Shoulder Part 1: What makes up our shoulder joint and how does it work?

The Shoulder Joint Part 1


Your shoulders do a lot of important things to might take for granted.  They help you get something off of a high shelf, comb your hair, lift your children or play a game of tennis or catch.  It’s a complicated process that your shoulder makes look easy.

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The shoulder is the most flexible joint in the entire body.  The shoulder joint is formed by the humerus (arm bone), the scapula (shoulder blade) and the clavicle (collarbone).

The shoulder is a ball-and-socket joint formed between the articulation of the rounded head of the humerus and the cup-like depression of the scapula, called the glenoid fossa.  The glenoid fossa forms a very shallow socket, so the muscles ligaments and cartilage of the shoulder joint reinforce its structure.

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One of the major supports to the shoulder is the rotator cuff muscles.  Your rotator cuff is made up of muscles and tendons that keep the ball (head) of your humerus (upper arm bone) in your shoulder socket.  It also helps to raise and rotate your arm.

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Each one of these muscles is part of the rotator cuff and plays an important role:

Supraspinatus: This holds your humerus in place and keeps your upper arm stable.  It also helps life your arm.

Infraspinatus: The is the main muscle that lets you rotate and extend your shoulder (like reaching into the back seat of your car).

Teres Minor: This is the smallest rotator cuff muscle.  It’s main job is to assist with rotation of the arm away from the body.

Subscapularis:  This holds your upper arm bone to your shoulder blade and helps you rotate your arm towards you

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Common Injuries:

A Rotator Cuff Tear: is often the result of wear and tear from daily use - AND IS COMPLETELY NORMAL!  You’re more likely to have this if you have a job where you need to move your arm a certain way over and over, like a painter or carpenter, or if you play sports like tennis or baseball.  It can also happen if you fall on your arm or try to lift something heavy.

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Tendinitis: is inflammation or irritation of a tendon that attaches to a bone.  It causes pain in the area just outside the joint.  Tendinitis can often be the first occurrence before a tear.

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Bursitis: is when the bursa (a small sac filled with fluid that protects your rotator cuff) gets irritated.  That can happen when you repeat the same motion over and over again.

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So should you avoid all activities, hobbies and sports that involve movement above your head?? Of course not!!  You simply need to move smarter.  Making sure all your postural muscles and rotator cuff muscles are strong will ensure your movement is occurring in a way that does not compress the shoulder joint and subsequently the rotator cuff tendons, which causes the injuries listed above.

Is it too late?!? 

If you are already experiencing pain in the shoulder, or have had a form of diagnostic imaging (Ultrasound or MRI) done and it has told you that you have tendinitis or a rotator cuff tear, there is still a lot you can do!


Stay tuned tomorrow for "The Shoulder Part 2: Do I need surgery?" to review if you are a surgical candidate or not and exercises you can do to help with pain and limitation.