Damage to the rotator cuff. The so-called rotator cuff is made up of four muscles and their tendons surrounding the shoulder-scapular joint, keeping it in the correct position. When performing monotonous, repetitive activities (e.g. with hands above the head, such as when hanging curtains or playing volleyball), these structures are overloaded, and even broken (most often the supraspinatus tendon is damaged).
The frequent causes of rotator cuff damage are injuries, even minor ones (e.g. sudden jerking while driving a tram). The most common manifestation of rotator cuff tears is shoulder pain, especially when lifting the arm or placing a hand on the back. Pain is often located in the anterior and lateral area of the shoulder it may occur at night and prevent sleeping on an occupied shoulder.
Trunk space syndrome. The sub-shoulder space is located under the shoulder process, and the bursae located there allow smooth movement of the articular structures while lifting the arm. If there is “tightness” in the subacromial space, eg as a result of inflammation of the bursa or the formation of bone spurs, the movement of the humerus from sliding under the shoulder process is blocked; then severe pain is felt, most severe at the abduction in the range of 60–110 ° (the so-called painful arch).