Anatomy, Thorax, Serratus Anterior Muscles

The serratus anterior is a fan-shaped muscle that originates on the superolateral surfaces of the first to eighth ribs or the first to ninth ribs at the lateral wall of the thorax and inserts along the superior angle, medial border, and inferior angle of the scapula. The main part of the serratus anterior lies deep to the scapula and the pectoral muscles and is easily palpated between the pectoralis major and latissimus dorsi muscles. This large muscle is generally divided into three distinct parts according to the points of insertion: serratus anterior superior (insertion near the superior angle), serratus anterior intermediate (insertion along the medial border), and serratus anterior inferior (insertion near the inferior angle).