Logan Steele
The upper extremity muscles, also known as the upper limb muscles, are those that attach the scapula to the thorax and generally move the scapula, those that attach the humerus to the scapula and generally move the arm, and those located in the arm or forearm that move the forearm, wrist, and hand. The muscles of the upper limb can be divided into six different regions: pectoral, shoulder, upper arm, anterior forearm, posterior forearm, and hand. Upper limb muscles are responsible for climbing, lifting, and manipulating objects, and they can be classified by origin, topography, function, or innervation.
| Characteristics | Values |
|---|---|
| Upper limb muscles | Pectoral, shoulder, upper arm, anterior forearm, posterior forearm, and the hand |
| Pectoral muscles | Pectoralis major, pectoralis minor, serratus anterior, and subclavius |
| Shoulder muscles | Trapezius, serratus anterior, supraspinatus, infraspinatus, teres minor, subscapularis |
| Upper arm muscles | Biceps, triceps |
| Forearm muscles | Flexor carpi ulnaris, flexor digitorum profundus, extensor digitorum communis, palmaris longus |
| Upper limb injuries | Tennis elbow, golfers elbow, fractures, soft tissue injuries, tendon tears |
| Upper limb nerves | Musculocutaneous nerve, median nerve, ulnar nerve, axillary nerve, radial nerve, dorsal scapular nerve, long thoracic nerve, suprascapular nerve |
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What You'll Learn
- Muscles that move the scapula and attach it to the thorax
- Muscles that move the arm and attach the humerus to the scapula
- Muscles in the forearm that move the forearm, wrist and hand
- Muscles that move the shoulder, including the trapezius and serratus anterior
- Muscles in the pectoral region, including pectoralis major and pectoralis minor
Muscles that move the scapula and attach it to the thorax
The scapula, or shoulder blade, is a flat, triangular bone located at the back of the trunk. It provides a point of attachment for a number of muscles that make up the arm and shoulder. The scapula moves freely across the posterior thoracic wall, allowing the arm to move with it and providing a wide range of movement and mobility for the upper limb.
The muscles that attach the scapula to the thorax and generally move the scapula are known as extrinsic muscles. These include the triceps, biceps, and deltoid. The triceps, for example, originate from the torso and attach to the bones of the shoulder. The deltoid muscle allows for flexion and medial rotation (anterior fibres), abduction (middle fibres), extension and lateral rotation (posterior fibres) at the shoulder joint.
The third group of muscles includes the levator scapulae, trapezius, rhomboids, and serratus anterior. These muscles are responsible for rotational movements and stabilization of the scapula. The serratus anterior, rhomboids, and trapezius muscles, for instance, are involved in the elevation of the scapula. The serratus anterior and trapezius muscles are also responsible for upward rotation.
The scapula allows for full function of the shoulder joint, one of the most mobile and versatile joints in the human body. The scapula engages in six types of motion, including protraction, retraction, elevation, depression, upward rotation, and downward rotation. These motions allow for a full range of motion of the upper extremity.
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Muscles that move the arm and attach the humerus to the scapula
The upper limb comprises several muscles that are organised into anatomical compartments. These muscles act on the various joints of the hand, arm, and shoulder, providing stability and allowing fluid movement. The muscles that attach the humerus to the scapula and generally move the arm are known as scapulohumeral muscles. These include the rotator cuff muscles, which provide stability to the glenohumeral joint. The supraspinatus, infraspinatus, subscapularis, and teres minor form a musculotendinous cuff around the glenohumeral joint. The subscapularis attaches to the middle part of the scapula and stretches to the bottom of the ball of the humerus. The supraspinatus stretches from the top of the scapula to the top of the humerus.
The teres minor attaches to the side of the scapula and the humerus beneath the infraspinatus. The deltoid muscle, located on the outside of the shoulder, also plays a role in moving the arm in different directions. The rhomboids, consisting of two muscles, stretch from the top of the spine to the scapula and assist in lifting the shoulder blade. The trapezius, a large triangular muscle at the back of the shoulder, helps with lifting and lowering the shoulder.
The serratus anterior is another muscle that attaches the scapula to the thorax and generally moves the scapula. It is involved in upward rotation, allowing for the full function of the shoulder joint. The scapula must upwardly rotate, posteriorly tilt, and externally rotate to achieve full elevation of the arm. The serratus anterior muscle is crucial for this movement, working in conjunction with other muscles and bones, including the clavicle and humerus, in a 2:1 ratio.
The scapula, or shoulder blade, is a sturdy, flat, triangular bone that connects the clavicle to the humerus. It provides attachment points for various muscle groups, including intrinsic and extrinsic muscles. The intrinsic muscles of the scapula include the rotator cuff muscles, teres major, subscapularis, teres minor, and infraspinatus. The extrinsic muscles include the triceps, biceps, and deltoid. The levator scapulae, trapezius, rhomboids, and serratus anterior are part of a third group of muscles that contribute to rotational movements and stabilisation of the scapula.
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Muscles in the forearm that move the forearm, wrist and hand
The muscles of the upper limb can be divided into six different regions: pectoral, shoulder, upper arm, anterior forearm, posterior forearm, and hand. The forearm is the section of the upper limb from the elbow to the wrist, and its bony structure is formed by the radius and ulna.
The forearm muscles are divided into two categories: intrinsic and extrinsic muscles. The intrinsic muscles function to move the forearm by pronating and supinating the radius and ulna. The extrinsic muscles flex and extend the digits of the hand. The forearm muscles are contained in two main compartments: anterior (front) and posterior (rear).
The anterior compartment has three layers of muscle: superficial, intermediate, and deep. The muscles in the anterior compartment help turn the forearms and bend or flex the wrist and fingers. The superficial muscles in the anterior compartment are the flexor carpi ulnaris, palmaris longus, flexor carpi radialis, and pronator teres. The deep anterior forearm muscles include the flexor digitorum profundus, flexor pollicis longus, and pronator quadratus. The pronator quadratus is a square-shaped muscle that allows you to turn your forearm downward and helps extend or straighten your fingers and wrists.
The brachioradialis muscle traverses the elbow joint, running from the arm to the wrist, and helps flex the elbow. It also helps you turn your arm. The extensor carpi radialis longus and extensor carpi radialis brevis extend the wrist and move the hand away from the direction of the thumb. The extensor digitorum splits into four tendons and connects to the finger joints, helping to straighten or extend the fingers. The extensor carpi ulnaris helps turn and extend the wrist. The anconeus, near the top of the superficial layer, helps extend the forearm at the elbow.
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Muscles that move the shoulder, including the trapezius and serratus anterior
The upper limb can be divided into six different regions: pectoral, shoulder, upper arm, anterior forearm, posterior forearm, and hand. The shoulder joint, also known as the glenohumeral joint, has the most extensive range of motion in the human body. The muscles of the shoulder play a critical role in providing stability to the joint.
The trapezius is a large triangular muscle at the back of the shoulder. It helps lift and lower the shoulder. The muscle is divided into three parts: descending (superior), ascending (inferior), and middle. The trapezius contributes to scapulohumeral rhythm through attachments on the clavicle and scapula, and to head balance through muscular control of the cervical spine. It is also used for active movements, such as side bending and turning the head, elevating and depressing the shoulders, and internally rotating the arm. The upper trapezius is frequently involved in neck injuries.
The deltoid muscle is the primary muscle for shoulder abduction and works closely with the trapezius for arm elevation. The deltoid initiates the movement, while the trapezius stabilizes and rotates the scapula to allow a full range of motion.
The serratus anterior originates on the upper ribs and inserts along the medial border of the scapula. It plays a crucial role in protracting and stabilizing the scapula against the rib cage. The serratus anterior works in conjunction with the lower trapezius to rotate the scapula upward during arm elevation, allowing the arm to lift smoothly above shoulder height. It also prevents scapular winging, ensuring efficient shoulder movement, especially during pushing or punching actions.
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Muscles in the pectoral region, including pectoralis major and pectoralis minor
The upper limb comprises many muscles, which are organised into six different regions: the pectoral, shoulder, upper arm, anterior forearm, posterior forearm, and the hand. The pectoral 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 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. There are two heads of the pectoralis major: the clavicular and the sternocostal, which reference their area of origin. The clavicular head originates from the anterior surface of the medial clavicle, while the sternocostal head originates from the anterior surface of the sternum, the superior six costal cartilages, and the aponeurosis of the external oblique muscle. The upper and lower fibres of the pectoralis major insert into the crest of the greater tubercle of the humerus. The two heads of the pectoralis major have different nervous supplies, with the clavicular head deriving its nerve supply from the lateral pectoral nerve.
The pectoralis minor lies underneath its larger counterpart muscle, the pectoralis major. It arises as three separate heads from the anterior surface of the 3rd, 4th, and 5th ribs near the corresponding costal cartilages, as well as the fascia overlying the adjacent intercostal muscles found in the intercostal spaces. The pectoralis minor extends superolaterally to form a flat tendon, which inserts into the medial border and coracoid process of the scapula. The pectoralis minor muscle is one of the most superficial muscles on the anterior aspect of the chest or thoracic wall. Together with the pectoralis major, subclavius, and serratus anterior, it forms part of the anterior axioappendicular (thoracoappendicular) muscles.
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, which 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 muscle rotates the scapula, allowing the arm to be raised over 90 degrees.
The subclavius is a small muscle located directly underneath the clavicle, running horizontally. It affords some minor protection to the underlying neurovascular structures. It 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. The function of the subclavius is to anchor and depress the clavicle.
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Frequently asked questions
Upper extremity muscles are those that attach the scapula to the thorax, attach the humerus to the scapula, and those located in the arm or forearm that move the forearm, wrist, and hand.
The muscles that move the shoulder and arm include the trapezius and serratus anterior.
The muscles of the pectoral region include the pectoralis major, pectoralis minor, serratus anterior, and subclavius.
The muscles of the shoulder joint can be divided into an intrinsic and extrinsic group. The extrinsic group originates from the torso and attaches to the bones of the shoulder, while the intrinsic group originates from the bones of the shoulder and attaches to the humerus.
Lateral epicondylitis (tennis elbow) is caused by inflammation of the common extensor origin due to repetitive or sustained contraction of the extensor muscles of the forearm. Medial epicondylitis (golfer's elbow) is caused by inflammation of the common flexor origin due to repetitive or sustained contraction of the flexor muscles of the forearm.
