Running between the front of your shoulder joint and your breast bone (sternum), this bone has two joints at either end.
And like any other joint it can be damaged, often by a forceful movement or impact, such as in contact sports and falls. In some cases the joint may actually break causing one end or the other to pop out in a painful bulge.
Movements will be painful raising your arm all the way up or when pulling your straight arm across the body towards the opposite shoulder. The pain can be felt in either joint: where it joins with your breast bone or around the top of your shoulder - nearer to the edge than the neck.
Except in severe injuries involving total rupture of ligaments, osteopathic treatment aims to re-position the bone within the joint and to reduce spasm which can cause extra muscular tension around the bone and joints, making the pain worse. And if you've hurt it in a fall or shoulder charge, then chances are that it'll be more than the clavicle that will need attention.
In the older patient, a dull, constant pain, possible with painful clicking can mean that arthritis is making itself felt. This can also hurt at night when lying on the affected side puts more pressure on the A/C joint.