Muscles of lower extremity
|Latin||Musculus vastus medialis or musculus vastus internus|
|Origin||Medial side of femur|
|Vastus medialis muscle|
|Anatomical terms of muscle|
The Vastus Medialis muscle originates from a continuous line of attachment on the femur, which begins on the front and middle side (anteromedially) on the intertrochanteric line of the femur. It continues down and back (posteroinferiorly) along the pectineal line and then descends along the inner (medial) lip of the linea aspera and onto the medial supracondylar line of the femur. The fibers converge onto the inner (medial) part of the quadriceps femoris tendon and the inner (medial) border of the patella. 
The Vastus Medialis is one of five muscles that reside in the anterior compartment of the thigh. The vasti muscles appear to act largely in a co-ordinated manner throughout the control of knee extension. The vastus medialis contributes to correct tracking of the patella and characteristics of the vastus medialis, including its angle of insertion, correlate with presence of patellofemoral joint pain. However, this syndrome is complex and definitive evidence of causality has not yet been published.
A division of the vastus medialis muscle into two populations of fibers has been hypothesized:
- one population is thought to be long and relatively inline with the quadriceps ligament: the vastus medialis longus (VML)
- the other is thought to be shorter and more obliquely oriented with respect to the quadriceps ligament: the vastus medialis obliquus (VMO).
At the present time, there is insufficient evidence to conclusively confirm or deny this hypothesis. For clinical and rehabilitation purposes, the vastus medialis is often referred to simply as the VMO in reference to its potentially important role in correct patellar tracking and prevention of patellofemoral joint syndrome.
Knee pain is thought to be primarily associated with specific quadriceps muscle weakness or fatigue, especially in the VMO. It is known that fatigue can be caused by many different mechanisms, ranging from the accumulation of metabolites within muscle fibers to the generation of an inadequate motor command in the motor cortex. Misfiring and fatiguing of the VMO causes mal-tracking of the patella and subsequent damage to surrounding structures creating increased force on the knees, often resulting in injuries such as patellofemoral pain syndrome, anterior cruciate ligament rupture, chondromalacia, and tendinitis. Through the use of electromyography, researchers can evaluate and record the electrical activity produced by the skeletal muscle of the VMO to analyze the biomechanics and detect any possible abnormalities, weakness, or fatigue. With an analysis of muscle activity of the VMO through the use of electromyography, proper rehabilitative plans and goals can be established to not only correct the already established abnormality, but even prevent such injuries if tested sooner. Preventing injuries is crucial as well as teaching proper training techniques to ensure there are no valgus collapse forces causing unplanned stress on other structures of the knee, causing asymmetry, and predisposing that individual for injury.
- Drake, Richard; Vogl, Wayne; Mitchell, Adam; Gray, Henry David (2009). Gray's Anatomy for Students (2 ed.). Philadelphia, PA: Churchill Livingstone. ISBN 978-0443069529.[page needed]
- Sheehan, FT; Borotikar, BS; Behnam, AJ; Alter, KE (2012). "Alterations in in vivo knee joint kinematics following a femoral nerve branch block of the vastus medialis: Implications for patellofemoral pain syndrome". Clinical biomechanics 27 (6): 525–31. doi:10.1016/j.clinbiomech.2011.12.012. PMC 3328589. PMID 22244738.
- Jan, MH; Lin, DH; Lin, JJ; Lin, CH; Cheng, CK; Lin, YF (2009). "Differences in sonographic characteristics of the vastus medialis obliquus between patients with patellofemoral pain syndrome and healthy adults". The American journal of sports medicine 37 (9): 1743–9. doi:10.1177/0363546509333483. PMID 19521000.
- Smith, TO; Nichols, R; Harle, D; Donell, ST (2009). "Do the vastus medialis obliquus and vastus medialis longus really exist? A systematic review". Clinical anatomy 22 (2): 183–99. doi:10.1002/ca.20737. PMID 19090000.
- Enoka, RM; Duchateau, J (2008). "Muscle fatigue: what, why, and how it influences muscle function". The Journal of Physiology 586 (1): 11–23. PMID 17702815.
- Lefebvre, R; Leroux, A; Poumarat, G; Galtier, B; Guillot, M; Vanneuville, G; Boucher, JP (2006). "Vastus medialis: anatomical and functional considerations and implications based upon human and cadaveric studies". Journal of Manipulative and Physiological Therapeutics 29 (2): 139–144. PMID 16461173.
This article uses anatomical terminology; for an overview, see anatomical terminology.
|Wikimedia Commons has media related to Vastus medialis.|
- The KNEEguru - educational site packed with knee content with sections on the quadriceps muscle
- Origin, insertion and nerve supply of the muscle at Loyola University Chicago Stritch School of Medicine
- Cross section at UV pembody/body18b