The pectoral girdle on both the side is composed of two bones: clavicle and scapula, it is the clavicle joint only which is connected to the rest of skeleton by a small joint (the sternoclavicular joint). The acromioclavicular joint is more smaller joint that connects both the bones of the girdle together. The coracoclavicular ligament (strongest ligament in the upper limb) is a strong ligament that connects clavicle to the scapula, and the clavicle is attached to the 1st costal cartilage by the costoclavicular ligament.

 

Forces of the upper limb are transmitted to the axial skeleton by clavicle via costoclavicular ligament and sternoclavicular joint.