Back muscles are mainly superficial back muscles and deep back muscles, as follows: First, superficial back muscles: superficial back muscles such as rhomboid, latissimus dorsi, scapular raphe, rhomboid, etc. The rhomboid muscle is pulling the scapula towards the midline, the upper muscle fibers can lift the scapula, while the lower muscle fibers will lower the scapula, mainly innervated by the paraspinal nerve. The latissimus dorsi muscle is mainly responsible for posterior extension, internal extension and internal rotation of the shoulder joint and is innervated by the thoracic dorsal nerve. The scapularis raphe is primarily used to elevate the scapula and is innervated by the dorsal scapular nerve. The rhomboid muscle is to lift and pull the scapula internally, also innervated by the dorsal scapular nerve. Second, the deep back muscles: the deep back muscles mainly include the erector spinae and the entheses, the erector spinae is to extend the spine, tilt the head, innervated by the posterior spinal nerve branch, the entheses are mainly unilateral contraction to turn the head to the same side, bilateral contraction at the same time will make the head tilt back, innervated by the posterior branch of the cervical nerve.