The main causes of radiating pain in the back of the left shoulder may be the following: 1, for cervical spondylosis, its stimulation of the nerve roots will also cause radiating pain in the back of the shoulder, the patient has a positive pressure neck test during the examination, and it radiates to the left upper limb and the back of the left shoulder. 2, some non-specific heart infarction can also cause radiating pain in the left shoulder, in the above case, you need to go to the hospital to check the ultrasound of the heart, or special examination, etc. to prevent the occurrence of heart infarction. In addition, some diseases of the visceral system, such as cholecystitis or pancreatitis, can also cause radiating pain in the back of the shoulder, which is a kind of involvement pain, not related to local pain, but is actually a disorder of the visceral nerves, which leads to the pain of inaccurate nerve positioning. In case of the above mentioned pain, it is important to go to the hospital first and have the appropriate tests done to prevent some important diseases from being missed.