Vastus medialis
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| Vastus medialis | |
|---|---|
| Vastus medialis | |
 | |
| Muscles of lower extremity | |
| Gray's | subject #128 471 |
| Origin | femur |
| Insertion | patella |
| Artery: | femoral artery |
| Nerve: | femoral nerve |
| Action: | extends leg |
The vastus medialis, often called the 'teardrop' muscle, is a medially located muscle of the quadriceps.
Function
Vastus medialis has been widely reported to be responsible for extending the leg the last 10%, however this commonly held claim has no basis, indeed there is a reasonable body of evidence to the contrary. The vasti instead appear to act largely in a co-ordinated manner throughout the control of knee extension.
Much has been made of the ability of the Vastus Medialis to translate the patella medially, however since approximately 70% of the contractile fibres attach directly to the common extensor tendon (which then inserts centrally to the superior patella) the functional ability to achieve this goal may be overstated, and is likely dwarfed by the bony congruence of the patella in the trochlea notch. Some authorities maintain there is a separate aspect to the Vastus Medialis muscle - the "Vastus Medialis Obliquus" or more commonly the "VMO" which is reported to have a more oblique or horizontal orientation to the bulk of the remainder of the muscle thereby disposing it to be better able to 'pull' the patella medially. Unfortunately careful inspection of many cadavers reveals that the fibres of the Vastus Medialis are largely parallel and there is no significant separate aspect of the contractile fibres fitting this description which would suggest it is time to lay this clinical myth to rest.
Often medical and other allied health practitioners suggest improving the strength and/or activation of this muscle as a strategy in the treatment of anterior knee pain - sometimes called runner's knee.
Lunges are an exercise sometimes used to target this muscle.
Origin and insertion
It arises from the lower half of the intertrochanteric line, the medial lip of the linea aspera, the upper part of the medial supracondylar line, the tendons of the Adductor longus and the Adductor magnus and the medial intermuscular septum.
Its fibers are directed downward and forward, and are chiefly attached to an aponeurosis which lies on the deep surface of the muscle and is inserted into the medial border of the patella and the Quadriceps femoris tendon, an expansion being sent to the capsule of the knee-joint.
Relations
The Vastus medialis and Vastus intermedius appear to be inseparably united, but when the Rectus femoris has been reflected a narrow interval will be observed extending upward from the medial border of the patella between the two muscles, and the separation may be continued as far as the lower part of the intertrochanteric line, where, however, the two muscles are frequently continuous.
Additional images
 Right femur. Posterior surface. |
 Muscles of the iliac and anterior femoral regions. |
 The femoral artery. |
External links
- LUC vasm
- Cross section at UV pembody/body18b
- Vastus+medialis+muscle at eMedicine Dictionary
- PTCentral
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
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nl:Musculus vastus medialis ja:内側広筋 sv:Vastus medialis
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
