Welcome to the ‘Physifitt does shoulders’ series!!
If you’re part of my mailing list (if you’re not what are you playing at!! Sign up here: Physifitt) you will know that my longstanding shoulder injury has raised its ugly head again and that a client of mine has become increasingly frustrated that his shoulder injury keeps flaring up.
It started by us having a conversation at his last session stemming from the question ‘Why are shoulders so crap?’
My aim is to start posing explanations in an attempt to answer this question over a series of blog posts throughout the rest of May. A new topic will be live each week so make sure you keep checking back in!
Part one will be focussed on shoulder anatomy.
Let’s start at the beginning. The picture above shows a very basic view of the shoulder complex. It’s made up of more than just your arm. It’s your arm (humerus), shoulder blade (scapula), collarbone (clavicle), breast bone (sternum), mid back (thoracic spine) and ribcage (inventively – ribcage) all working together to produce movement at the shoulder area itself.
Now these are all bones and if you’ve ever seen a skeleton you know that it doesn’t move by itself (if it does that’s quite spooky). It needs muscles, ligaments, tendons and nerves to get from one place to the next.
The nerves that supply the shoulder complex with its motor and sensory functions are located in the neck and upper back which leave their root and merge at the brachial plexus (sits just near your clavicle) to then innervate the arm. If there’s an issue with any of these areas, then this can cause problems to the shoulder that can sometimes be confused with being a local shoulder issue. More on things like this later!
Next up are the ligaments. Ligaments are strong fibrous structures which are passive (they don’t move actively) and are important for stability and preventing dislocations. The main shoulder ligament is called the glenohumeral ligament which is formed of 3 parts and this structure also forms the joint capsule which helps to keep the shoulder lubricated – think WD-40! The coraco-acromial ligament holds the coracoid (part of the scapula) to the acromion (pointy bit of the shoulder) and is commonly involved in impingement issues (more detail on this over the month). The coraco-clavicular ligament is actually 2 ligaments that attach the clavicle to the scapula. They are extremely strong but can be injured and will often be the cause of AC (the joint between your scapula and clavicle) joint issues. Finally, the transverse ligament holds the long head of biceps in its groove within the shoulder as it travels to the labrum.
The main muscles and tendons of the shoulders include the rotator cuff (supraspinatus, infraspinatus, teres minor and subscapularis), deltoid (anterior, middle and posterior), pectoralis minor and major, latissimus dorsi, trapezius (upper, middle, lower), subclavius, levator scapulae, teres major, rhomboid minor and major, serratus anterior, biceps (long and short head), triceps (long, lateral and medial head) and coracobrachialis. That’s a lot, and not all, of muscles within this region! All of these muscles have tendons at their origins and insertions which can also become injured. Muscles are active structures that can contract and relax. They also have a really good blood supply which makes their healing times a little less. Tendons however don’t have quite as good a supply and so can take a little longer to heal. The function of a tendon is to shift force from one region to the next in order to initiate movement.
This is all well and good but how does this movement actually occur? Especially smoothly? Surely all of these structures can’t possibly work together without something supporting them.
This is where structures like fascia (I’ve done a previous post on this so won’t be covering this here), bursae, labrums and even the skin layers come in to play.
Bursae are small fluid filled sacs that help to reduce friction between 2 surfaces. They are present throughout the entire body (easiest one to feel is at the front of your knee. The squashy bit just under your knee cap – poke it. That’s a bursa!) and help with fluid movement. In the shoulder specifically the main bursa structure is the subacromial bursa which sits between the rotator cuff and larger deltoid muscle. It’s a fairly large structure and is commonly involved in impingement issues (will talk more in later posts).
Briefly returning to the bones of the shoulder complex, the humerus and scapula meet one another at an area called the glenoid. The head of the humerus (which is round) sits within the glenoid cavity (which is quite small and shallow) and thus is known as a ball and socket joint meaning we have movement in all areas (forward, back, to the sides and in rotation). A round thing on a fairly flat surface tends to not be very ‘stable’ – a football on a table for example can go anywhere which isn’t too good when we’re looking for things to stay together. This is where labrums are important. A labrum is a piece of cartilage which is fibrous in nature. In the shoulder, this structure sits within the glenoid cavity and encircles the head of the humerus which allows for the joint to become a little deeper and thus a little more stable. The tendon of the long head of the bicep actually attaches within the labrum as well providing it with another layer of support. Think of the labrum as a washer for a screw – it seals the two sides of the joint together.
Don’t forget – your skin is a piece of connective tissue as well and we need good mobility of the skin to assist with human movement. If you have a scar for example your skin and therefore movement in general will be restricted within this region.
So, there you have it! A brief overview of the anatomy of the shoulder. There’s a heck of a lot of stuff in there which all has the possibility to be injured. Next week we will be looking at what the common issues are and the final part of the trilogy will be treatment methods and the evidence behind them.
There’s a lot of information in here. If you need any further info or have any questions drop me a line =]
*please note that this series is for information purposes only. Should you be experiencing issues with your shoulder, or any joint in general, please contact a relevant healthcare provider for accurate assessment, diagnosis and treatment