To win a trip to Hawaii: “Can I buy an ‘H’ please…”    









Further proof that anatomical nomenclature severely lacks creativity - musculus subscapularis literally means “muscle under the scapula”…which is, like, where it lives. #captainobvious  All the cool kids just call it “subscap” though. And when two or more subscaps are gathered together, I believe proper plural would be subscapulares. <- {fact check needed}

In terms of shape, region-relative size, and function – subscap is essentially the “glute medius” of the shoulder girdle. Think about it. Large fan-shaped muscle belly contributes significant stability to the glenohumeral joint. Oh, and its innervated by its own set of nerves (upper and lower subscapular nerves). Very glute-ish.

Just wait until swimsuit season approaches and the gym mirrors are full of people toning up their subscaps …or you start seeing 6-minute ‘Subscaps of Steel’ workout videos. OK, maybe subscap isn’t as red carpet as the gluteus’. But I’m trying to make a point here.

Maybe one reason subscap doesn’t get the same aesthetic appreciation the glutes do, is because it is completely hidden underneath the scapula, like an emo high schooler locked away in their dark bedroom. Probably hasn’t cleaned its fossa in months. Playing video games with his only friend, serratus anterior. And only gets dragged out into the sunlight with an annoyed look on his face in the very end range of shoulder elevation, scapular upward rotation and abduction.

{last known photo of subscap}

Subscap not only makes up over 50% of the combined cross-sectional muscle mass of our rotary cup rotor cuff rotator cleft, but it’s tendinous attachment contributes significant structural and functional stability to the glenohumeral joint. A substantial footprint extending from the lesser trochanter (of the humerus, not the femur – just FYI), to the greater tubercle and bicipital groove darn near creates the entire anterior aspect of the GH capsule. So aside from contributing to the sexier osteokinematic motions of shoulder internal rotation and abduction - subscap provides humeral head depression and significant defense to anterior humeral head displacement.

Interesting to note, that the upper and lower portions of subscapularis function independently.

“Oh, thaaaaaaat’s why it has TWO of its own nerves”.

Essentially the upper portion of subscap becomes more and more active for stability, humeral head position, and internal rotation force in higher ranges of shoulder abduction, compared to the lower portion.1,2  Meaning, you overhead throwers out there demand A LOT of eccentric work from the upper subscap. Based on Decker et al, the best rehab exercise to target the upper fibers of subscap for such throwers is the cross-adduction diagonal exercise; and the exercise that recruited BOTH portions of subscap the best was the dynamic hug (and push-up plus).

Diagonal exercise1

Dynamic hug1

It is also fascinating to learn that isolated subscap tears are generally non-traumatic and have more to do with intrinsic degeneration from poor loading/use and anterior-superior impingement.3 Guess that is a cautionary tale to all of the moody teenagers out there, sitting in their rooms playing video games with serratus right now, huh? …or maybe these teenagers are misunderstood and just need more dynamic hugs.

Subscap tears are also often directly correlated to supraspinatus tears - the most common type of rotator cuff injury, which is a common finding as age increases and commonly found to be common.4 Did I mention rotator cuff tears are common? Yep, even in pain-free, asymptomatic folks. So just because your imaging shows mild-to-moderate e’rything does NOT mean it needs to be surgically repaired.

But this subscap-supraspinatus cuff tear association can be explained a few ways – 1) positional = the same position/mechanism of supraspinatus injury also puts subscap in a hairy position, 2) stress-strain relationship = there is increased strain forced upon subscap when supraspinatus peaces out, or 3) shared/adjacent capsular attachments form a very direct physical association.

There are also two ends of the surgical spectrum to foster some deep thoughts on subscap. First, surgical repair of a full-thickness tear of subscap is often imperative to restore anterior stability – no amount of isometrics or theraband IR exercise will restore this stability. BUT, then consider that subscap is sometimes sacrificed during total shoulder arthoplasty. Like, not re-attached. I picture surgeons basically saying...

“Subscap, we don’t need you anymore. I’ve just inserted a NASA-grade polycarbon robot joint that is stabile enough on it’s own. We never really needed you for shoulder motion in the past anyways, we just used you for your anterior capsule stability…and video games.”

Total burn. {evil laughter}


Evil laughter aside, both of these surgical scenarios seem to support the notion that subscap is much more dynamic stabilizer and humeral head stabilizer, than shoulder mover. We’ve got sexier muscles to stare at in the mirror for shoulder motion – oh hey pec, lat, teres, deltoid ;)

Lastly, let’s put a rehab and dry needling lens on things. I mean, this is the iDryNeedle blog, right?! So I offer FIVE clinical scenarios and THREE challenges to consider as a dry needling clinician.

5 clinical scenarios to consider treating subscap:

  1. Throwers – they demand the most out of the cuff, and subscap specifically. Think about positional/mobility, force production/torque, and volume demands for these patients.
  2. Previous shoulder instability – whether there was previous surgical intervention or not. Unfortunately once the integrity of the shoulder joint complex is compromised, the muscular stabilizers have a long road ahead.
  3. Posterior shoulder pain – yep, a common muscular referral pattern for subscap goes straight to the posterior capsule.
  4. Adhesive capsulits – you need to know cause and stage of a frozen shoulder, but subscap is magical for the right patients.
  5. Overhead lifters – initially I was thinking CrossFitters with any overhead press or catch of a snatch or jerk, but honestly very similar applies to grandma reaching to put a coffee mug on the top shelf.

3 subscap-specific challenges:

  1. Be safe. You probably saw this one coming, but it has to be said. Don’t just start inserting needles in the axilla or near the thorax without proper training.
  2. Be specific. Of all the incredibly valuable content I just provided, we touched on the fact that upper and lower subscap function separately. Use this type of info to target specific portions of the muscle based on patient presentation, positional provocation, and treatment goal.
  3. Reinforce changes. I always recommend reinforcing DN changes with corrective strategies for best outcomes, but I have found stabilizing muscles specifically require immediate, structured, loaded reinforcement. Think stability in different shoulder positions, not theraband internal rotation with a towel roll.


Oh, and give someone a dynamic hug today!
Sincerely sarcastic,

Paul Killoren PT, DPT




1) Decker, Michael J., et al. "Subscapularis muscle activity during selected rehabilitation exercises." The American journal of sports medicine 31.1 (2003): 126-134.

2) Kronberg M, Nemeth G, Brostrom LA: Muscle activity and coordination in the normal shoulder: An electromyographic study. Clin Orthop 257: 76– 85, 1990 22. Liu J, Hughes RE, Smutz WP, et al: Roles of the deltoid and rotator cuff

3) Longo, Umile Giuseppe, et al. "Subscapularis tears." Rotator Cuff Tear 57 (2012): 114-121.

4) Tempelhof, Siegbert, Stefan Rupp, and Romain Seil. "Age-related prevalence of rotator cuff tears in asymptomatic shoulders." Journal of shoulder and elbow surgery 8.4 (1999): 296-299.