Dominic Stone
The pectoral muscles, commonly known as pecs, are the muscles that connect the front of the human chest with the bones of the upper arm and shoulder. The pectoral region contains four muscles: the pectoralis major, pectoralis minor, serratus anterior, and subclavius. The pectoralis major is the most prominent muscle in the region, and it, along with the pectoralis minor, is responsible for adducting the arms, or pulling them towards the midline of the body. The pectoralis minor, which lies beneath the pectoralis major, assists in depressing and spreading the shoulder blades and can aid in breathing. The serratus anterior is located laterally in the chest wall and allows the arm to be raised over 90 degrees. The subclavius is a small muscle located underneath the clavicle that provides protection to the underlying neurovascular structures.
| Characteristics | Values |
|---|---|
| Location | Anterior chest wall |
| Number of muscles | 4 |
| Names of muscles | Pectoralis major, pectoralis minor, serratus anterior, subclavius |
| Shape of pectoralis major | Thick, fan-shaped or triangular convergent |
| Shape of pectoralis minor | Thin, triangular |
| Pectoralis major composition | Two heads: clavicular and sternocostal |
| Clavicular head origin | Anterior surface of the medial clavicle |
| Sternocostal head origin | Anterior surface of the sternum, superior six costal cartilages, and the aponeurosis of the external oblique muscle |
| Pectoralis minor origin | Margins of the third to fifth ribs adjacent to the costochondral junction |
| Serratus anterior function | Rotates the scapula, allowing the arm to be raised over 90 degrees |
| Serratus anterior attachments | Originates from the outer surface of the first to eighth ribs and inserts into the costal aspect of the medial margin of the scapula |
| Subclavius location | Directly underneath the clavicle, running horizontally |
| Subclavius function | Offers minor protection to underlying neurovascular structures |
| Subclavius attachments | Originates from the junction of the first rib and its costal cartilage, inserts onto the inferior surface of the middle third of the clavicle |
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What You'll Learn
- The pectoralis major is the thicker, fan-shaped muscle that makes up the bulk of the chest muscle
- The pectoralis minor is a thin, triangular muscle located beneath the pectoralis major
- The subclavius muscle is a small muscle located directly underneath the clavicle
- The serratus anterior is a thin muscular sheet originating from the outer surface of the first to eighth ribs
- The function of the pectoral muscles is to adduct the arms, or pull them towards the midline of the body
The pectoralis major is the thicker, fan-shaped muscle that makes up the bulk of the chest muscle
The pectoralis major is responsible for flexing, extending, and rotating the humerus, the long bone of the upper arm. It also plays a role in adduction, bringing the arms towards the body's midline. The tension in the pectoralis major muscle can affect the tone and function of the upper limb. Various exercises can be performed to target the pectoralis major, 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 weights to work the muscle.
The pectoralis major is also associated with certain medical conditions. For example, Poland syndrome is a congenital unilateral deficiency in the pectoralis major muscle that can present with cosmetic, cardiopulmonary, or other issues. Additionally, trigger points in the pectoralis major muscle can produce symptoms similar to those of a heart attack or angina pectoris, including pain in the chest, front of the shoulder, inside of the arm, and inside of the elbow.
Overall, the pectoralis major is a crucial muscle in the pectoral region, responsible for various movements of the upper limb and contributing to the aesthetic appearance of the chest.
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The pectoralis minor is a thin, triangular muscle located beneath the pectoralis major
The pectoralis region is located on the anterior chest wall and contains four muscles that exert force on the upper limb: the pectoralis major, pectoralis minor, serratus anterior, and subclavius. The pectoralis major is a thick, fan-shaped or triangular convergent muscle that makes up the bulk of the chest muscle. It lies under the breast and serves to flex, extend, and rotate the humerus, the long bone of the upper arm.
The pectoralis minor is thinner and less prominent than the pectoralis major, residing below it. It is a small muscle that lies beneath the pec major. Despite sitting at the front of the body, the pectoralis minor controls structures associated with the backside. In addition to its attachment to the ribs, the pectoralis minor affixes at the coracoid process, a small, hook-shaped protrusion atop the scapula or shoulder blade.
The pectoralis minor helps depress and spread apart the shoulder blades and can assist with breathing. It is challenging to isolate the pectoralis minor in exercises as it is not a prime mover. However, it is engaged during upper-body exercises where the body leans forward and the shoulder blades are drawn downward.
The pectoralis muscles, or "pecs," are the muscles that connect the front of the human chest with the bones of the upper arm and shoulder. The primary function of the pectoral muscles is to adduct the arms, or pull them towards the midline of the body from various angles.
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The subclavius muscle is a small muscle located directly underneath the clavicle
The pectoral region is located on the anterior chest wall and contains four muscles: the pectoralis major, pectoralis minor, serratus anterior, and subclavius. These muscles are responsible for exerting force on the upper limb, allowing for movement and providing stability.
The subclavius muscle is a small, short, and triangular muscle located directly underneath the clavicle, or collarbone. It runs horizontally between the first rib and its costal cartilage, inserting onto the middle third of the clavicle. The main function of the subclavius muscle is to actively stabilize the clavicle at the sternoclavicular joint during movements of the shoulder and arm. By contracting, it depresses the sternal end of the clavicle, preventing its dislocation and protecting the underlying neurovascular structures, such as the brachial plexus and subclavian vessels, from potential injury in the event of a clavicular fracture.
The subclavius muscle also contributes to the control of the scapula's position in relation to the thorax through its lateral aponeurotic extension and fascial connections. While its contraction may not significantly impact the distance between the sternoclavicular and acromioclavicular joints, it is hypothesized to regulate the output of kinetic energy during the upper extremity's movement.
In summary, the subclavius muscle, located beneath the clavicle, plays a crucial role in stabilizing the clavicle and protecting the neurovascular structures beneath it. Additionally, it influences the positioning of the scapula and potentially modulates the kinetic energy output during arm movements.
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The serratus anterior is a thin muscular sheet originating from the outer surface of the first to eighth ribs
The pectoral, or "pec", 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 provide movement to the upper limbs or ribs: the pectoralis major, pectoralis minor, serratus anterior, and subclavius.
The serratus anterior is a thin, fan-shaped muscle that originates from the outer surface of the first to eighth ribs at the lateral wall of the thorax. It is inserted along the superior angle, medial border, and inferior angle of the scapula. The serratus anterior normally originates by nine or ten muscle slips, arising from either the first to eighth ribs, or the first to ninth ribs. Two slips usually arise from the second rib, making the number of slips greater than the number of ribs from which they originate.
The serratus anterior acts to pull the scapula forward around the thorax, rotating the scapula and allowing the arm to be raised over 90 degrees. It is also a key scapular stabiliser, keeping the shoulder blades against the ribcage when at rest and during movement. The muscle is divided into three parts according to the points of insertion: the serratus anterior superior, which is inserted near the superior angle; the serratus anterior intermediate, which is inserted along the medial border; and the serratus anterior inferior, which is inserted near the inferior angle.
The serratus anterior is occasionally called the "big swing muscle" or "boxer's muscle" because it is largely responsible for the protraction of the scapula, or the pulling of the scapula forward and around the rib cage that occurs when someone throws a punch.
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The function of the pectoral muscles is to adduct the arms, or pull them towards the midline of the body
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. This region contains four muscles that provide movements to the upper limbs or ribs: the pectoralis major, pectoralis minor, serratus anterior, and subclavius.
The pectoralis major is a thick, fan-shaped or triangular convergent muscle, which makes up the bulk of the chest muscle. It lies under the breast and serves to flex, extend, and rotate the humerus, the long bone of the upper arm. The primary function of the pectoralis major is to adduct the arms, or pull them towards the midline of the body from various angles. This muscle is also involved in pressing and swinging movements, such as pressing a loaded barbell or swinging open a heavy door.
The pectoralis minor is a thin, triangular muscle located beneath the pectoralis major. It attaches to the ribs and serves to stabilize the scapula, the large bone of the shoulder. The pectoralis minor helps depress (pull down) and spread apart the shoulder blades, and can assist with breathing. This muscle works whenever the pecs are engaged, so it can be difficult to isolate during exercise.
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, and protracts the scapula, holding it against the ribcage.
The subclavius is a small muscle located directly underneath the clavicle, running horizontally. It affords some minor protection to the underlying neurovascular structures and anchors and depresses the clavicle.
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Frequently asked questions
Pec muscles, or pectoral muscles, 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 thicker and larger of the two chest muscles. 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 helps to stabilise the scapula, the large bone of the shoulder.
