Sudden numbness in the little finger of the left hand is often due to peripheral nerve injury. The nerves in the hand innervate the median nerve, ulnar nerve and radial nerve, and the ulnar nerve innervates the sensation in the little finger and ring finger near the little finger side, which can cause numbness in the little finger when the ulnar nerve is injured. The most common injury to the little finger is elbow canal syndrome, which is caused by trauma to the elbow joint or frequent activity at the elbow joint, resulting in narrowing of the elbow canal and compression of the ulnar nerve, and narrowing of the carpal ulnar canal at the wrist can also lead to numbness in the little finger. Nerve root compression in the cervical 8 thoracic 1 segment caused by cervical spondylosis can also cause numbness in the little finger of the left hand. In addition, it is also necessary to be alert to the presence of a heart attack, and some patients with heart disease also show symptoms of numbness in the hand. It is important to develop good habits and avoid prolonged elbow flexion and wrist flexion causing nerve entrapment symptoms. If the pinky numbness is prolonged, it is recommended to go to the hospital for systematic examination to clarify the cause of the injury. If sudden onset of pinky numbness is accompanied by symptoms of chest tightness and chest pain, it is recommended to immediately stop the activity and contact emergency services, which may be a symptom of heart attack.