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The pectoral muscles, also known as pecs, are the muscles that connect the front of the human chest with the bones of the upper arm and shoulder. This region contains four muscles: the pectoralis major, pectoralis minor, serratus anterior, and subclavius. The pectoralis major is the largest muscle of the anterior chest wall and is involved in deep or forced inspiration. It is also commonly targeted in pressing exercises such as the flat barbell bench press and the flat dumbbell bench press. The pectoralis minor lies underneath the pectoralis major and stabilises the scapula. The serratus anterior rotates the scapula, allowing the arm to be raised over 90 degrees. Lastly, the subclavius affords minor protection to the underlying neurovascular structures.
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What You'll Learn
The pectoralis major is the largest muscle in the pectoral region
The pectoralis major serves several important functions. It is responsible for flexing, extending, and rotating the humerus, the long bone of the upper arm. This muscle also plays a role in breathing, assisting in deep or forced inspiration when the diaphragm and intercostal muscles are insufficient for proper ventilation. Additionally, the pectoralis major is involved in shoulder movements, and its trigger points can produce symptoms similar to those associated with a heart attack or angina pectoris.
Due to its size, location, and blood supply, the pectoralis major has clinical significance in neck surgery and breast surgery. In neck surgery, the muscle can be used in flap repairs for soft tissue reconstruction following trauma or tumour-related operations. In breast surgery, such as mastectomy and breast augmentation, knowledge of the anatomy of the pectoralis major is crucial to avoid damaging the nervous supply of the muscle, which can result in denervation, atrophy, or fibrosis.
The pectoralis major is also targeted in various exercises, particularly pressing exercises such as the flat barbell bench press and the flat dumbbell bench press. These exercises involve lying supine on a bench with the feet flat on the ground and extending the arms using weights. By strengthening the pectoralis major, individuals can improve their upper body strength and stability.
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The pectoralis minor lies underneath the pectoralis major
The pectoralis muscle is a group of muscles in the pectoral region that connects the front of the human chest with the bones of the upper arm and shoulder. The pectoralis major is the largest and most superficial muscle in the chest area. It is a thick, fan-shaped or triangular convergent muscle that makes up the bulk of the chest muscles. It lies under the breast and serves to flex, extend, and rotate the humerus, the long bone of the upper arm.
The pectoralis minor also has clinical significance and is used as a surgical landmark due to the structures that lie below or deep to the muscle and its tendon. The medial pectoral nerve and the lateral pectoral nerve penetrate the pectoralis minor muscle to innervate it. The vascular supply to the pectoralis minor comes from the thoracoacromial artery and the superior thoracic artery.
Together, the pectoralis major and minor form the anterior wall of the axilla or armpit, along with the subclavius muscle. The subclavius muscle is located directly underneath the clavicle and provides minor protection to the underlying neurovascular structures. The serratus anterior is located more laterally in the chest wall and forms the medial border of the axilla region. It rotates the scapula, allowing the arm to be raised over 90 degrees.
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The subclavius muscle forms the armpit
The pectoral region is located on the anterior chest wall and 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 most superficial muscle in the pectoral region, lying underneath the breast, and making up the bulk of the chest muscle. 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 subclavius muscle is a small, short, and triangular muscle that forms part of the pectoral region. It is located directly underneath the clavicle, running horizontally. The subclavius originates from the junction of the first rib and its costal cartilage and inserts onto the inferior surface of the middle third of the clavicle. The tendon spreads superolaterally into a muscle belly that inserts into the lower surface of the middle third of the body of the clavicle.
The subclavius muscle is enclosed by the clavipectoral fascia, a fibrous connective tissue that spans the interval between the clavicle and pectoralis minor muscle. The main function of the subclavius is to actively stabilise the clavicle at the sternoclavicular joint during movements of the shoulder and arm. It anchors and depresses the clavicle, preventing injuries to the adjacent neurovascular structures in the event of a fractured clavicle.
Thus, the subclavius muscle, along with the pectoralis major and pectoralis minor, forms the axilla or armpit.
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The serratus anterior holds the scapula against the ribcage
The pectoral muscles are those that connect the front of the human chest with the bones of the upper arm and shoulder. The pectoral region contains four muscles that exert a force on the upper limb: the pectoralis major, pectoralis minor, serratus anterior, and subclavius.
The serratus anterior also acts with the upper and lower fibres of the trapezius muscle to sustain upward rotation of the scapula, allowing for overhead arm movement. It is an accessory inspiratory muscle, used in respiratory distress, and lifts the ribcage, thus supporting breathing.
The serratus anterior is innervated by the long thoracic nerve. Damage to this nerve can weaken or even paralyse the serratus anterior, leading to scapular winging, where the scapula is no longer held against the ribcage and protrudes out of the back.
Weakness in the serratus anterior can be identified through the serratus wall test. To perform this test, stand about 2 feet from a wall, facing it. Place both hands on the wall with your shoulders elevated to about 90 degrees and perform a push-up. Have someone watch the position of your shoulder blades. If one shoulder blade wings out, there may be weakness in your serratus anterior on that side.
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The pectoral region contains four muscles that exert force on the upper limb
The pectoral region is located on the anterior chest wall and contains four muscles that exert force on the upper limb. These muscles are the pectoralis major, pectoralis minor, serratus anterior, and subclavius. Together, they provide movements to the upper limbs or ribs.
The pectoralis major is the largest and most superficial muscle in the pectoral region. 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 has two heads, the clavicular and the sternocostal, which reference their area of origin. The function of the pectoralis major is threefold and dependent on which heads of muscles are involved. It provides flexion, adduction, and medial rotation of the arm at the glenohumeral joint. It also assists in deep or forced inspiration during breathing. The pectoralis major is active in a variety of exercises, particularly pressing exercises such as the flat barbell bench press and the flat dumbbell bench press.
The pectoralis minor lies underneath the pectoralis major and forms part of the anterior wall of the axilla region. It originates from the 3rd to 5th ribs and inserts into the coracoid process of the scapula. The pectoralis minor stabilizes the scapula by drawing it anteroinferiorly against the thoracic wall.
The serratus anterior is located more laterally in the chest wall and forms the medial border of the axilla region. It consists of several strips of muscles that originate from the lateral aspects of ribs 1-8 and attach to the costal surface of the medial border of the scapula. The serratus anterior rotates the scapula, allowing the arm to be raised over 90 degrees. It also protracts the scapula, holding it against the rib cage.
The subclavius is a small muscle located directly underneath the clavicle, running horizontally. It provides minor protection to the underlying neurovascular structures. The subclavius originates from the junction of the 1st rib and its costal cartilage and inserts onto the inferior surface of the middle third of the clavicle. It functions to anchor and depress the clavicle. Along with the pectoralis major and pectoralis minor, the subclavius forms the axilla or armpit.
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Frequently asked questions
The pectoral muscles, or "pecs", are the muscles that connect the front of the human chest with the bones of the upper arm and shoulder.
There are four muscles in the pectoral region: pectoralis major, pectoralis minor, serratus anterior, and subclavius.
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. It serves to flex, extend, and rotate the humerus, the long bone of the upper arm.
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.
Many exercises focus on the pectoralis muscle, including pressing exercises such as the flat barbell bench press and the flat dumbbell bench press.
