The pectoralis minor muscle is located in the anterior aspect of the chest or thoracic wall, and is one of the most superficial muscles there. It is triangular in shape and is located under the pectoralis major, and both form the anterior wall of the axilla. The muscle arises from the anterior surface of the third to fifth ribs adjacent to the costochondral junction, and the fibers pass upward and laterally to insert into the medial border and superior surface of the coracoid process of the scapula. The primary actions of this muscle include the stabilization, depression, abduction or protraction, internal rotation, and downward rotation of the scapula. The pectoralis minor muscle creates a passage between the ribs for the transit of the brachial plexus and both the subclavian artery and vein. If the muscle is shortened or tight, this abnormal tension can negatively affect the Scapulohumeral Rhythm and can also cause thoracic outlet syndrome.