Tyler Robbins Fitness

B.Sc. Biochemistry, Certified Strength and Conditioning Specialist (CSCS), Certified CrossFit Trainer (CCFT/CF-L3), USA Weightlifting Level 1

Filtering by Tag: Vastus Medialis

New muscle discovered - the Tensor of the Vastus Intermedius

*Rectus femoris dissected.* Source: https://en.wikipedia.org/wiki/Vastus_intermedius_muscle

The nomenclature or naming of your muscles oftentimes comes from the number of ‘heads’ a muscle subgroup has. For example, your biceps, triceps, quadriceps, etc. Your quadriceps, for example, is made up of the following 4 muscles: vastus medialis, vastus lateralis, rectus femoris, and vastus intermedius.

Well, it turns out in a collaborative effort between researchers in Switzerland and Australia, our vastus intermedius - which sits just beneath the rectus femoris in our thigh, actually has an additional head that they are naming the Tensor of the Vastus Intermedius.

“The quadriceps femoris is traditionally described as a muscle group composed of the rectus femoris and the three vasti. However, clinical experience and investigations of anatomical specimens are not consistent with the textbook description. We have found a second tensor-like muscle between the vastus lateralis (VL) and the vastus intermedius (VI), hereafter named the tensor VI (TVI). The aim of this study was to clarify whether this intervening muscle was a variation of the VL or the VI, or a separate head of the extensor apparatus. Twenty-six cadaveric lower limbs were investigated. The architecture of the quadriceps femoris was examined with special attention to innervation and vascularization patterns. All muscle components were traced from origin to insertion and their affiliations were determined. A TVI was found in all dissections. It was supplied by independent muscular and vascular branches of the femoral nerve and lateral circumflex femoral artery. Further distally, the TVI combined with an aponeurosis merging separately into the quadriceps tendon and inserting on the medial aspect of the patella. Four morphological types of TVI were distinguished: Independent-type (11/26), VI-type (6/26), VL-type (5/26), and Common-type (4/26). This study demonstrated that the quadriceps femoris is architecturally different from previous descriptions: there is an additional muscle belly between the VI and VL, which cannot be clearly assigned to the former or the latter. Distal exposure shows that this muscle belly becomes its own aponeurosis, which continues distally as part of the quadriceps tendon.”

So what does this mean? Not a whole lot. But going forward, bro-jokes and names may change - although not likely. For example, instead of shouting out ‘QUAD-ZILLA’ as you finish your last set of squats, you may want to shout ‘PENT-ZILLA’ or ‘QUNIT-ZILLA’ and instead of simply calling your thighs your ‘quads’ you may want to start referring to them as your ‘quints,’ although I doubt that name will catch on.

Learn all about your quadriceps

Source: http://en.wikipedia.org/wiki/Quadriceps_femoris_muscle

Source: http://en.wikipedia.org/wiki/Quadriceps_femoris_muscle

The quadriceps, or "quads", make up majority of the muscle of the anterior portion of the upper leg. The name quadriceps comes from the fact that there are 4 portions or "heads" that make up the quads.

The four heads of the quadriceps are:

  1. Rectus femoris (at right, in blue)
  2. Vastus Lateralis (at right, in yellow)
  3. Vastus Medialis (at right, in red)
  4. Vastus Intermedius (at right, in green)

The Rectus Femoris attaches on the ilium (hip) and covers most of the other 3 heads. The Vastus Lateralis, Medius, and Intermedius all originate on the upper part of the femur. All 4 heads insert, or attach, on the tibial tuberosity just below the knee.

All 4 heads of the quadriceps extend the lower leg at the knee, however, since the rectus femoris is the only head that attaches to the hip, it is the only head that works on flexing the upper leg at the hip.


  • Knee Extension
  • Hip Flexion (rectus femoris only)

Hip Flexion

Knee Extension

Knee Cap


Have you ever thought about why you have a knee cap, also known as the patella? It is a bit odd if you think about it. Your knee cap is, essentially, a free-floating disc of bone. The truth of the matter, however, is that the knee cap is a very important and beneficial tool to improve the effectiveness of the quadriceps.

The quadriceps muscles make up the patella tendon, that passes over the kneecap and attaches to the tibia, just below the knee. Since the tendon passes over the patella (kneecap), when the quadricep muscle pulls on the tibia to extend the leg at the knee, the patella increases the mechanical advantage of the knee.

If you think back to your basic physics lessons in school, the further the generating force (patella tendon) is from the centre of rotation (the knee itself), the less force is required to move the object. This is the same applied principle when using a lever arm. If you were to lift a heavy object, such as a piece of furniture using a lever, the longer the lever, the easier (less overall force) it would be to move said object.