The vastus lateralis muscle is located on the lateral side of the thigh. This muscle is the largest of the quadriceps which includes: rectus femoris, vastus intermedius, and vastus medialis. Together, the quadriceps act on the knee and hip to promote movement as well as strength and stability. They provide power for and absorb the impact of daily activities such as walking, running, and jumping.
Upper inter-trochanteric line, base of greater trochanter, lateral linea aspera, lateral supracondylar ridge and lateral intermuscular septum
Lateral quadriceps tendon which attached onto the tibial tubercle.
Posterior division of femoral nerve (L3,4)
Lateral circumflex femoral artery
1. Extension of the knee
In everyday life, the quadriceps muscle group as a whole allows a person to stand up from sitting, walk up or down stairs along with basic walking and running. These muscles are not active while standing with knees fully extending, but become active during the heel-strike and toe-off phases of gait.
- Place palpating hand distal to greater trochanter
- Get the patient to actively and isometrically contract quadriceps
- Palpate the contracting muscle focusing on the lateral side to target vastus lateralis
- Continue to palpate distally until the quadriceps tendon
Length Tension Testing / Stretching
Stand on one leg and pull the other foot up behind your bottom
Keep your knees together and push your hips forwards to increase the stretch
Hold for between 10 and 30 seconds
Lay on your front and pull one foot up to meet your buttocks
Hold for between 10 and 30 second
Some evidence has shown that in patients with patellofemoral pain syndrome vastus lateralis contracts prematurely when compared with vastus medialis which has been hypothesised to be a cause of knee pain.  In more recent studies this theory has not been clinically proven and vastus lateralis/medialis timing has been shown to be uneven in healthy test subjects. 
- Gray HFRS, Gray's Anatomy 15th edition, New York, NY: Barnes & Noble,2010. p396-398
- Kenhub - Learn human anatomy. Functions of the vastus lateralis muscle (preview) - Human 3D Anatomy | Kenhub. Available from: https://www.youtube.com/watch?v=_9xLctoEIXs [last accessed: 28/08/2018]
- Bohm S, Marzilger R, Mersmann F, Santuz A, Arampatzis A. Operating length and velocity of human vastus lateralis muscle during walking and running. Scientific reports. 2018 Mar 22;8(1):5066.
- Cowan SM, Bennell KL, Hodges PW, Crossley KM, McConnell J. Delayed onset of electromyographic activity of vastus medialis obliquus relative to vastus lateralis in subjects with patellofemoral pain syndrome. Archives of physical medicine and rehabilitation. 2001 Feb 1;82(2):183-9.
- Chester R, Smith TO, Sweeting D, Dixon J, Wood S, Song F. The relative timing of VMO and VL in the aetiology of anterior knee pain: a systematic review and meta-analysis. BMC musculoskeletal disorders. 2008 Dec;9(1):64.