Filed Under (Rotator Cuff Exercises, Scapular Stabilization, shoulder impingement, Shoulder Injury) by Rick Kaselj on 26-05-2010
What is Shoulder Impingement?
Shoulder impingement results from direct mechanical compression of the structures within the subacromial space, a limited space found between the head of the humerus and the acromion, the curved bony prominence from the top of the shoulder blade. The structures most commonly involved in shoulder impingement are the supraspinatus tendon of the rotator cuff, subacromial bursa and the long biceps tendon.
Without proper treatment and management, chronic compression of these structures can lead to a wide array of injuries, including degeneration and tearing of the rotator cuff, subacromial bursitis and biceps tendinitis. Alleviation of shoulder pain and treatment of shoulder impingement is possible through an appropriate exercise program.
By building stronger shoulders, the signs and symptoms, complications and disabilities caused by shoulder impingement will be eliminated. To understand how shoulder impingement is caused, it is vital to start with the basic anatomy of the shoulder joint complex.
What Makes Up the Shoulder?
The shoulder has the largest range of motion of any joint in the human body. It is especially designed to allow great degrees of mobility without difficulty and pain. However, because of its ability to move in a wide plane of motions, the shoulder is the least stable joint in the body, making it highly susceptible to injuries during overhead and rotational arm movements.
Each shoulder girdle is formed by a clavicle (collarbone) and a scapula (shoulder blade). The clavicle attaches to the breastbone to form the sternoclavicular joint, whereas the head of the humerus attaches to the scapula’s shallow socket called the glenoid fossa to form the glenohumeral joint, the major shoulder joint.
The rotator cuff muscles, consisting of the supraspinatus, infraspinatus, teres minor and subscapularis, fuse together and form a cuff or band surrounding the top of the humerus to hold it securely in place and to lift rotate the shoulder. Without an intact rotator cuff, the head of the humerus would move excessively off the center of the glenoid fossa, possibly resulting in impingement.
The subacromial space is frequently involved in shoulder impingement. Located below the acromion process and above the humeral head, the subacromial space contains the tendons of the rotator cuff, the long heads of the biceps and the subacromial bursa.
The bursae function as the gliding forces that reduce friction between tendons and bones. In a relaxed and neutral position, the size of the space is fairly wide; however, on arm elevation and inward rotation, the space narrows, consequently pinching on the structures within the subcromial space. To protect the structures from the squeezing effect, the subacromial bursa reduces the pressure.
If the impingement becomes too repetitive or too forceful, the involved structures are injured, leading to shoulder pain, weakness and reduced range of motion.
Rick Kaselj, MS
.
