Which structures are responsible for the attachment of the arm to the torso?

The pectoral girdle is responsible for the attachment of the arm to the torso. This structure comprises the clavicles (collarbones) and the scapula (shoulder blades). The pectoral girdle plays a critical role in providing the necessary support and mobility for the arms, allowing for a wide range of motion while connecting the upper limbs to the axial skeleton.

In contrast, the costal margin refers to the lower edge of the thoracic cavity formed by the ribs, which does not provide direct attachment for the arms. The temporal and orbital structures relate to the skull and the eye socket, respectively, and are not involved in the connection between the arms and the torso. Therefore, the pectoral girdle is the only option that directly fulfills the function of attaching the upper limbs to the body.