The quadriceps (or 'quads') muscle is the large muscle at the front of the thigh, and is composed of four heads.

Page updated September 2023 by Dr Sheila Strover (Clinical Editor)

quadriceps muscles


Illustration showing three of the heads of quadriceps. The fourth head - vastus intermedius - is not seen here as it lies underneath the rectus femoris.

quadriceps muscle group


Quads contraction, showing how the rectus femoris takes much of the load as the knee extends.


The quadriceps and the extensor mechanism

The quads is linked to the tibia via the patella and the patellar tendon, as well as via fibrous tissue around the patella. The whole structure moves in concert when the knee is extended - and is known as the extensor mechanism.

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Dr Sheila Strover (Editor)
BSc (Hons), MB BCh, MBA

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