The muscle behind the clavicle should refer to the trapezius muscle, for the back of the neck and neck, generally innervated by the 11th pair of parasympathetic brain nerves, if the trapezius muscle is stiff, the patient can take massage, massage and other methods to make the muscle relax. The trapezius muscle is located in the subcutaneous part of the neck and back, one side is triangular, the left and right sides of the synthetic rhomboid, the main function is to pull the scapula to the spine, the upper fibers lift up the scapula, the lower fibers down the scapula, but also the scapula and the base of the skull and the vertebrae are connected together to play the role of suspending the scapula. The trapezius muscle is generally innervated by the 11th pair of parasympathetic cerebral nerves and the anterior branches of the third and fourth cervical nerves, and the supplying artery is the transverse carotid artery, as well as a number of other minor secondary arteries, which return mainly through the transverse jugular vein and the suprascapular vein to the external jugular vein and the subclavian vein. The muscle behind the clavicle should refer to the trapezius muscle. If the trapezius muscle is stiff, appropriate methods can be taken to relax the muscle, such as shoulder acupressure, massage, hot compresses and so on.