The infraspinatus muscle is part of the human rotator cuff, and its main function is the internal and external rotation movement of the upper arm. It generally manifests as localized pain, activity limitation, localized striated nodules and other manifestations. 1. Localized pain: generally in the infraspinatus fossa and humeral tuberosity, which may radiate to the top of the head, limitation of shoulder activities, and severe limitation of posterior extension and supination activities. 2. Pathologic signs: pain in the supraspinatus muscle in the internal retracted position of resistance, pain in external rotation, as well as severe pain in the infraspinatus muscle during stretching. 3. Pathologic nodules: multiple painful nodules or strips can be palpated at the origin of infraspinatus, and painful nodules can also be palpated at the greater tuberosity of the humerus. 4. Activity limitation: after 90° abduction of the upper limb, the palm of the hand is downward, horizontal backward extension, and pain in the posterior part of the shoulder. Injury of infraspinatus muscle needs to look at the clinical symptoms on the one hand, but also need to be combined with the imaging examination, must be in the regular medical unit for consultation.