The pain of shoulder injuries (Part 3)

Okay, so this is 'the article that had to be'. Like many professionals I can assume that people have more knowledge than they may indeed have. It is time to rectify that assumption and give you the deepest facts about the rotator cuff muscles. I hope by the end of this that you will not only know their individual names and functions, but then look over the previous two articles and really gain more insight into the total picture. The following notes are essentially part of the information I give patients who come to me for treatment regarding shoulder injuries.

 

Let us now name the rotator cuff.

Next let us learn about each individual muscle. Remember: All of these muscles begin/originate at your scapula and end/insert upon your humerus. Thus their role, working together, is to stabilise your humerus when it moves.

 

 

Subscapularis
This is a large triangular muscle that fills the subscapula fossa (area on the interior surface of the scapula). It converges as it attaches laterally onto the lesser tubercle of the humerus. The action of this muscle is Internal Rotation.

 

Supraspinatus
This muscle originates above (supra) the spine of the scapula - this is its origin. It converges under the acromium to become a tendon that attaches onto the highest facet of the greater tuberosity on the humerus. Action - Abduction.

 

Infraspinatus
Like the name says, this muscle begins or originates below (infra) the spine of the scapula and occupies most of the infraspinatus fossa on the scapula. The muscle converges laterally to insert on the anterior surface of the humeral head or more specifically the middle facet of the greater tuberosity. The action of the infraspinatus is lateral/external rotation.

 

Rotor Cuff Action
The function of the rotator cuff is to act with co-ordination upon the humeral head to maintain optimum position with its relation to the glenoid cavity. When raising the arm laterally, the supraspinatus initiates the movement prior to the deltoid taking over. During the initial abduction subscapularis, infraspinatus and teres minor counteract the upward pull of the deltoid and when aided by the supraspinatus they produce a force perpendicular to the shaft of the humerus that enables smooth, pain free movement.

 

Now, if you look at the accompanying diagrams, you should be able to piece this jigsaw together quite well. This is the whole point of the article: that shoulder injuries begin with anatomy. Now, as a professional, I use my knowledge of this relationship to establish what is not working correctly. As in part 2 of this series on shoulder injuries, I use specific test movements to determine what is weak, strong, loose, tight, painful etc. Then I apply specific exercises to address those problems. This is why a quick shot of ultra-sound does not fix a chronic shoulder.

 

Yes, so one day soon I will get to write that article that shows you specific exercises to fix certain shoulder problems. Maybe this will be part four...

MUSCLE                                 SHOULDER ACTION
 
Subscapularis – Rotator Cuff              Internal Rotation
Supraspinatus – Rotator Cuff             Abduction