The shoulder is one of two pairs of ball-and-socket joints in the body (the other set is located in the hip). Because of its complex anatomy, the shoulder has the greatest range of mobility compared to any other joint in the body (Beltran et al., 2003). Unfortunately, this greater mobility results in diminished stability. Two mechanisms contribute to the joint’s stability:

• The tendon of the long head of the biceps

• The rotator cuff muscles and tendons

• The size and shape of the glenoid fossa

• The labrum

• The joint capsule

• The glenohumeral ligaments (Beltran et al, 2003)

Because of this combination of high mobility and low stability, there is an increased risk of pathology, which explains why the shoulder is the most dislocated joint in the body.

Shoulder pain can originate from myriad causes, including not only intrinsic disease and dysfunction in the structures around the joint but also referrals from related areas such as the cervical spine, thorax, and soft tissue structures.

Shoulder dysfunction accounts for about 5% of visits to primary care physicians and is the third most common musculoskeletal complaint (Wilson, 2005). Assessment of shoulder dysfunction can be difficult in part because of the sophisticated interaction between the shoulder complex and other areas of the body. Shoulder injuries can arise from both traumatic and chronic overuse conditions, and they can be exacerbated by underlying postural concerns that lead to a predisposition to re-injury. While not comprehensive, this chapter addresses the complex components in order to provide an understanding of the overall functioning of the region. The chapter reviews basic anatomy and then moves into other areas, including:

• Specific bony landmarks that mark important areas for palpation

• Soft tissue structures, including muscles of the region

• Movements of the region

• Manual muscle tests for the shoulder

• Dermatome and trigger-point referral patterns for the involved muscles