The quadriceps muscle consists: the rectus femoris, the vastus medialis, the vastus lateralis and the vastus intermedius, and only the rectus femoris connects two joints: hip and knee. Muscle strain involves three degrees: minor muscle fibres disruption, tearing mostly fibers with subcutaneous haemorrhage and full tearing of the muscle. Strain patomechanism is based on near maximal muscle contraction or stretching, what occurs in repetitive sprint, jumping and kicking. This is common injury in American football, football (soccer), basketball and many others.
Also, there are other quadriceps injures (swelling, haemorrhage) , which are result of the blunt injury. This is caused by stick hitting (lacrosse, hockey) or contact with other athlete (rugby, karate).
