ERGONOMICS Tutorials: Have a Joint: #1: The shoulder

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 ERGONOMICS Tutorials: Have a Joint: #1: The shoulder

by Kathleen Hogan, physical therapist

Welcome to the new blog dedicated to teaching you about your body. Part fact, part my experience. Thank you to Wikipedia for the illustrations.


Pectoral girdle front diagram.svgShoulderjoint.PNG

The shoulder: Three bones come together, your humerus (upper arm bone), your scapula (affectionately known as your ‘wing’ or your ‘blade’), and your clavicle (‘collar bone’). These three bones are held together by ligaments (bone to bone gristle with very little blood supply), tendons (the ends of muscles that attach to bones), and muscles.  The scapula has a little hook that comes forward and attaches to the end of the clavicle. The clavicle attaches to the breastbone. The top of the humerus fits into a space in the scapula, a ball and socket type joint.

The shoulder joint is highly mobile due to this lack of a tightly packed joint like the hip. From Wilipedia: “The shallowness of the fossa and relatively loose connections between the shoulder and the rest of the body allows the arm to have tremendous mobility, at the expense of being much easier to dislocate than most other joints in the body.” Actually a group of five joints, the shoulder allows movement into 6 directions: flexion (reach up), extension (reach behind you), abduction (reach straight out to the side), adduction (bring your arm to your side), internal and external rotation (twist the arm in and out). The scapula moves against your rib cage into elevation (up), depression (down), retraction and protraction (swinging in and out).

The muscles that hold onto the top of your humerus are called your rotator cuff. They stabelize the upper arm while it moves in all those different directions. There are lots of other muscles too, and of course nerves, arteries, veins, a lymphatic system and bursa (fluid filled sacs between surfaces of bone and muscle or tendon). So now you have an armpit, and a shoulder capsule or socket. One of the cuff muscles, the supraspinatus, goes right under the big bursa (fluid filled sac) that covers the top of your humerus and is under the hook part of your scapula. It can get squished rather easily if you have weakness and fall, or lift too much (see below).


You can tear your rotator cuff, then you have a “torn rotator cuff”; that’s the official name. You can tear your cuff in many ways such as: lifting too much weight, especially if your shoulder muscles have gotten a little weak from being on the computer all the time with your shoulders hunched. The only muscle this strengthens is your upper trapezius, your “Oh please, someone rub my shoulders” muscle.) When you lift something heavy, your deltoids (muscle that covers the top of your upper arm) LIFT the top end of your humerus (not laughing now) which pinches your supraspinatus between the top of your humerus and the hook of bone coming off your scapula and over the top of your shoulder (you can feel this bony hook easily).

NOTE: The cuff muscles are supposed to pull the top of your humerus DOWN when you lift your arm. Yes, that’s right, the top of the upper arm bone goes DOWN into the ball and socket joint when the elbow and hand go up.

Another fun way to tear your rotator cuff is to fall on your arm. If you are kind of old, or middle aged, or even young but you’ve been lifting babies and sacks of groceries, or logs, or 2 x 4’s or what ever for along time and you’ve put alot of stress on your shoulder just by using it , the ends of the muscles attaching to the humerus and scapula-hookie thing may be thinner than they should be and when you catch yourself on your hand, rip, off they go, tearing away from the bone. Sometimes this heals with time, rest and exercise, sometimes you need surgery to repair it.

Then there is “frozen shoulder” a strange syndrome that can just appear for no reason. Your shoulder starts to hurt all over the place, especially at night. This syndrome is most prevalent in people of middle age, women more than men. It does go away by itself, in a few months to three years. But first it travels through stages, getting worse and worse until you can’t lift your arm past the horizon. Because… your cuff muscles can no longer LOWER the head of your humerus into the socket. The socket is thickened, the little fluid filled sacs in there have become sort of dried out, the tendons are inflamed.

SO… I know you want to do more than wait!


Here’s the good news. You can (help) prevent frozen shoulders (some of them are a complete mystery, we’re not talking about those here) and rotator cuff tears by doing the following:

1. When you are sitting in front of your computer, as you are right now, lower your shoulder girdle (all three of those bones mentioned above). Now raise it up so your shoulders are near your ears. Now bring it down and now back, pull your blades together in the back. Get your hands off the keyboard!!! Back! Now hold it. Now put your hands on the keyboard again but keep track of where your shoulders are (down). Make some nice big circles with your shoulders.

2. The only way you can do #1 is to sit up straight. Put your feet under the chair, arch your low back a bit, drop your shoulders. Your chin should be neither up nor down. Your monitor should be slightly below your eye level. Good!

3. When you raise your arms overhead make sure your thumbs are pointed up, never raise overhead with your thumbs pointed down. Stop it! I said never! With your thumbs down, you betcha you are going to eventually pinch one of your shoulder muscles between the end of your humerus and your scapular hook.

4. NEVER do chair push-ups in the seated position, as in sitting between two chairs and pushing on them to raise yourself.

5. ONLY do push-ups from the kitchen counter, the bathroom counter, the kitchen table, the wall…you get the picture, not the floor unless you know there is nothing at all wrong or hinkie with your shoulders. Stop all macho posturing unless you are in good shape. OK you can do girl push-ups from the floor but only if you are hink-free in the shoulder department. If you are a person in great shape, do anything you want. Except don’t do those pull-down things with your arms coming down behind your back pulling on a pulley with weights. Your thumbs are down! bad! bad! You can tear your biceps tendon that runs into your shoulder. Stop it!

6. When you are sitting at your computer, lower your shoulder girdle and lift your arms overhead with your thumbs up. Every day several times a day, especially if you have other disabilities, like diabetes. For some reason people with diabetes get frozen shoulders more easily than others. FEEL the head of your humerus lower into the socket. Hold onto it with your cuff muscles. STABELIZE the heads of your humeruses. (humeri?) GOOD!

7. Still sitting there? Try this one: Put your arms out to the sides, thumbs up. Bend your elbows to 90 degrees. Slowly swing your hands in an arc from pointing at the sky to pointing at the ground, keeping your elbows out. SLOWLY!!! Keep your shoulders back. Now hands up and bring your elbows in to touch each other in front of your chest, now squeeze your shoulder blades together in the back, forward, back.

8. Put your hands under your rump, palms up. Pull your shoulder blades together and down. Stretch your chest muscles (your pectoralis major and minor, the front muscles of your armpits). Your pecs can get very tight from being at the computer, especially if you are all hunched up with your back rounded and your chin jutting out. Sit up straight!

9. When you are carrying groceries or anything else, use your biceps (bends your elbow and attaches up there in your shoulder) and tense all your muscles, lift that bag! Don’t just let it pull your arm out of the socket! Use the muscles in your entire arm. Lift and lower the bag as you walk across the parking lot! USE YOUR MUSCLES. This will protect the shoulder from pulling apart and straining your biceps tendon, and your cuff muscles. Your poor upper trapezius will appreciate some other muscles doing the work for a change.

10. OK so your shoulder hurts. Don’t lift much of anything and if you have to, hold it close, use both arms, tense all your muscles.

11.Ice your shoulder for 15 minutes, then use some heat twice a day.

12. See if you can figure out which movements caused this pain. Stop doing them if you can. Stop all push-ups of any kind.

13. Get a massage. Massage is the only modality besides ultrasound that gets circulation going deep down in the muscles. You need to move out the inflammatory by-products and bring in fresh blood cells to help with that process and to bring oxygen to the tissues.

14. Don’t make sudden jerky movements. Be careful how you move your arm. Especially keep your arm in the thumbs-up position when you move.

15. Lay your arm on a LAP DESK or pillow/jam a pillow up under your armpit when sitting on the couch. Support it at night. At the computer, see if you can give the arm more support on a lower shelf/keyboard support. Use a lap top instead of a desktop and a LAP DESK just to see if changing your entire bodily support will help.

16. Ask your doctor about a TENS unit (electrical stimulation), and pain meds. Use anti-inflammatories if you can.

17. Use your good arm to help raise the painful one overhead; don’t stop reaching overhead but you may need to lay down first so you are not lifting against gravity.

18. Visit a doctor and obtain a referral to physical therapy if changing your movement patterns does not take away the pain. You will most likely need someone to mobilize the head of your humerus if your pain becomes chronic. These movements are impossible to do yourself. The P.T. can mobilize if the capsule isn’t entirely thickened. S/he will evaluate which stage of a frozen shoulder you are in and whether or not you have a rotator cuff tear. S/he will move your arm for you and carefully stretch the muscles and joint capsule. The P.T. can show you the exact exercises you need for each stage of recovery. The more complex exercises are not covered in this blog. S/he can refer you to an orthopedist if the case is too serious for P.T.

19. See an orthopedist for x-rays and even an MRI. The MD may mobilize your shoulder under anesthesia and send you back to P.T.

20. Some people swear by drinking pure aloe vera for frozen shoulders. Be sure to research both conditions and take care of yourself!

One Response

  1. Thank you! I have been having problems with my shoulder and I will certainly use your tips!

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