The muscle next to the neck is called the sternocleidomastoid muscle, which is the largest muscle in the neck and is found on both sides, with one end connected to the mastoid process and one end connected to the head of the sternum and the head of the clavicle, hence the name sternocleidomastoid. The role of the sternocleidomastoid muscle can make the neck turn to the left and to the right, while maintaining the head in an upright and forward position. If the sternocleidomastoid muscle becomes diseased or if there is an internal mass, it may cause a sternocleidomastoid, especially in newborns, mostly due to birth injuries, but also after intrauterine compression. If the swollen nodules cannot be palpated, but the hard mastoid muscle can be palpated, ultrasound examination of the muscle is needed to further clarify the situation, and massage therapy can be used to treat the problem.