Vastus medialis (vastus internus)

The vastus medialis (aka vastus internus), often called the ‘teardrop’ muscle, is a medially located muscle of the quadriceps.

Function

The vasti appear to act largely in a co-ordinated manner throughout the control of knee extension.

“Runner’s Knee”

Often medical and other allied health practitioners suggest improving the strength and/or activation of this muscle as a strategy in the treatment of Patello-femoral Pain Syndrome – sometimes called runner’s knee. The biomechanical cause of patellofemoral pain syndrome is unknown and may have more to do with weakness of extensors of the hip (i.e. gluteus maximus), which causes subsequent unusual internal rotation of the femur. Patello-femoral syndrome can also be caused by an injury, a misaligned patella, or changes underneath the patella. The primary symptom of this syndrome is typically knee pain when squatting, sitting, jumping, and ascending and descending stairs. It can also cause the knee to give out suddenly and popping or cracking noises within the knee.

Lunges are an exercise sometimes used to target this muscle. Exercises to help strengthen the vastus medialis include the leg press, squat, and leg extension.

Origin and insertion

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

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