Which two surfaces are designed for articulation with the CA humeral head?

The correct answer indicates that the glenoid and acromion are the two surfaces designed for articulation with the humeral head. In a total shoulder arthroplasty, the primary articulating surface is the glenoid, which is the socket of the shoulder joint where the humeral head—a ball-like structure at the top of the humerus—fits. The glenoid’s design allows for a significant range of motion in the shoulder while providing stability for the joint.

While the acromion is part of the scapula and plays a role in shoulder mechanics, it does not directly articulate with the humeral head. Instead, it serves as a bony prominence that can affect the range of motion and the mechanics of the shoulder, particularly in relation to the rotator cuff and impingement.

The other combinations of structures, such as the scapula and clavicle or the coracoid and acromion, involve bones that are related to the shoulder complex but do not have a direct articulating relationship with the humeral head during shoulder movement. Therefore, understanding the relationships within the shoulder joint is critical in recognizing the functional anatomy during arthroplasty procedures.