What Exactly Is the Rotator Cuff?

The Anatomy

Ah, the infamous rotator cuff. Nearly everyone knows someone who has injured it, but what is a rotator cuff? During my physical therapy career, I have heard individuals call this a rotator cup, rotary cuff, rotor cup, and many other alternatives, but do not worry because we understand what you mean.

First, a rotator cuff is not just one object in your shoulder, but instead 4 different muscles. The name rotator cuff comes from these muscles forming a “cuff” around the ball-and-socket shaped glenohumeral joint. This ball-and-socket joint is problematic, because unlike your hip, the “ball” is substantially larger than the “socket”, which generates more instability. This is where the role of soft tissue comes into play to help assist in stabilization so frequent subluxations or dislocations do not occur.

The rotator cuff muscles (infraspinatus, supraspinatus, subscapularis, and teres minor) play a vital role in stabilizing your glenohumeral joint as well as other general shoulder movements. Since there are 4 muscles that make up the rotator cuff, this is the reason why individuals who injure this part of their shoulder may present so differently, depending on which muscle was damaged. Saying I “tore my rotator cuff” is an extremely general phrase, since it does not narrow down which muscle or muscles of the rotator cuff were specifically damaged. More often than not, the muscle injured is the supraspinatus due to its relatively small size but frequent loading of large forces.

As seen in the images above, the rotator cuff muscles originate from the scapula, also known as the shoulder blade, and insert onto the humerus where the muscles will pull on this bone for stabilization and movement. As they near the humerus, they become tendonous with the tendon portion of the muscle often being the part that is torn.

How Does One Injure It?

There are two types of injuries that can occur with the rotator cuff which we categorize as macrotrauma vs. microtrauma.

Macrotrauma injuries are when a large enough force at that instant supersedes the force which the rotator cuff can sustain. These types of injuries are often seen with falls, motor vehicle accidents, lifting too heavy of an object, etc.

Microtrauma injuries are due to the nature of repetitive overhead activities throughout a lifetime that eventually wears the rotator cuff muscles down enough to the point where they develop tears within the tissue. Individuals who are at a greater risk for microtrauma to the rotator cuff are overhead athletes (e.g. swimmers, baseball players) and those who are in manual labor professions (e.g. electricians, painters).

Unfortunately, once we age past 60 years old, we all become at higher risk for rotator cuff injuries due to the continuous use of our shoulders during our younger years. This is a large part of why the elderly population seems to have many more shoulder problems than younger generations.

As we age, blood supply to the rotator cuff starts to slowly diminish which decreases the integrity of the muscles, and may lead to weakening and fraying of these muscles. While this is microtrauma in nature, it also places the older individual at a higher risk for a macrotrauma event. That heavy suitcase you have been lifting your whole life without any issue may eventually reach the point where the weight is too much for the weathered rotator cuff, and as you go to lift it in the overhead bins, *SNAP*, and your rotator cuff is now torn.

The Treatment

People hear their rotator cuff is torn and often automatically assume the worst… surgery. But that is not necessarily the case for all individuals. While some may tear the muscle or muscles severe enough where surgery is needed, others may rehabilitate it completely back to normal with a combination of rest, physical therapy, and medication.

Full/Complete tears will not heal back together, thus surgery is needed for these injuries if one wishes to have full movement and strength back, but partial tears often depend on the extent of the tear. If the tear is small enough and has a good blood supply to it, then structured physical therapy which emphasizes the strengthening of the rotator cuff can return that individual back to pain free shoulder movement.

Regarding physical therapy for the rotator cuff, strengthening of the shoulder in all planes of motion is important to returning the muscles to their pre-injury strength. This is true for both injuries that do and do not require surgery. Also, since your rotator cuff muscles originate from the scapula, strengthening your periscapular muscles (muscles that surround the scapula and align it in the correct position on your back) is vital to long term rotator cuff strength.