Final answer:
The sternoclavicular joint is the articulation between the sternal end of the clavicle and the sternum, while the acromioclavicular joint is the articulation between the acromial end of the clavicle and the scapula's acromion, both playing important roles in shoulder mobility and stability.
Step-by-step explanation:
The sternoclavicular and acromioclavicular are joints relating to the clavicle. The sternoclavicular joint is where the sternal (medial) end of the clavicle meets the manubrium of the sternum, providing the only bony connection between the upper limb's pectoral girdle and the axial skeleton. It allows for significant movement of the clavicle and scapula with the support of the costo- ("rib") clavicular ligament. In contrast, the acromioclavicular joint is formed where the acromial (lateral) end of the clavicle meets the acromion of the scapula, enabling the motion at the shoulder. This joint's stability is bolstered by the coracoclavicular ligament, which connects the lateral end of the clavicle to the coracoid process of the scapula.