Learn Muscle Anatomy: Of Dads and Rotator Cuff Injuries

If my dad tells me about the hockey game that led to him tearing his rotator cuff one more time, I’m going to tear the rest of his arm off and beat him with it. I’d rather he’d relive his glory days a little less and focus more on being seen by a doctor for his rotator cuff issues. But because he never got adequate help with his rotator cuff tear when he was younger, I’m doomed to a lifetime of watching His Stubborness wince every time he scratches the back of his head.

Dads. Am I right?

What is the rotator cuff, though, and why does an injury to it have such an impact? Read on! If you’re my dad, read on and then please go see your doctor.

sports-injuries-shoulder-rotator-cuff-musclesImage from Human Anatomy Atlas.

The rotator cuff is a group of muscles and tendons that surround the shoulder joint. These muscles keep the top of the upper arm in the shoulder socket by forming a "cuff" that not only holds the arm in place but helps it move in various directions.

The rotator cuff muscles hold the ball at the top of the humerus firmly in the glenoid fossa. The rotator cuff muscles are the supraspinatus, subscapularis, infraspinatus, and teres minor.






Subscapular fossa

Lesser tubercle of the humerus

Medial rotation of the head of the humerus; prevents anterior displacement of the humerus


All of the supraspinatus fossa

Greater tubercle of the humerus

Assists the deltoid in abducting the arm; stabilizes the glenohumeral joint


Infraspinatus fossa on the posterior surface of the scapula

Greater tubercle of the humerus

Laterally rotates the upper limb; stabilizes the glenohumeral joint

Teres minor

Lateral border of the scapula

Greater tuberosity of the humerus

Lateral (external) rotation of the humerus; helps protect and stabilize the shoulder joint

Rotator Cuff Injury

When my dad was in high school, he played on our hometown hockey team and ended up… in a fight? In a dogpile? A ninja battle? I don’t know, I feel like the story’s changed over the years. Regardless, he tore his rotator cuff while tending goal and, thanks to our family’s particular strain of stubbornness, never got it properly checked out. It’s been plaguing him ever since.

Image from Muscle Premium.

Tears are typically categorized in two ways: if they have partial thickness or full thickness, and if the tears are traumatic or degenerative. Gradual degeneration, like repetitive overheard motion of the shoulder (think of baseball pitchers), or sudden traumatic events (my dad at hockey) can tear one of the muscle tendons of the rotator cuff. It’s usually a torn supraspinatus that ends up causing the bulk of the issues.

Rotator cuff tears usually occur at the insertion point on the head of the humerus so that the tendon will no longer fully attach to the bone. Want to see it in all its gruesome action? You’re in luck! We’ve got a super short animation about it:

Symptoms of a rotator cuff injury include pain, decreased range of motion in the shoulder, and muscle weakness.

Treating a rotator cuff injury can range from easy (physical therapy being the most common) to invasive (surgery). I’ve been hounding my dad to have surgery on his shoulder for years, but he hasn’t budged yet. I’m not sure what he’s waiting for.

There are several types of surgery to treat the rotator cuff, including open tendon repair – in which a surgeon reattaches the tendon to the bone – and shoulder replacement – in which a surgeon installs the ball part of the artificial joint onto the shoulder blade and the socket part onto the arm bone (but this is reserved for only the most massive rotator cuff injuries coughdadcough).

Minor rotator cuff injuries will heal on their own with plenty of ice, rest, and daily shoulder exercises. If you do end up suffering a more involved injury, do literally the opposite of my dad and have it evaluated by a doctor. It may be one less story to tell at family gatherings, but you’ll be saving yourself a lifetime of pain.

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