Which statement about the sternocostal head of the pectoralis major is true?

Which statement about the sternocostal head of the pectoralis major is true?

• A. Flexes the humerus from a flexed position
• B. Extends from a flexed position
• C. Abducts the scapula
• D. Elevates the clavicle

Answer: (B)

The sternocostal head of the pectoralis major can extend the arm from a flexed position. This part originates from the sternum and upper costal cartilages and inserts on the humerus. When the arm is already flexed (raised in front), contracting this head pulls the humerus backward toward the body, effectively extending the arm back from its flexed posture. That contrasts with the clavicular head, which is more involved in flexing the arm from a neutral position. The sternocostal head also handles adduction and medial rotation, but its ability to bring a flexed arm into extension is the key reason this statement is true. It does not elevate the clavicle or abduct the scapula.

The sternocostal head of the pectoralis major can extend the arm from a flexed position. This part originates from the sternum and upper costal cartilages and inserts on the humerus. When the arm is already flexed (raised in front), contracting this head pulls the humerus backward toward the body, effectively extending the arm back from its flexed posture. That contrasts with the clavicular head, which is more involved in flexing the arm from a neutral position. The sternocostal head also handles adduction and medial rotation, but its ability to bring a flexed arm into extension is the key reason this statement is true. It does not elevate the clavicle or abduct the scapula.