The shoulder joint is unique among the body's joints in that it relies heavily upon the muscle groups in the region to actually hold the joint together. This lack of major bone and ligament support allows for the greatest freedom of arm movement. But it also requires the muscles to function properly for the joint to work effectively and stay healthy. As such, perhaps no joint in the body is affected as much by trigger points as the shoulder (glenohumeral) joint. Of all the muscle groups that act on the shoulder joint, the rotator cuff muscles are the most important.
The rotator cuff muscle group is composed of the following muscles:
The Teres Minor These are small muscles that are easily overloaded by sporting and repetitive activities. Trigger points can cause chronic tension in these muscles, making them more likely to suffer tears. Trigger points in any of the muscles that attach to the shoulder blade can also play a significant role in shoulder dysfunction disorders. It is very important to address these trigger points, as they distort the proper movement of the shoulder blade during movements of the arm. Shoulder pain is a complex disorder that can involve more than ten muscle groups. Clinical experience has shown that the following three muscle groups are involved most often: The Infraspinatus, Subscapularis, Trapezius.
The Infraspinatus Trigger Points that Cause Shoulder Pain The Infraspinatus muscle is found on the back of the shoulder blade and is one of the Rotator Cuff muscles. It attaches to the lower part of the shoulder blade and runs laterally to attach to the top of the upper arm bone (the humerus). Contraction of this muscle rotates the arm in the shoulder joint and stabilizes the shoulder joint during other movements. Trigger points in this muscle produce pain in the shoulder joint that radiates down the front and side of the arm. Clients with active Infraspinatus trigger points are unable to reach behind their back, and have difficulty combing their hair or brushing their teeth.
Infraspinatus Trigger Point Symptoms Clients with active infraspinatus trigger points will present with pain that is felt deep within the shoulder joint. The deep nature of the pain convinces many clients that they have damage in the joint itself. The pain will often extend down the front of the upper arm, and in athletes it can mimic bicipital tendonitis. In severe cases the pain may extend all the way down the arm to the hand, and up the back of the neck. If the clients is a side-sleeper, they won't be able to lay on the affected shoulder. Sleeping on the opposite shoulder may also produce pain if the upper arm isn't supported by a pillow.
The Subscapularis Trigger Points that Cause Shoulder Pain The Subscapularis muscle is one of the Rotator Cuff muscle. It lies deep in the armpit region and attaches to the inner surface of the shoulder blade. Like the other Rotator Cuff muscles, the Subscapularis contracts to rotate the arm, and to stabilize (hold together) the shoulder joint during movement of the arm. Trigger points in this muscle refer pain to the back of the shoulder, and also in a strap-like pattern around the wrist. These trigger points will also cause "frozen shoulder" syndrome, and will prevent a person from reaching their arm across to the other armpit.
Subscapularis Trigger Point Symptoms Clients presenting with active Subscapularis trigger points have often been diagnosed with frozen shoulder syndrome or adhesive capsulitis. They have pain deep in the back of the shoulder and limited movement of the shoulder joint.They typically cannot raise their arm to the side of their body past 45°, and will be unable to reach across their body. A hallmark sign of these trigger points, if present, is a strap-like band of pain around the wrist of the affected arm.
The Trapezius Trigger Point that Causes Shoulder Pain The Trapezius is the large, diamond shaped muscle group that forms the base of the neck and upper back region. It has attachment points at the base of the skull, along the spine, on the shoulder blade, and on the collar bone. When this muscle contracts it typically moves the shoulder blade, but it also plays a part in moving the neck and head. Trigger points in this muscle refer pain to the back and side of the neck, to the temple region, behind the ear or back of the head, and to the shoulder joint. Trigger points in this muscle develop for a number of reasons, including poor posture, emotional stress, whiplash injuries, falls, and sleeping positions (or sleeping under a ceiling fan). Trigger points in this muscle affect its ability to move the shoulder blade, and therefore will often contribute to common shoulder problems.
Trapezius Trigger Point Symptoms The Trapezius muscle can have up to four active trigger points in it, but for shoulder pain disorders the lower Trapezius trigger point is the most important. Nearly every client that I have ever seen has an active lower Trapezius trigger point. It refers pain, tenderness, and a "heavy" sensation to the top of the shoulder joint. This pain typically proceeds neck pain, shoulder pain, and headache symptoms. I typically begin all shoulder pain treatments by releasing the lower Trapezius trigger point, and any other active Trapezius trigger points.
Secondary Trigger Points in Shoulder Pain Complaints There are some trigger points in other muscle groups that can refer pain to the shoulder joint and cause shoulder joint dysfunction. The Deltoid trigger points are unique in that they refer pain only in the region that they are found. The trigger point in the anterior head refer pain to front of the shoulder, the lateral trigger points refer pain to the outside of the shoulder, and the posterior trigger point refers pain to the back of the shoulder. They may also produce a painful catch in the shoulder when raising the arm slightly to the front. The Supraspinatus trigger points refer pain to the outside of the shoulder and elbow. The pain is most often felt when trying to raise the arm to the side and a painful catch, like with the deltoid trigger points, may also occur during this movement. These trigger points may also produce shoulder snapping or clicking sounds.And finally, the Pectoralis major trigger points refer pain to the front of the shoulder, chest, and the inside of the elbow.