The great serratus anterior ???????? one of my favorite muscle. The serratus anterior is a muscle that originated on the surface of the upper right ribs at the chest and inserts along the entire anterior length of the medial border of the scapula. It’s occasionally called “boxer’s muscles” because it’s largely responsible for the protraction of the scapula. That is, pulling the scapula (shoulder blade) forward and around the rib cage. The serratus anterior also helps to stabilize the scapula, in addiction it assists in rotating the scapula upward. It is right there can you see ? It looks like teeth ????