The shoulder is a very mobile joint. It is built this way to enable us to function efficiently using our upper limbs, equipped with opposable thumbs, to their maximum capability. It allows us to reach high behind our back or perform overhead activity with control and accuracy. The fact that the shoulder joint is so mobile makes it inherently unstable and thus vulnerable to injury. To counter this instability it has a system of both passive and active stabilisers. The passive stabilisers (ligaments) of the joint act at the end of range and are responsible for restriction of excessive movement. These ligaments are often damaged when the shoulder is dislocated. The active stabilisers (rotator cuff) of the shoulder act to keep the ball centrally located in the socket so that the movement is smooth and controlled and not overpowered by the larger muscles during movement. Dysfunction of these muscles often results in pathology to other structures in the shoulder.
Some of the common shoulder injuries that you may have heard include:
Rotator Cuff pathology
Acromioclavicular (AC) joint pain