Key Points

• The knowledge that a fifth quad muscle exists gives us a greater ability to be even more nuanced and detailed with our techniques.

• Our approach to the quadriceps muscles does not have to change except for this: Learning about anatomy and the muscle’s physiologies always guides how we work.

Here’s a fun fact: There’s a fifth quad muscle. Who knew? Well, maybe some of you. But I’m only now learning about this, which makes me think two things: (1) What we know about our anatomy is constantly being updated and evolving; and (2) What do we do with this information? I mean, not just that there’s a fifth muscle in a group of muscles that were named for the fact that there are four of them, but how does this change our approach? My first thought is more of an ongoing reflection about what we think we know—a great topic of conversation, but not the one I am focusing on for this article. My second thought is more of a question . . . And I have answers.

Processing New Information

Ultimately, these two points are related. If what we know is always changing, then what we do with that knowledge has to be part of the conversation. In this instance, we have always known the quadriceps muscles to be the vastus lateralis, the vastus intermedius, the vastus medialis, and the rectus femoris. The quads. Four of them. But now there’s a fifth. Where it is and what it does must influence how we work. 

Technically, there has been knowledge of a fifth quadricep since 2016 (or even before then, but this was when it was officially named). In a study of 26 cadavers, a fifth quadricep muscle, the tensor vastus intermedius (TVI), was found in 22 of them.¹ Technically, not everyone has a TVI. But 22 out of 26 is not a small percentage. Similar to the psoas minor or the palmaris longus, though, anomaly muscles get us thinking: What do they do? What does it mean for soft-tissue manipulation or dysfunction? And, perhaps most importantly, does the existence of a fifth quad muscle therefore change the name of the quads?

And so, I give you the tensor vastus intermedius. You will find this muscle (on those who have it) close to the hip and near its similarly named relative, the tensor fasciae latae. Its proximal attachment lies on the proximal and lateral surfaces of the shaft of the femur and/or the greater trochanter—depending on your source²—and its distal attachment veers medially and merges with the rest of the quad muscles just above the patella. It’s not a vast muscle, though. It looks like the anterior upper-leg version of the plantaris muscle—a burst of muscle fibers at the top with a long, tail-like tendon that reaches down to make contact.³ 

The actions of this little muscle are twofold, but not what you might expect. Instead of lending a hand in extending the knee alongside its siblings, it stands in the middle and sort of pulls them back in line if they get too cocky. Specifically, it may play a role in controlling the movement of the patella by counteracting the force of the vastus medialis. In other words, if the vastus lateralis gets too big for its britches, the TVI acts to reel it in and keep the patella in place. Also, it may act to exert tension on the aponeurosis of the vastus intermedius. Or, similar to how the TFL operates, it creates a tension in connective tissue structures to maintain a sense of stability—which we all need. 

What exactly does this mean for massage therapy? Our approach to the quadriceps muscles does not have to change except for this: Learning about anatomy and their respective physiologies always guides how we work. But because what we know is always shifting and moving, our ability to be fluid with the translation of what’s in our brains to what our hands do will always be essential. The knowledge that a fifth quad muscle exists gives us a greater ability to be even more nuanced and detailed with our techniques. Simultaneously, though, the person that’s on your table is still your best guide.

Adapting and Applying

Try this: With your client supine, have them situate the leg you are focused on so their knee is bent and that foot is on the table. Sit on their foot to help stabilize their leg. With both hands on either side of the knee, curl your fingers so your finger pads sink into the aponeurotic tissue just superior to the patella. Then start sliding from knee to hip methodically, working from medial to lateral or vice versa or both. Notice the density or pliability of their tissues. Check in with your client about what they feel. With this extra wisdom about the quads, spend a little time rapidly drawing short lines from the top of the patella to about mid-thigh with a decent amount of pressure. Then clasp your hands at the top of the leg near the hip, lean back, and give the TVI extra love. 

Knead the Fifth

Remember that educating your client is one of your most powerful techniques. Tell them about this new element that might be influencing their knee pain or muscle tension. Remind them you are always reading up on research and theories. And boost their confidence in who you are as a bodyworker. Your passion for this craft will be infectious. 

As for what we should call the quads now that we know more? Pentriceps? Quads 2.0? Vuads? What do you think? 

Notes

1. Karl Grob et al., “A Newly Discovered Muscle: The Tensor of the Vastus Intermedius,” Clinical Anatomy 29, no. 2 (March 2016): 256–63, https://onlinelibrary.wiley.com/doi/10.1002/ca.22680.

2. Wikipedia, “Tensor Vastus Intermedius Muscle,” last edited August 5, 2022, https://en.wikipedia.org/wiki/Tensor_vastus_intermedius_muscle.

3. Thomas Franchi, “Tensor Vastus Intermedius: A Review of Its Discovery, Morphology and Clinical Importance,” Folia Morphologica 80, no. 4 (2021): 792–8, https://journals.viamedica.pl/folia_morphologica/article/view/70802.