In general, subscapularis muscle injury can be manifested as obvious pain in front of the shoulder joint, aggravated pain in external rotation position and reduced pain in internal rotation position, obvious limitation of back movement of the affected limb of the shoulder joint, shoulder rotation, internal retraction and other movements are affected, and pain in the scapula with localized compression pain and percussion pain, and so on. The subscapularis muscle is the largest and strongest muscle in the rotator cuff muscle group, located in front of the scapula, and is triangular in shape. Starting from the subscapular fossa, the muscle bundle goes upward through the anterior aspect of the scapular joint and ends at the humeral tuberosity. Its role is to rotate the shoulder joint internally and ensure the stability of the shoulder joint anteriorly. The subscapularis muscle is often damaged suddenly due to the sudden internal contraction and internal rotation of the upper limb, or due to the long-term continuous internal contraction and internal rotation of the upper limb back and forth for many times of contraction and diastole caused by the starting and stopping point of tendon fibers and small blood vessel damage. Once the subscapularis muscle injury, the affected limb should be immediately braked and promptly consult the doctor to clarify the condition and then carry out targeted treatment.