sternum (breastbone): the pectoralis major and the pectoralis minor. The pectoralis major is the larger and more superficial of the two, originating at the clavicle (collarbone), the sternum, the 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 (upper arm bone). The pectoralis minor lies underneath the pectoralis major, arising from the middle ribs and inserting into the scapula (shoulder blade).
| Characteristics | Values |
|---|---|
| Location | The pectoralis major is the largest muscle of the anterior chest wall. |
| Shape | The pectoralis major is a thick, fan-shaped muscle. |
| Position | The pectoralis major lies underneath the breast tissue and forms the anterior wall of the axilla. |
| Function | The pectoralis major brings the arms closer to the body, assists with moving the shoulders, and rotating the arms. |
| Blood Supply | The pectoral artery arises from the second branch of the axillary artery, the thoraco-acromial trunk. |
| Veins | The venous drainage is via the pectoral vein, draining into the subclavian vein. |
| Nerves | The medial pectoral nerve arises posterior to the axillary artery and pierces the pectoralis minor. |
| Tendons | The pectoralis major tendon is prone to rupture during exercises such as bench press. |
| Exercises | The pectoralis major is involved in exercises like the flat barbell bench press and the flat dumbbell bench press. |
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What You'll Learn
The pectoralis major is the largest muscle of the chest
The pectoralis major is the largest muscle in the chest. 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. There are two heads of the pectoralis major, the clavicular and the sternocostal, which reference their area of origin. The main function of this muscle is the adduction and internal rotation of the arm at the shoulder joint.
The pectoralis major muscle is a broad, superficial muscle found superficially in the anterior chest wall. In males, it is covered by a deep layer of fascia, subcutaneous tissue, and the adjacent skin. In females, it is covered by the breast. The deep surface of the muscle covers the pectoralis minor and serratus anterior muscles and the anterior surface of the upper six ribs. The pectoralis major is active in deep or forced inspiration but not expiration. When the diaphragm and intercostal muscles are insufficient for proper breathing, the scalenes, serratus, sternocleidomastoid, and pectoralis major can assist in inspiration.
The pectoralis major is a paired, superficial muscle located on the anterior surface of the thoracic cage. It is divided into three parts: the clavicular part, the sternocostal part, and the abdominal part. All three parts converge laterally and insert onto the greater tubercle of the humerus. The pectoralis major muscle is innervated by the lateral and medial pectoral nerves, which stem from the brachial plexus. The arterial supply of the pectoralis major, the pectoral artery, arises from the second branch of the axillary artery, the thoraco-acromial trunk. Its venous drainage is via the pectoral vein, draining into the subclavian vein.
The pectoralis major is the main muscle associated with the chest. It is the large muscle that can be seen from the outside. Its main action is to bring the arms closer to the body, but it also assists with moving the shoulders and rotating the arms. The pectoralis major is the biggest and strongest—and therefore the most important—of the chest muscles. The pectoralis minor lies underneath its larger counterpart muscle, the pectoralis major. Both muscles form part of the anterior wall of the axilla region.
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The pectoralis minor lies beneath the pectoralis major
The pectoralis muscle is located in the pectoral region on the anterior chest wall. The pectoralis major is the largest and most superficial muscle in the chest area. It is a thick, fan-shaped muscle that lies underneath the breast tissue. It is active in deep or forced inspiration, but not expiration.
The pectoralis major and minor are both part of the anterior wall of the axilla region. The axilla, or armpit, is the area between the side of the chest and the arm. The pectoralis major and minor are involved in the movement of the shoulder joint. The pectoralis major assists in flexion, adduction, and internal rotation of the humerus. It also assists in moving the shoulders and rotating the arms.
The pectoralis minor is an important muscle for shoulder movement, especially shoulder rotation. The medial pectoral nerve innervates the pectoralis minor. The nerve arises posterior to the axillary artery, pierces the pectoralis minor, and inserts into the posterior surface of the pectoralis major.
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The pectoralis major has two heads, the clavicular and the sternocostal
The pectoralis major is the superior 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 two heads of the pectoralis major have different nervous supplies. The clavicular head derives its nerve supply from the lateral pectoral nerve, which arises from the lateral cord of the brachial plexus. The medial pectoral nerve innervates the sternocostal head. The lateral pectoral nerve arises posterior to the axillary artery, pierces the pectoralis minor near the midclavicular line, and enters the muscle medial to the humeral insertion.
The function of the pectoralis major is dependent on which heads of muscles are involved. The clavicular head assists in flexion of the arm, while the sternocostal head assists in extension of the arm at the glenohumeral joint. The pectoralis major also assists in moving the shoulders and rotating the arms.
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The pectoralis major is active during deep inspiration
The pectoralis major is the largest muscle in the chest. It is a thick, fan-shaped muscle that lies underneath the breast tissue in females and the deep layer of fascia, subcutaneous tissue, and skin in males. The pectoralis major is the most superficial muscle in the pectoral region.
The pectoralis major has three parts: the clavicular part, the sternocostal part, and the abdominal part. All three parts converge laterally and insert onto the greater tubercle of the humerus. The main function of the pectoralis major is the adduction and internal rotation of the arm in the shoulder joint. Acting independently, 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 with moving the shoulders and rotating the arms.
The pectoralis major can be targeted with various exercises, including the barbell bench press, dumbbell bench press, and machine bench press, which induce high activation in the sternocostal region.
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The pectoralis region includes the serratus anterior muscle
The main part of the serratus anterior lies deep to the scapula and the pectoral muscles and is easily palpable between the pectoralis major and latissimus dorsi muscles. The serratus anterior muscle pulls the scapula forward around the thorax, allowing for anteversion and protraction of the arm. It also rotates the scapula, allowing the arm to be raised over 90 degrees.
The serratus anterior is innervated by the long thoracic nerve, a branch of the brachial plexus. Damage to this nerve can lead to functional loss of the serratus anterior, resulting in difficulty elevating the arm and an unstable shoulder. This condition is known as scapular winging, where the scapula is no longer held against the chest wall.
The pectoralis region, located on the anterior chest wall, contains four muscles that exert a force on the upper limb: the pectoralis major, pectoralis minor, serratus anterior, and subclavius. The pectoralis major is the largest and most superficial muscle in the pectoral region, lying underneath the breast tissue. It has two heads, the clavicular and the sternocostal, which reference their area of origin. The pectoralis minor lies underneath the pectoralis major and assists in shoulder movement, especially rotation.
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Frequently asked questions
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 minor is a thin, triangular muscle located beneath the pectoralis major. It attaches to the ribs and serves to stabilise the scapula, the large bone of the shoulder.
The pectoralis major serves to flex, extend, and rotate the humerus, the long bone of the upper arm. It is also active during deep or forced inspiration.
