The M. Vastus Medialis (Vastus Medialis) is a muscle of the thigh anterior region. It is responsible for knee extension, medial patellar stabilization (VMO - important for patellar tracking). This muscle is one of 26 with official SENIAM-recommended surface EMG electrode placement. This page documents the exact electrode position, anatomical attachments and a standardized test movement based on Hermens et al. (2000).
Function
Knee extension, medial patellar stabilization (VMO - important for patellar tracking)
Hermens HJ, Freriks B, Disselhorst-Klug C, Rau G. Development of recommendations for SEMG sensors and sensor placement procedures. J Electromyogr Kinesiol. 2000;10(5):361-74.
Recording notes per Criswell 2011, site „Vastus Medialis (Oblique)“, p. 366
Placement type
Specific site The signal originates predominantly from this muscle.
Signal check
Seated: extend the knee; standing: partial squat.
Crosstalk from
rectus femoris · adductor longus · adductor magnus
The position above follows SENIAM; the crosstalk and artefact notes apply to surface recording of this muscle in general.
Print-ready for the lab or clinic: 75 pages of protocols (SENIAM + peer-reviewed), plus the SENIAM table, a placement checklist and a sensor comparison sheet as A4 sheets.
Anatomy
OriginMedial lip of the linea aspera, intertrochanteric line (distal)InsertionMedial border of the patella -> via patellar ligament to the tibial tuberosity
Test Movement
Terminal knee extension (last 15 degrees) against resistance
Illustration shows the left side; the set-up is mirrored for the right side.
MVC reference test (Konrad 2005)
Position
Seated, single-leg knee extension held between 90° and 70° knee flexion.
Fixation
Thigh and pelvis fixed on the seat; a strap at the ankle holds the knee angle.
Resistance
Fixed strap at the ankle, extension against it.
Konrad: an easy and beneficial exercise for all quadriceps muscles (rectus femoris, vastus lateralis, vastus medialis).
Konrad P. The ABC of EMG. Noraxon; 2005, p. 32. Konrad describes this test at group level; it applies to all muscles of the group. · Why and how to normalise to MVC
Clinical Applications
Common use cases for surface EMG measurement of the M. Vastus Medialis:
Knee rehabilitation (ACL, meniscus)
Quadriceps activation after surgery
Sports performance monitoring
Measure M. Vastus Medialis activity live
The electrode is placed — what next? easyEMG visualises muscle activity in real time, with SENIAM-compliant placement guidance, up to 4 channels at once and biofeedback training right afterwards.
In rehabilitation, the Vastus Medialis is typically recorded to track progress and retrain activation.
Where do I place the EMG electrode on the M. Vastus Medialis?
80% on line from ASIS to the anterior edge of the medial ligament. Orientation: Approx. 80 degrees to line ASIS-medial joint space. Based on the official SENIAM recommendations (Hermens et al. 2000).
Which test movement activates the M. Vastus Medialis?
Terminal knee extension (last 15 degrees) against resistance. This movement is part of the SENIAM protocol for standardized contraction verification.
Is the M. Vastus Medialis a SENIAM-recommended muscle?
Yes. The M. Vastus Medialis is one of 26 muscles for which the SENIAM project has published official surface EMG electrode placement recommendations.
Preview — open the 3D viewer to rotate the model and check neighbouring muscles.
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