The Supraspinatus Muscle: The Most Famous Of Your Rotator Cuff Muscles
Supraspinatus is one of four muscles that make up the rotator cuff and is probably the most well known of the rotator cuff muscles, with the others being: infraspinatus, teres minor and subscapularis. The major function of the rotator cuff muscles is to help keep the ball (head of the humerus) centrally located in the ball and socket joint of the shoulder. The rotator cuff muscles also help to lift the arm away from the body as well as rotate the arm which is where there name comes from and acre considered important shoulder stabilisers.
Pain and injury relating to the supraspinatus muscle is multifactorial and can be the result of trauma such as falls, a sudden lift, or due to repetitive loading. Tears in the tendon of supraspinatus and the other rotator cuff muscles are usually associated with increasing age and in my experience what we see in our Randwick and Sydney Physio practices are that tears are more common in the over 50’s population.
As per the image above, the shoulder can be considered to be made up of 3 bones, the scapula (more commonly known as the shoulder blade), humerus (the upper arm bone) and clavicle (again more commonly referred to as the collar bone). The “glenoid” of the shoulder blade and the “head” of upper arm bone form the “ball and socket joint” of the shoulder. Supraspinatus itself is a small muscle, the belly of which is located on the back of the shoulder sitting in the supraspinous fossa of the scapul,. from here the muscle travels under the acromium before inserting as a tendon into the superior aspect of the greater tubercle of the humerus (near the ball of the shoulder joint).
Supraspinatus Muscle Function
The supraspinatus and other rotator cuff muscles have a number of important functions, which is why if there is significant impairment surgical repair is often considered (depending on age and other individual circumstances). Some of the functions of the muscle are listed below:
- Contraction of supraspinatus initiates abduction of the arm at the shoulder joint and it is the main contributor for this movement during the first 15 degrees when first lifting your arm away from your side. It works in cooperation with the larger deltoid muscle to perform abduction. Beyond this early 15 degree range, the deltoid becomes increasingly more involved and effective at abducting the arm into positions of elevation once able to have a better line of mechanical pull.
- As one of the musculotendinous support structures of the rotator cuff, the supraspinatus helps to centralize the position of the ball in the socket. Resisting any inferior gravitational forces on the joint from the downward pull from the weight of the upper limb. helping prevent the head of the humerus slipping inferiorly in the socket. As well as this, along with the other rotator cuff muscles supraspinatus helps stabilize the shoulder by drawing the head of the humerus toward the glenoid fossa of the scapula (keeping the ball firmly located in the socket) when the shoulder is both at rest, moving and when under load during lifting, or weight bearing activities involving the upper limb.
- As a result, the supraspinatus and the rotator cuff as a whole is important in the prevention of shoulder sublaxations and is frequently the focus of rehabilitation programs when managing dislocation injuries, or reconstruction surgeries of the shoulder joint as well as painful conditions like bursitis and shoulder impingement.
Disclaimer: Sydney Physio Clinic does not endorse any treatments, procedures, products mentioned. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific advice or assistance regarding Supraspinatus: Muscle Of The Week should consult his or her orthopaedic surgeon, general practitioner, sports medicine specialist or physiotherapist.