There are many reasons for pain in the left lower arm, such as cervical spondylosis, peripheral nerve injury, rheumatism and so on. If the pain in the left arm cannot be relieved for a long time, you should go to a professional hospital in time for further examination to clarify the cause of the disease and avoid delaying the condition. Left arm pain may be caused by cervical spondylosis. Both nerve root and spinal cord cervical spondylosis may cause nerve compression, and if it happens to compress the nerves related to the left small arm, it will cause pain in the left small arm. Left lower arm pain can also be related to peripheral nerve compression, such as the ulnar nerve and median nerve, which are located in the left lower arm. Left arm pain can also be caused by rheumatoid arthritis, rheumatoid arthritis pain is often manifested as wandering, multiple arthritis, when the involvement of the left arm joints will appear left arm pain. Related patients are advised to seek timely medical treatment and targeted treatment.