Anatomy 101: What is the Rotator Cuff?

May 3, 2022 | Healthy Body

We hear from our clients about a lot of rotator cuff injuries.  We also hear a lot of misinformation when it comes to the rotator cuff:  what it is NOT called (rotary cup, rotate cups, rotisserie cuff) as well as how it is treated (my rotator cup was removed).

Your rotator cuff is actually a group of four muscles and tendons (tendons attach muscle to bone) that keep the ball (head) of your upper-arm bone (humerus) in your shoulder socket. It also helps you raise and rotate your arm.

Each one of these muscles is part of the rotator cuff and plays an important role:

  • Supraspinatus. This holds your humerus in place and keeps your upper arm stable. And helps lift your arm. This is the rotator cuff muscle that is most frequently injured.
  • Infraspinatus. This is the main muscle that lets you rotate and extend your shoulder.
  • Teres Minor. This is the smallest rotator cuff muscle. Its main job is to assist with rotation of the arm away from the body.
  • Subscapularis. This holds your upper arm bone to your shoulder blade and helps you rotate your arm, hold it straight out and lower it.

Rotator cuff injuries are very common and can include tendinitis (inflammation of the tendon), partial tears and complete tears.  Many injuries are due to overuse and repetitive motions (think baseball pitchers, painters, window washers).