The resting position of the shoulder-blade is important to the health and comfort of the muscles of the neck shoulder and upper back, and also to the nerves that run from the neck into the arm.
I recently taught a shoulder course, and so neck, upper back pain and nerve pain into the arm have been on my mind a lot. These are very common problems that many people suffer from, and although they can have many different causes, improving overall posture as well as the resting position of the shoulder-blade are frequently overlooked as potential solutions.
The shoulder blade or scapula is the triangular bone that sits on the back of our upper ribcage, which houses the arm socket. But unlike the hip socket which really is a cup that the leg bone (femur) sits in, the arm socket is shaped more like a tiny plate. Furthermore, the ball that forms the top of the arm bone (humerus) is a lot larger than the plate of the socket, so it is a bit analguous to a golf ball on a tee rather than in a cereal bowl. Except of course, when we talk about the shoulder joint, the plate is sitting on its rim. It becomes immediately obvious that the joint itself is inherently unstable, and it must largely rely on the ligaments, tendons and muscles that surround it to “strap” the arm to the body.
However, the angle of the plate can make a big difference to the strain the muscles are placed under. If the plate of the socket is angled up a slight bit, the humeral head (arm ball) can rest on the rim, whereas if the plate of the socket is angled down, the humeral head is essentially falling out of the socket, and the muscles have to work much harder to hold the arm in place.
Also, if the glenohumeral joint is pointing down as can be seen in the upper left diagram, usually the shoulder-blade will not rotate far enough when the arm is moved up overhead, and the arm bone (humerus) will bang up against the bony protuberance of the shoulder-blade called the acromion, creating an impingement problem, which may in time damage the supraspinatus (rotator cuff) tendon.
Furthermore, if the glenohumeral joint (arm socket) is angled down, the nerves that leave the cervical spine to go into the arm have a very long way to go - much further than if the glenohumeral joint were angled up. Nerves don’t like being stretched, and stretched nerves tend to be painful. I find that when I see someone that has a shoulder socket pointing down with radiating arm pain or sore neck/shoulder muscles , I tell them to relax, and I pick up their armpit (actually the upper arm near the armpit) and hold it up for a few minutes. Frequently their pain goes away, and then I know that providing an exercise program that improves the position of the shoulder socket will probably work.
So, how do you tell if your arm socket is pointing up or down? Tough to do on your own, but if you have very long, sloped shoulders you can be suspicious. If the outer end of your collarbone is lower than its attachment at the sternum, your glenohumeral joint is pointing down. Most of you will need to ask a friend or partner to look at your shoulder blades from the back. If the bottom corner of the shoulder blade is closer to the spine than the top part of that inner border as shown in the left upper diagram, then your shoulder joint is pointing down.
If you are in pain and you discover that your socket is pointing down, you need to find a good physiotherapist , CHEK Practitioner or an extremely knowledgeable personal trainer that can teach you how to build muscle endurance in serratus anterior, low traps, and upper traps without overusing levator scapula, rhomboids, and lats, and even more importantly, teach you how to move your arm and shoulder-blade so that you recruit the right muscles in the right order to keep your shoulder, upper back and neck happy.
Sahrmann, Shirley Diagnosis and Treatment of Movement Impairment Syndromes Mosby Inc., St. Louis, Missouri, 2002.
Kendall and Kendall Muscles: Testing and Function, with Posture and Pain (Kendall, Muscles) Williams and Wilkins, Baltimore Maryland, 2005.
Donatelli, Robert A. Physical Therapy of the Shoulder (Clinics in Physical Therapy) Churchill Livingstone, St. Louis, Missouri, 2004.
Porterfield, James and DeRosa, Carl Mechanical Shoulder Disorders: Perspectives in Functional Anatomy with DVD Saunders, 2003.
Cailliet, Rene Shoulder Pain (Pain Series) 1991.
Chek, Paul C.H.E.K. Practitioner Level 3 Certification Manual - The Upper Quarter The Chek Institute, 2000
Copyright 2008 Vreni Gurd