👉 The term "sternomastoid" refers to a group of muscles that are located at the base of the neck, typically around the collarbone. These muscles include the Sternocleidomastoidea (SCM), which is responsible for moving the upper arms and shoulders up and down. The Sternocleidomastoideus (SCM) muscle is also known as the Sternocleidomastoid muscle and is responsible for moving the jaw, chin, and neck
