Scapula(paired):The scapula is an irregularly shaped bone, that is very thin and fragile. It articulates with the Humerus and with your clavicle . Your scapula is almost completely surrounded by muscle, and this makes it very movable.
Your clavicle is known more commonly as your collar bone, and there are are two, left and right. Each articulates with your scapula and your sternum. The clavicle is the bone that connects all of your arm bones, and your scapula, with the rest of your skeleton. So when any force hits your arm or your shoulder, it travels through your clavicle and dissipates throughout the rest of your skeleton. Because of this, it is the most commonly broken bone.
Tim D. White, 1991. Human Osteology.
White, Tim D. and Pieter A. Folkens, 2005. The Human Bone Manual. Elsevier