There are 12 thoracic vertebra in the spine, labelled T1-T12 from top to bottom. T4 syndrome is the name given to irritation that occurs most commonly at the level of T4, however irritation may also occur from T2-T7. The exact cause of T4 syndrome is unknown, however it is believed that poor movements and poor posture that occur around the level of T4 affect the surrounding structures. T4 syndrome typically presents as upper back stiffness with associated symptoms of upper extremity pain, numbness and/or paraesthesia. There may also be an association with headaches and migraines.