Describe the origin and insertion of serratus anterior and its primary actions on the scapula.

• A. Origin: outer surfaces of ribs 1-8 (or 1-9). Insertion: anterior surface of the medial border of the scapula. Actions: protracts the scapula and holds it against the thoracic wall; upwardly rotates the scapula.
• B. Origin: scapula; Insertion: medial border; Actions: retraction.
• C. Origin: ribs 9-12; Insertion: inferior angle of scapula; Actions: depresses scapula.
• D. Origin: vertebrae; Insertion: medial border of scapula; Actions: retracts and upwardly rotates.

Answer: (A)