Final answer:
The coracobrachialis muscle flexes and adducts the arm, sharing this action with two other muscles: the pectoralis major and the latissimus dorsi. These muscles have convergent fascicles that unite at a common attachment site, enabling coordinated movement.
Step-by-step explanation:
Three of the muscles that move the arm have the action of flexing and adducting. The coracobrachialis muscle is one of them, and it performs this function by extending over a broad area with convergent fascicles that converge on a common attachment site. However, this muscle is specifically known for its role in flexing and adducting the arm. The other two muscles that share this action are the pectoralis major and the latissimus dorsi. The pectoralis major is a thick, fan-shaped muscle that covers the superior portion of the anterior thorax and contributes to arm flexion. Similarly, the latissimus dorsi, which is found on the lower back, also participates in adduction and medial rotation due to its broad, triangular shape and location.