Like the hip, the shoulder is a ball-and-socket joint. Although the shoulder doesn’t support nearly as much weight or force as the hip, it’s still a complex structure of bone, muscle, and other soft tissue, all of which can contribute to shoulder pain, stiffness and weakness.
The collarbone (clavicle) and shoulder blade (scapula) form the socket that holds the round head of the upper arm bone (humerus). The labrum is the cartilage that forms the cup where the head of the humerus fits.
The rotator cuff, the muscles and tendons that surround the shoulder, holds the humerus in place and allows you to rotate your arm. Then there’s the bursae, the small sacs of fluid that cushion and protect the tendons of the rotator cuff.
In addition to the four muscles in the rotator cuff, there are 13 other muscles that enable movement in different areas in the shoulder. The deltoid, the largest and strongest shoulder muscle, gives you the strength to lift your arm.
You also have the AC (acromioclavicular) joint that connects the end of the scapula (acromion) with the clavicle. This joint must also be functioning properly for the shoulder to have full range of motion.
I think you get the picture.
There are a lot of connected, moving parts that can cause shoulder pain if they deteriorate or become injured. Shoulder pain can then make simple, everyday tasks, like washing your hair or getting dressed, difficult and uncomfortable. Here are some of the most common causes of shoulder pain.
Inflammation is the root cause of most painful conditions in the human body. Bursitis is inflammation of the bursae and rotator cuff tendonitis is inflammation of the tendons. Overuse of the shoulder can cause inflammation and swelling, leading to stiffness and limited movement.
For example, jobs that require repetitious overhead lifting can cause inflammation. Throwing a baseball is a very unnatural motion, which is why acute tendonitis is so common in baseball pitchers. These conditions can become chronic when caused by arthritis or long-term wear and tear.
Bursitis and tendonitis can also be caused by a shoulder impingement. When the top of the shoulder blade puts pressure on the soft tissue as you lift your arm, the shoulder blade can impinge or rub against the rotator cuff tendons and bursa.
Torn Rotator Cuff
A torn rotator cuff occurs when a tendon is partially torn or completely separates from the bone. Degenerative tears often begin by fraying, and damage tends to get worse over time with additional use. Lack of blood supply and bone spurs can contribute to a degenerative tear as well.
A torn rotator cuff can also be caused by an injury. For example, if you fall, attempt to lift something heavy with a sudden jerking motion, or dislocate your shoulder, you could tear your rotator cuff.
The various moving parts of the shoulder are contained in a capsule of connective tissue. When this capsule thickens, it causes tightness and stiffness around the shoulder. This severely limited movement is called frozen shoulder.
The degeneration of joint cartilage and underlying bone, the gradual breakdown that most people associate with the knees and hips, can also occur in your shoulders.
Additional causes of shoulder pain include:
Of course, shoulder pain could be caused by issues in other areas of the body, like your neck, back, and chest. That’s why it’s important to have your shoulder pain evaluated by someone who knows how to connect the dots between the symptom and the root cause. In the next post, we’ll discuss treatment options for shoulder pain.