Up to 20% of the adult population experiences shoulder symptoms at any one time. Shoulder pain is the second most common musculoskeletal condition in the upper extremities. Shoulder pain can often be interrelated with neck pain. It has been shown that neck and shoulder pain may arise from the C5/C6 facet joints, neck pain and headaches from the C2/C3 facet joints.
The sensory innervations of facet joints is derived from the medial branch of the posterior primary division (dorsal ramus) at both the level of the joint and the levels immediately above and below the joint. These multilevel innervations may explain why pain from a facet joint has a broad referral pattern.
In experiments evaluating the distribution of pain from the cervical facet joint, C5/C6 facet joints were identified. A needle was then inserted until it was felt to pierce the joint capsule and injected contrast medium until pain was elicited. The subject was then examined for tenderness in the cervical and shoulder region. The distribution of evoked pain and tenderness was marked on the skin and the area recorded on a body diagram. It was found that the pain patterns for C5/C6 covered the shoulder above the level of the spine of the scapula. Following this, the medial branches of the dorsal rami of the target joint were injected with local anesthetic and noted that the experimentally induced pain was relieved in all subjects.
The study demonstrated the cervical facet joints can be a source of neck pain and that the pain extends beyond the immediate vicinity of the stimulated joint to include an element of referred pain into the related limb or limb girdle.
