“It’s definitely my Rotator Cuff…”

Around the baseball world we commonly hear players, coaches, parents and spectators make reference to the ‘rotator cuff’.  Has anyone stopped and asked themselves:

Do I really know what the ‘rotator cuff’ is and why it’s so important to the baseball player?

The cuff is, in fact, one of the most important group of muscles in the body for a baseball player to be able to perform game in and game out.  A baseball player is dependent on the ability to throw a ball and without that skill a player can no longer compete or will have great difficulty.

Before reading the article please reflect and consider how much you might know about “the cuff” and hopefully by the end you may have picked up a few more things to add to the repertoire.

The rotator cuff is a group muscles that cross the shoulder joint and run from the shoulder blade (scapula) to the upper arm (humerus).  This group consists of four muscles: Supraspinatus, Infraspinatus, Teres Minor, and Subscapularis.  Each of the muscles are found in the deepest layer of tissues and are covered by the main muscles of the shoulder cap (deltoids and trapezius).

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Figure 1: Muscles of the rotator cuff.  Anterior (from the front) view shows Subscapularis and Supraspinatus.
Posterior (from the back) view shows Teres Minor, Infraspinatus and Supraspinatus.

The muscles themselves have two major roles: (1) to elicit rotational movement of the arm bone (humerus) in its socket of the shoulder blade (glenoid fossa of scapula), and (2) to provide dynamic stability for the shoulder joint (glenohumeral joint).  The next question is…

“What is ‘dynamic stability’ and how does this group of muscles provide it?”

For joints to function properly there needs to be structures in place that keep them firm and in the right position.  This is what we, in the rehab field, consider to be stability.  Stability comes in two forms: (1) static, and (2) dynamic.    The term static infers no motion but from our perspective it means no active movement.  Things like ligaments and joint capsules are structures that keep joints together but we don’t have active control of them (they’re just there).  Conversely, the term dynamic means that the process is adaptable, changing or modifiable.  The reason why things are changing is because we have active (or conscious) control over these muscles and if we turn them on or off we can increase the stability of the joint.

The way the rotator cuff does this is simple.  When they are all activated the ‘rotator cuff’ muscle group will pull the round part of the arm bone (humeral head) into the socket of the shoulder blade (glenoid fossa of scapula).  In this stabilized position the baseball player can produce efficient, high velocity, skilled movements such as throwing a pitch at 90+MPH.  Anything that leads to this muscle group not working properly or becoming damaged has a profound impact on a baseball player’s ability to participate and perform at a high level.

Please feel free to leave questions or comments and we’ll try to clarify or provide some additional reference material.  In the next article, we’ll talk about different ways to train the rotator cuff efficiently and effectively.

Posted in Arm Safety
One comment on ““It’s definitely my Rotator Cuff…”
  1. Peter Francis says:

    Thanks! Great to hear!

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