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Tuesday, June 6, 2023

Quadriceps - Vastus Muscles

Brent Brookbush

Brent Brookbush


Human Movement Science & Functional Anatomy of the: Quadriceps: Vastus Muscles

by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS


The Rectus Femoris is covered in a separate article due to its origin on the anterior inferior iliac spine. This separate origin results in a separate action, function, fascial integration, and behavior in postural dysfunction.

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Beautiful model of the upper thigh. Visible from right to left is the Tensor Fasciae Lata , Vastus Lateralis (inferior), Rectus Femoris , Sartorius , Pectineus and Adductor Longus - http://www.3dscience.com/img/5-products/3d-models/female/muscles/zygote-female-muscles-2.jpg

What's in a name:

  • Quadriceps - originating from the Latin root "quad" and "ceps", in reference to "four heads", and often termed "quadriceps femoris" relating to "four-headed muscle of the femur."
  • Vastus: The Latin root for "huge" or "enormous". The adjectives, lateralis, medialis, and intermedius refer to their location relative to one another, as in lateral, medial, and in-between.

Cadaver Dissection of Quadriceps: Rectus femoris reflected for viewing vastus intermedius - http://www.rvuanatomy.com/uploads/1/3/4/5/13457421/afc1d_animated.gif

Vastus Lateralis:

  • Origin: Proximal part of the intertrochanteric line, anterior and inferior borders of the greater trochanter, lateral lip of the gluteal tuberosity, proximal half of the lateral lip of linea aspera, and lateral intermuscular septum (11).
  • Insertion: Proximal border of the patellar ligament to the tuberosity of the tibia, and to the capsule of the knee and meniscus via patellar retinacular fibers (3, 11).
    • The vastus lateralis is a superficial muscle, only covered by the thickening of the fascia lata known as the iliotibial band or iliotibial tract. The vastus lateralis wraps around the femur abutting the lateral intermuscular septum and biceps femoris posteriorly and the vastus intermedius medially - the most medial fibers being partially covered by the rectus femoris. The vastus lateralis may have fascial slips investing in the iliotibial tract, and may further contribute fascial slips to the lateral retinaculum and lateral collateral ligaments distally.
    • Palpation of this muscle can be achieved by having your partner lay in a side-lying position with your hand placed on their lateral thigh. Have your partner extend and relax the knee as you feel the vastus lateralis contract under your hands. Follow the muscle to its proximal and distal ends. (14).
  • Nerve: Femoral nerve via the lumbar plexus originating from nerve roots L2, L3, and L4.
  • Action:
    • Knee: Extension, may contribute to tibial external rotation.

Cross Section of thigh - Note the relative size and thickness of the Quadriceps and the lateral and medial intermuscular septum - https://bedahunmuh.files.wordpress.com/2010/05/thigh-serial-cross-section.jpg

Vastus Intermedius:

  • Origin: Anterior and lateral surfaces of the proximal 2/3 of the body of the femur, distal half of the linea aspera, and the lateral intermuscular septum (11).
  • Insertion: Proximal border of the patellar ligament to the tuberosity of the tibia (11).
    • The vastus intermedius lies deep to the rectus femoris, abutting the vastus medialis and wrapping around the femur, deep to the vastus lateralis, to abut the lateral intermuscular septum.
    • Palpation of this muscle can be achieved by palpating deep to the rectus femoris . With your partner laying in supine, have them tightly extend their knee and flex their hip to lift the leg a couple of inches off the table. Once you have clearly defined the rectus femoris, have your partner relax, and see if you can feel past the rectus femoris to a second layer of tissue (denser layer). Note: this is a little easier to achieve in the septum 3- 5 inches above the knee between the vastus lateralis and vastus intermedius.
  • Nerve: Femoral nerve via the lumbar plexus originating from nerve roots L2, L3 and L4.
  • Action:
    • Knee: Extension.

Vastus Medialis:

  • Origin: Distal half of the intertrochanteric line, medial lip of the linea aspera, proximal part of the medial supracondylar line, tendons of the adductor longus and adductor magnus, and medial intermuscular septum (11).
  • Insertion: Proximal border of the patellar ligament to the tuberosity of the tibia, and to the capsule of the knee and meniscus via patellar retinacular fibers (3, 11).
    • The distal half of the vastus medialis is the only superficial aspect of this muscle, as it is seen as a "teardrop" shape that invests in the patellar tendon. The proximal half of this muscle is actually covered by the rectus femoris and sartorius . The posterior half of this muscle abuts the medial intermuscular septum
    • Palpation of this muscle can be achieved by placing a bolster between the knees in side-lying. Palpate the medial aspect of the thigh just superior to the patella. You can feel the bulbous shape of this muscle. You can also palpate the sartorius and rectus femoris and note how they border the vastus medialis creating the teardrop shape.
  • Nerve: Femoral nerve via the lumbar plexus originating from nerve roots L2, L3, and L4.
  • Action:
    • Knee: Extension.

Integrated Function:

  • Stabilization:
    • Tibiofemoral Joint
    • Patellofemoral Joint
    • Vastus lateralis may contribute to tibiofibular joint stability
  • Eccentrically Decelerates:
    • Knee flexion
    • Vastus Medialis: may restrict tibial external rotation and resists valgus forces at the knee
    • Vastus Lateralis: may restrict tibial internal rotation and varus forces at the knee, may also restrict adduction via fascial slips in the iliotibial tract.
  • Synergists:
    • Knee Extension: The most obvious and pivotal role that the vastus muscles play is an extensor of the knee (eccentric control of flexion). They act synergistically with the rectus femoris and to a lesser extent the articularis genu (which may play a larger role in tensing the anterior capsule of the knee).
    • Tibial External Rotation: The vastus lateralis may contribute to tibial external rotation via its fascial integration with the iliotibial band and the lateral fascial structures of the knee. This implies a synergistic relationship with the tensor fasciae latae , biceps femoris , and lateral gastrocnemius.
    • Tibial Internal Rotation (medial stabilization): The vastus medialis may contribute to tibial internal rotation, or at the very least, assist in medial stabilization of the knee and medial patella. The fibers most often referred to in regard to this role are the vastus medialis obliquus; a group of fibers with an oblique (diagonal) axis that has a superomedial force vector. This implies a synergistic relationship with the medial rotators of the knee including the sartorius , gracilis , popliteus , medial gastrocnemius, and semitendinosus and semimembranosus .
    • Reciprocal Inhibition: "Activation " of the vastus medialis is common practice in rehab and sports performance settings; however, many of the exercises utilized have been called into question due to the inability of any exercise to isolate one quadriceps muscle from another, and or the exercise selected playing a role in activating over-active synergists (ex. squeezing a ball between the knees during extension increases adductor activity and may increase femoral internal rotation and adduction moments during subsequent activity). One preliminary study did highlight an interesting method of increasing activity which alludes to altered reciprocal inhibition. The functional antagonist of the vastus medialis obliquus is actually the short head of the biceps femoris (a commonly over-active muscle), as demonstrated in a study by Hasagawa et. al. in which stretching of the biceps femoris increased VMO activity during a subsequent extension exercise (15)

Iliotibial "band" - Note how the vastus lateralis is bound to this tissue on the left of this picture http://www.rvuanatomy.com/uploads/1/3/4/5/13457421/afc1e_animated.gif


  • This muscle plays a role in the arthrokinematics of the knee and hip joints.
    • Hip: The ITB is invested by fascial slips from the vastus lateralis (VL) implying that the VL may play a role in tensing the ITB and eccentrically decelerating adduction of the hip.
    • Knee: The vastus muscles as a whole play a role in compression and anterior translation of the tibia on the femur. The vastus medialis and vastus lateralis may contribute to tension in the anteromedial and anterolateral capsule and stability of the meniscus (3). Further, the vastus lateralis may contribute to a valgus force, while the vastus medialis plays a role in producing a varus force. Although it cannot be said that the quadriceps will produce medial or lateral rotation of the tibia independently, they may play a role as synergists, as discussed above.
    • Patellofemoral Joint: The vastus muscles play an intricate role in patellar tracking. While the gross line of pull (referred to as the quadriceps angle or Q-angle), is superolateral this is in large part due to the larger cross-section and size of the vastus lateralis (contributing to lateral glide). The vastus lateralis may also medially tilt and laterally rotate the patella, although this actually a function of the lateral glide combined with the architecture of the trochlea of the femur. The vastus medialis plays a role in balancing the lateral force, specifically those fibers referred to as the vastus medialis obliquus (VMO). Clinically, the VMO's ability to medially glide the patella has been the focus of exercise intervention, but due to the inability to practically isolate this muscle, it is likely that a global approach (correcting activity and length of the hip, knee, and ankle) to aligning the femur, tibia, and patella is more effective for correcting dysfunction and pathology. As mentioned above, improving mechanics and altering muscle activity may improve function (stretching the biceps femoris increases VMO activity). The quadriceps (including the rectus femoris ) may posteriorly tip the patella, but careful evaluation usually implicates an adaptively shortened and over-active rectus femoris causing dysfunction as opposed to the vastus medialis and vastus intermedius which may be prone to under-activity.

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Note the oblique angle of the VMO as it tracks from sartorius to patella – http://www.sciencephoto.com/online-courses/online-courses/image/454917/350wm/C0126318-cadaver_dissection-SPL.jpg

Fascial Integration:

My Fascial Hypothesis: Large fascial sheaths not only play a role in the transmission of mechanical force but may also play a role in dictating the function of muscular synergies. This is likely caused by reducing or increasing the tone of invested musculature via reflex arcs formed between mechanoreceptors embedded in the connective tissue and the attached musculature. In this way, my view of fascia differs slightly from the noted expert on the subject Tom Myers. I think of these large fascial sheaths (specifically the thoracolumbar fascia, iliotibial band, and abdominal fascial sheath) as nature's "motherboard." A place for mechanical information to be communicated to the nervous system for more efficient recruitment of the muscular system. Despite having a slightly different philosophy it does not change the fact that fascia plays an important communicative role in the human body and we have Tom Myers to thank for his work.

Medial Knee with Patellar Tendon, LCL and Pes Anserinus Tendons attached
Caption: Medial Knee with Patellar Tendon, LCL and Pes Anserinus Tendons attached

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Medial Knee with Patellar Tendon, LCL and Pes Anserinus Tendons attached – http://www.visionmedicavirtual.com/online-courses/online-courses/gallery/b_IS.0908.001.08.jpg

  • TFL/VL/ITB Complex (Tensor fascia latae , vastus lateralis, iliotibial band) – The tensor fascia latae (TFL) uses the iliotibial band (ITB) as a tendon. The ITB is invested by fascial slips from the vastus lateralis (VL). These fascial slips from the VL extend above the hip giving it a role in resisting adduction and the distal slips give it a role in increasing tension in the lateral structures of the knee. In essence, the fascial slips from VL to ITB allow it to assist in the same joint actions that the TFL can produce. The distal attachment of the ITB creates a fascial network that interconnects the patellar tendon, the lateral collateral ligament at the knee, the anterior tibiofibular ligament, and the tendon of the bicep femoris. During tibial external rotation and/or lateral knee stabilization the TFL is activated to increase tension in the iliotibial band along with the vastus lateralis. The TFL/ITB/VL complex along with the biceps femoris and lateral gastrocnemius comprise the functional group that laterally stabilizes & externally rotates the knee. Further, in postural dysfunction, pattern overload of this complex may lead to vastus lateralis trigger points, and the superficial fascia of the vastus lateralis becoming bound to an iliotibial band that has been pulled tight and shifted anteriorly by a TFL that is short and overactive. Because of these factors, it may be necessary to add self-administered static release techniques for the vastus lateralis, and myofascial shear techniques for the ITB to a routine aimed at returning optimal TFL neuromuscular efficiency. Another potential relationship may exist between the TFL's nasty cousin - the gluteus minimus  - and the vastus lateralis, whose attachments border one another.
  • Vastus Medialis to Adductors: The vastus medialis does have fibers that originate on the adductor longus and adductor magnus tendons. This may imply a functional synergy, but honestly, I cannot imagine the implication. Generally, these muscles do not work synergistically nor do they behave similarly in postural dysfunction. There may be a relationship that needs further study regarding the stabilization function of vastus medialis activity on the adductor tendons or the effect adductor strains have on vastus medialis muscle activity, but we'll have to wait for further information. Rest assured I will be paying closer attention to this relationship in practice.

Cadaver dissection of the lower extremity – http://myampgoesto11.tumblr.com/online-courses/online-courses/post/16940081948/day-5-of-cadaver-dissection

Behavior in Postural Dysfunction:

The vastus muscles do not fit neatly into any one postural dysfunction although they may play a role in both lumbopelvic hip complex dysfunction and lower leg dysfunction . In general, we see altered vastus muscle recruitment strategies relative to knee dysfunction, pain, and pathology. This may be driven by several factors. As mentioned above the vastus lateralis may play a role in tibial external rotation/femoral internal rotation, increased valgus forces, and lateral tracking of the patella. These are the same joint actions and forces that have been described in everything from ACL injury to lateral knee pain (runner's knee) to patellofemoral pain syndrome. We need not look any further than the imbalance between the cross-section and size of the vastus lateralis and vastus medialis to explain these common pathologies; however, recently more attention has been given to a global approach. It could be that the compensation patterns noted in LPHCD and LLD, specifically the inability to eccentrically control femoral internal rotation and or pronation of the subtalar joint (3), are responsible for the imbalance and change in muscle activity between the vastus lateralis and vastus medialis, and additionally the vastus intermedius and rectus femoris. This may be the result of mechanical forces, or the relationships between knee extensors and flexors and altered patterns of reciprocal inhibition noted above. Further, research has shown that increased intra-articular pressure (swelling) alone can reflexively inhibit quadriceps activity (3). The most notable mechanical outcome of this dysfunction is actually the loss of terminal extension (0 to -5º of flexion). It is rare that quadriceps activity would reduce knee flexion extensibility (tested with hip flexed). Most often reductions in knee flexion have more to do with rectus femoris adaptive shortening and over-activity, capsule tightness (either from swelling or adaptive shortening), and or arthrokinematic dyskinesis.

In Upper Body Dysfunction (UBD) the vastus muscles play no significant role.

In Lumbo Pelvic Hip Complex Dysfunction (LPHCD)  the vastus lateralis may be over-active as a function of the TFL/VL/ITB synergy discussed above and over-activity and adaptive shortening of the hip flexor musculature as part of this dysfunction. This synergy may also play a role in Sacroiliac Joint Dysfunction (SIJD)  on the side of the anteriorly rotated innominate.

In Lower Leg Dysfunction (LLD)  we may find the best explanation for under-activity of the vastus medialis along with the tibial internal rotators (relative increase in length due to femoral internal rotation and tibial external rotation). Tibial internal rotator activation may be somewhat effective for increasing activity in the vastus medialis by improving tibial femoral mechanics. Below you will find further techniques for increasing activation of the vastus muscles paired with progressions and cueing to stimulate the activity of under-active muscles in this dysfunction. This dysfunction also implies over-activity of the biceps femoris contributing to reciprocal inhibition of the VMO and an increase in activity of the tibial external rotators including the TFL/VL/ITB complex discussed above. In short, all vastus muscles may become under-active due to increased intra-articular pressure in the knee, but most commonly we see an alteration in activity including over-activity of the rectus femoris and vastus lateralis, and under-activity of the vastus medialis. It is tough to determine the relative activity of the vastus intermedius due to its location deep to the rectus femoris, but then again all techniques directed at the quads will result in some change to the vastus intermedius and the techniques below have proven to be effective. As limitations in knee flexion are rare (except in the post-surgical knee) when the hip is flexed (reducing the involvement of the rectus femoris ) stretching the vastus muscles is not recommended. Release techniques may be used to reduce adhesion, over-activity and trigger points in the lateral and anterior thigh, and activation techniques for the quadriceps (specifically VMO activation) are recommended to improve terminal extension strength with cues to reinforce tibial internal rotation and femoral external rotation (foot slightly rotated inward - 5th metatarsal pointing forward, and glute activation). Studies have shown better activation of the quadriceps in closed-chain or weight-bearing activities, implying that progression to these techniques should occur as soon as is appropriate for the individual (3).

Clinical Implications:

  • Anterior knee pain
  • Chondromalacia Patella
  • Patellofemoral pain syndrome
  • Pes anserinus tendonitis
  • Pes anserinus bursitis
  • Medial knee pain
  • Patella Alta
  • Lateral knee pain
  • Iliotibial band syndrome
  • Low back pain
  • Sacroiliac joint pain

Signs of Altered Length/Tension and Tone:

  • Overhead Squat:
    • Anterior Pelvic Tilt: Short/Over-active TFL/VL/ITB
    • Excessive Forward Lean: Short/Over-active TFL/VL/ITB and Decreased Quad Strength
    • Knees Bow In: Long Underactive/Vastus Medialis
    • Feet Turn Out: Short/Over-active TFL/VL/ITB, Long/Underactive Vastus Medialis
  • Goniometric Assessment
  • Decreased Tibial Internal Rotation < 20°
  • Decreased Knee Extension < 0 to -5°
  • Decreased Knee Flexion (Prone with hip flexed) < 135 -150°
  • Quadriceps Trigger points:
    • See the link below for common trigger point locations and referral pain patterns for active trigger points.
    • As trigger points may be closely related or synonymous with acute over-activity at the motor point, you may find this article interesting - Motor Point Map

Exercises Involving Vastus Muscles:

Rectus Femoris Self-administered Static Release (Note: Trigger points felt in this technique may also implicate vastus intermedius, articularis genu, or sartorius trigger points)

Anterior Thigh Self-administered Active Release (Note: Restrictions felt in this technique may actually be related to the vastus intermedius, sartorius, or anterior fascia lata)

Vastus Lateralis Self-Administered Release:

Iliotibial Band Self-administered Myofascial Shear:

Quad Sets and Progressions:

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VMO Activation (Total Knee Extension):

VMO Activation Progression:


  1. Phillip Page, Clare Frank Robert Lardner Assessment and Treatment of Muscle Imbalance: The Janda Approach © 2010 Benchmark Physical Therapy, Inc., Clare C. Frank, and Robert Lardner
  2. Dr. Mike Clark & Scott Lucette, “NASM Essentials of Corrective Exercise Training” © 2011 Lippincott Williams & Wilkins
  3. Donald A. Neumann, “Kinesiology of the Musculoskeletal System: Foundations of Rehabilitation – 2nd Edition” © 2012 Mosby, Inc.
  4. Michael A. Clark, Scott C. Lucett, NASM Essentials of Personal Training: 4th Edition, © 2011 Lippincott Williams and Wilkins
  5. Leon Chaitow, Muscle Energy Techniques: Third Edition, © Elsevier 2007
  6. Tom Myers, Anatomy Trains: Second Edition. © Elsevier Limited 2009
  7. Shirley A Sahrmann, Diagnoses and Treatment of Movement Impairment Syndromes, © 2002 Mosby Inc.
  8. David G. Simons, Janet Travell, Lois S. Simons, Travell & Simmons’ Myofascial Pain and Dysfunction, The Trigger Point Manual, Volume 1. Upper Half of Body: Second Edition,© 1999 Williams and Wilkens
  9. Cynthia C. Norkin, D. Joyce White, Measurement of Joint Motion: A Guide to Goniometry – Third Edition. © 2003 by F.A. Davis Company
  10. Cynthia C. Norkin, Pamela K. Levangie, Joint Structure and Function: A Comprehensive Analysis: Fifth Edition © 2011 F.A. Davis Company
  11. Florence Peterson Kendall, Elizabeth Kendall McCreary, Patricia Geise Provance, Mary McIntyre Rodgers, William Anthony Romani_, Muscles: Testing and Function with Posture and Pain: Fifth Edition © 2005 Lippincott Williams & Wilkins_
  12. Brent Brookbush, Fitness or Fiction: The Truth About Diet and Exercise © 2011 Brent Brookbush - http://www.amazon.com/Fitness-Fiction-Truth-About-Exercise/dp/0615503012
  13. Carolyn Richardson, Paul Hodges, Julie Hides. Therapeutic Exercise for Lumbo Pelvic Stabilization – A Motor Control Approach for the Treatment and Prevention of Low Back Pain: 2nd Edition (c) Elsevier Limited, 2004
  14. Andrew Biel, Trail Guide to the Human Body: 4th Edition, © 2010
  15. Hasagawa K, Hori S, Tsujita J, Dawson M. Effects of Stretching Exercises on Vastus Medialis and Vastus Lateralis. Med Sci Sports and Exerc. 2001(33)5 S10

© 2014 Brent Brookbush

Questions, comments, and criticisms are welcome and encouraged