The Shoulder Explained

anatomy,bones,clavicles,collarbones,healthcare,shoulders,x-rays,ball and socket joints,humerus,orthopedics

The shoulder complex is by far one of the most fascinating structures in the body because it has an amazing range of motion, but this all comes at the expense of stability.   Many of us have probably experienced some degree of shoulder pain during exercise, and wrote it off as simply being exercise-related.  However, that same shoulder may have started to become achy, lasting hours even after the exercise, or the range of motion of the arm became limited.  It’s usually at this point where patients present clinically,  wondering “which muscle they can stretch out or strengthen” to avoid this discomfort.  The answer, once again is not simple, due to the complexity of the shoulder complex.     This article will look at the basic structure of the shoulder complex and how the athlete may be able to prevent shoulder injuries, including training considerations.

Shoulder Anatomy

When considering the shoulder joint, it is commonly thought of as simply that ball-and socket joint where the arm attaches to the upper body.  Technically, however the shoulder complex consists of 4 separate joints: 1) The gleno-humeral (GH) joint (aka “the shoulder joint”) is a ball-and-socket which joins the upper arm bone to the shoulder blade, 2) the sterno-clavicular (SC) joint located between the top of the breast bone/sternum and the collar bone/clavicle, 3) the acromio-clavicular joint, joining the shoulder blade to the collar bone, 4) the scapulo-thoracic joint which is a “virtual” joint between the underside of the shoulder blade and the thoracic spine and ribcage.  It is also one of the most mobile joints which permits the arm to go through a wide range of motion.

Stability & Flexibility

Stability of this complex is provided by the prime movers of the arm:  the pecs, lats and delts, assisted by four small strap-like muscles cumulatively known as the rotator cuff: supraspinatus, infraspinatus, teres minor and subscapularis.  These four muscles work in synchronicity to stabilize the shoulder blade and ensure depression of the shoulder’s ball-and-socket joint (GH joint) in order to counter the upward pull of the deltoid muscle.  If there happens to be an imbalance amongst these small 4 strap-like muscles, a squeezing of the rotator cuff where they attach at the arm bone (humeral head) and part of the scapula (coraco-acromial arch) may result in primary “impingement”.  Any activity that involves bringing the arms overhead such as bringing weights overhead (shoulder presses), swimming, throwing or racquet sports, has the potential to the compromise rotator cuff if functional stability measures are not in place.

Conditioning all the muscles of the shoulder complex through targeted strengthening and stretching exercises will help to ensure balanced development of both the primary movers (pecs, lats and delts) and the muscles of the rotator cuff.   It should also be noted that differences in the structural anatomy of the scapular acromion may also predispose an individual to impingement, so it is equally important to rule out structural causes through an x-ray.

Core stability is also another often over-looked component to ensuring an efficient shoulder complex.  In the September Issuer of Growing Y-ser, I went over the importance of developing core strength as an anchor to increase the power and stability. As mentioned prior, the core complex can be visualized as a cylinder – the diaphragm (a major respiratory muscle) as the lid, and the muscles of the pelvis at its base. This cylinder houses the bony structures of the spine, hips, pelvis, abdominal structures, and upper legs.  Since the core is located centrally in the body, a strong core provides the power source and stability for arm movement.

Training Tips to Keep Your Shoulder Healthy

Avoid lifting beyond your capacity.  Gradually increase training workload; avoid exceeding a weight increase of 10% per week.  Allow 3-4 weeks for accommodation.  Limit the increase of weight to one exercise per workout.

Be aware of exercise technique.  Incorrect form during training may place excessive stress through supporting structures, predisposing them to injury.

Avoid lat pulls behind neck, and upright rows

During one-arm rows, watch that the weight doesn’t allow the shoulder to traction at the beginning of this exercise

Focus on maintaining a balance in flexibility.  The goal for stretching  the internal and external rotators of the shoulder should be to achieve a balance between the two groups , relying less on the degree of flexibility;  excessive flexibility at the expense of muscle strength and control strains the more passive stabilizers of the shoulder including the capsule and ligaments which may predispose the shoulder to labral tears, or even dislocation

Prior to commencing any training program, seek the advice of a qualified health professional  if your shoulder has a history of instability where the shoulder has popped out of joint, if you notice joints in your body that are very loose or if you hear excessive popping sounds in the shoulder.