The pectoral girdle includes the shoulder made up of which two bones?

The pectoral girdle, also known as the shoulder girdle, is composed of two primary bones: the clavicle (collarbone) and the scapula (shoulder blade). These bones work together to provide attachment points for the upper limbs to the axial skeleton, allowing for a wide range of motion and flexibility in the shoulder region.

The clavicle serves as a strut that connects the arm to the body and helps to stabilize the shoulder. The scapula, on the other hand, provides a surface for the attachment of several muscles that are crucial for shoulder movement, such as the rotator cuff muscles. This anatomical arrangement allows for the complex movements of the arm, including lifting and reaching.

In contrast, the other options include bones that do not belong to the pectoral girdle. The humerus is the bone of the upper arm and connects to the scapula at the shoulder joint but is not part of the girdle itself. The radius and ulna are bones of the forearm and are unrelated to the structural composition of the pectoral girdle. Thus, the connection between the clavicle and scapula is essential for the function and stability of the shoulder.