Final answer:
The pectoral girdle, which attaches the upper limbs to the axial skeleton, consists of the clavicle and the scapula. The clavicle is a horizontally positioned bone that braces the shoulder, while the scapula connects to the humerus to form the shoulder joint.
Step-by-step explanation:
The pectoral girdle is a critical structure in the human body that serves to attach the upper limbs to the axial skeleton. It primarily consists of two bones on each side of the body: the clavicle, commonly referred to as the collarbone, and the scapula, better known as the shoulder blade. The clavicle is an S-shaped bone that is positioned horizontally between the ribcage (sternum) and the scapula, providing structural support and functioning as a brace for the shoulder. The scapula is a flat, triangular-shaped bone that sits posteriorly (on the back side) to the ribcage and provides the point of articulation for the humerus (the bone of the upper arm) to form the shoulder joint.
Together, the clavicle and scapula enable a wide range of movements for the upper limbs and support the muscles responsible for these movements.