The shoulder is a complex and fascinating joint that, when healthy, operates with the trunk and hips to effectively produce and resist force. It can allow you to hold graceful handstands, to lift humans over your head and even to give yourself a good old pat on the back. Along with such vast potential of movement, however, there is also a potential for injury.
While it is possible for a shoulder problem to stem from the shoulder itself, it is equally likely that the issue is more multi-factorial. Enter a crash course in shoulder anatomy:
The Bones: The shoulder is a ‘ball and socket’ joint where the head of the humerus (or upper arm bone - the ball) sits inside the glenoid fossa of the scapula ( the socket - on the shoulder blade. The shoulder blade also interacts with the clavicle (or collar bone) which then interacts with the manubrium of the sternum (or breast bone).
Now the humerus and the scapula are good friends. They dance together in a rhythm known as the scapulohumeral rhythm when lifting the arm overhead. For every 2 degrees of glenohumeral (ball and socket movement) there is 1 degree of scapulothoracic rotation (the movement of the shoulder blade on the ribs. Why is this important? If the scapula wanted all the limelight and didn’t move, the humerus would run out of room to lift up and hit a bony landmark on the scapula known as the acromion, pinching soft tissue structures in between. On the other hand if the scapula can rotate upward, so can the socket that the humerus sits in, making overhead movement possible (up to 170 degrees). “But what about the other 10 degrees?” Read on my friends.
The Muscles: Contradicting the subtitle, we must think of movements before individual muscles. Our body is always working together as a unit. Thus, it is better to divide the muscles into 3 classifications
i) Protectors
ii) Pivoters and
iii) Positioners.
I) For the gleno-humeral protectors we have the Rotator Cuff, the Deltoid, and the Biceps.Their goal? To fit the ball inside the socket and depress the humeral head. The force of the protector muscles actually oppose each other, which is what creates the stability. Thus, balance of those muscles is important.
II) For the scapular pivoters we have the trapezius, the levator scapula, the rhomboids, the pectoralis minor and the serratus anterior. As aforementioned, the ability for the humerus (or upper arm bone) to move in the socket is dependent on the position of the socket. These muscles help to move the scapula around ( the bone that has the socket), such that movement in a variety of planes is possible. The scapulothoracic joint is barely a joint. It is really the shoulder blade just floating on the rib cage. As a result, control and balance of all these pivoters is paramount.
III) Last of the 3, we have the humeral positioners - the deltoids, the pectoralis major, the triceps brachii and the latissimus dorsi. This team helps to move the humerus toward and away from the body in a variety of planes.
“You are as old as your spine”: The next key player of your shoulder health is actually your spine. The nerves running from cervical spine (or neck) from about C5-T1, pretty much control your entire shoulder and arm. As a result, when you come in for a shoulder issue more often than not we will be addressing the neck too. The thoracic spine ( mid back) has a large influence on the efficacy scapular pivoters and humeral positioners.
As promised, the remaining 10 degrees is actually achieved through the extension and side flexion of the cervicothoracic region of the spine (neck and upper back), further driving home why posture and the neck are so key to shoulder function. Lastly, even your lumbar spine and hips can be involved in shoulder health due to your latissimus dorsi‘s connection to the thoracolumbar fascia. As a result even lumbar posture and core stability can be an important part in core stability.
And at the end of the day everything begins with the breath. Breathing is always the first step. Do that right and you will always be setting yourself up for success.
If you would like to dive more into the depths of improving your shoulder be sure to book in for my Shoulder Therapy Osteopathy 4-Pack or contact us for our Monthly Bazooka Rehab program to learn about how your brain is involved with shoulder pain.
