What are the main muscles for shoulder stretching?

Deltoid, pectoralis major, teres major, latissimus dorsi, coracoid and biceps brachii.

1. deltoid muscle, commonly known as "Tiger Head Muscle", is a triangular muscle with the bottom up and the tip down. It is located under the shoulder skin and wraps the shoulder joint from the front, back and outside. It is a multi-feathered muscle. The protruding shape of the shoulder is formed by this muscle. The muscle bundle is divided into three parts: anterior, middle and posterior.

2. The pectoralis major is located in the shallow layer of the anterior upper part of the chest.

3. teres major is located on the lower side of teres minor, and its lower edge is covered by the upper edge of latissimus dorsi. The whole muscle is columnar, starting from the back of the lower angle of the scapula, and the muscle bundle is concentrated outward and upward, ending at the crest of the humeral tubercle.

4. latissimus dorsi is the largest latissimus dorsi muscle in the whole body, located under the skin of the back and posterolateral chest. It is a right triangle, and the upper part of the inside is covered by trapezius muscle. The aponeurosis originates from the spinous process of the lower six thoracic vertebrae, all spinous processes of the lumbar vertebrae and the posterior lip of the external iliac crest 1/3.

5. The short head of coracoid muscle and biceps brachii both starts from the tip of coracoid process, descends along the medial side of biceps brachii, and ends at the midpoint of the medial edge of humerus. This muscle is also innervated by the musculocutaneous nerve, which is the flexor and adductor of the shoulder-brachial joint. This kind of muscle injury sometimes leads to coracoid process avulsion fracture. It is innervated by musculocutaneous nerve (neck 5 ~ 7).

Extended data:

Distribution of some movements: The movements of glenohumeral joint include flexion, extension, adduction, abduction, internal rotation and external rotation.

1, flexion: the flexion of the shoulder joint is mainly completed by the fibers in the front of deltoid, clavicle of pectoralis major, coracoid process and biceps brachii, among which the fibers in the front of deltoid are the most obvious.

2. Postextension: The muscles of shoulder extension mainly include the posterior deltoid fiber, latissimus dorsi, pectoralis major rib, teres major and the long head of triceps brachii, among which the posterior deltoid fiber plays the most important role.

3. adduction: There are mainly pectoralis major, teres major, latissimus dorsi, coracoid process and biceps brachii, and the fibers before and after deltoid muscle are also adducted.

4. Abduction: The abduction of shoulder joint is completed by deltoid muscle (mainly its intermediate bundle) and supraspinatus muscle. The deltoid muscle is the main abductor when the shoulder is in the internal rotation or external rotation position, and the abductor muscle strength is stronger when the shoulder is rotated externally.

5. Internal rotation: Internal rotation muscle is mainly subscapular muscle. When the shoulder joint is in a specific position, the fibers in front of the deltoid muscle of pectoralis major, teres major and latissimus dorsi also have a certain internal rotation.

6. External rotation: The external rotation muscles of the shoulder joint include infraspinatus, teres minor and the fibers behind the deltoid muscle.

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