One of the reasons that patients find medical terminology very confusing is because medical terminology is very confusing.  Confusing even for doctors.  However, we are used to the bizarre terminology, so it doesn’t seem quite as strange to us.  Of the many strange rituals that are learned in medical school, one of them is the acceptance of mysterious names.  A good example of this is the term, “rotator cuff.”  Most of my patients get this term only partially correct.  The more common variations are:  “rotatory cuff;” “rotator cup;” “rotator cuff;” and just plain “rotater,” not to mention it’s younger sibling “roter.”

The fundamental problem is that the anatomy being referenced doesn’t fit the terminology that has become common parlance.  “Rotator cuff” sounds like the description of something that rotates, like a helicopter blade.   And “cuff” reminds me of the part of a shirt that holds a cufflink: the end, or surrounding edge of a piece of fabric.  Of course, the image of someone being whacked on their head by the back of someone else’s hand, in essence being “cuffed,” also seems intuitive.

In reality, the rotator cuff is a term used to describe four muscles in the shoulder area.  The muscles are, in no particular order, the supraspinatus, the infraspinatus, the teres minor, and the subscapularis.  They all blend (to some degree) together and attach at various adjacent points around the top of the humerus bone (the “ball” of the shoulder’s ball-and-socket joint).  So when you raise your arm in front of you, or place your hand on your stomach and then move it away as if you were going to shake hands (or vice versa), the rotator cuff is partially responsible.   I suppose this effect on rotation of the humerus partially justifies the “rotator” part of the name; the blending together of these four muscles may be why the word “cuff” got into the mix.  Personally, I think a term like “humeral hood” makes sense.   Actually, “the gang of four” would be more intuitive, but I don’t make up the rules.

A rotator cuff tear usually means that some portion of these four muscles has a hole in it.  The tear can be partial, which is similar to a piece of carpeting that is worn down, but doesn’t yet have a complete defect through which the floor boards can be seen.  A “complete” rotator cuff tear usually means that there is a physical, full thickness defect in the rotator cuff.  To make matters more confusing, the term “rotator cuff tear” doesn’t really tell you which muscle is torn.  Typically, it is the supraspinatus that is torn or damaged, which is the rotator cuff muscle that is located on top of the humeral head and is the one that is most commonly associated with pain and weakness when it is damaged.  But a tear of the subscapularis or teres major muscle (less common) could also be technically described as a rotator cuff tear.

The rotator cuff, aside from having a peculiar name, also demonstrates some peculiar behavior.  Some tears occur slowly over time and are merely a sign of the normal process of aging.  Some tears can occur suddenly as a result of trauma or overuse of the shoulder, and it is these tears that tend to be most symptomatic and often in need of treatment.  Sorting out whether a tear is brand new or has been there for awhile can be tricky even with careful study of MRI images.

In any event, the next time you hear the term “rotator cuff,” you’ll know that it refers to a group of four muscles surrounding the top of the shoulder.   I know what rotator cuff pain feels like; I hurt my shoulder by doing too much overhead work in my basement workshop last summer.  Fortunately all it took was two weeks of rest and some anti-inflammatory medication and my Gang of Four felt fine.

The Illinois Bone and Joint Institute/ University of Chicago Pritzker School of Medicine

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