The muscle originating on the top surface of the eight or nine upper ribs is called the serratus anterior muscle. The serratus anterior muscle inserts at the medial border of the scapula, along the anterior length. Two slips of the serratus anterior muscle originate at the second rib. The serratus anterior muscle inserts exactly at the scapula, between the superior and inferior angles of the medial border. The parts of the serratus anterior muscle include three sections, the superior, intermediate or medial, and the inferior. The function of the serratus anterior muscle is to allow the anteversion of the arm and to pull the scapula forward, coming around the thorax. The serratus anterior muscle is an antagonist to the rhomboid muscles, as well as the synergist of the rhomboids. The scapula is able to move laterally due to the serratus anterior muscle, which is vital for the elevation of the arm. The serratus anterior muscle also allows the rotation of the arm upwards, which allows a human to lift items over his or her head.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Serratus anterior