Shoulder trapezius muscle bulge, there are hard knots to consider is poor posture, muscle spasm, cervical spine problems and so on. 1. Poor posture: long-term work at work can cause injury to the trapezius muscle, localized tissue swelling and bulging. Long-term use of pillows of inappropriate height can cause muscle imbalance in the neck and shoulders, which can also lead to bulges and hard knots in the trapezius muscle area. 2. Muscle spasms: excessive strain on the neck and shoulders, cold muscles, etc. can cause the trapezius muscle to become tense and spastic, resulting in localized bumps and hard knots. 3. Cervical spine problems: such as cervical spine degeneration, cervical spine physiological curvature changes, will cause muscle tension, spasm. There may be other reasons for shoulder trapezius muscle bulge and hard knots, it is recommended to go to the hospital in time to improve the examination and clarify the cause.