The quadriceps muscles attach to the pelvic bone and thigh bone and then extend down to the knee cap. They form a tendon that runs a few centimetres from the bottom of the knee cap to the shin bone, and are responsible for extending the knee and performing daily activities such as stair climbing, standing movements and walking. They are also important in sporting activities that involve kicking, running and jumping. If the muscles become strained, they have generally been torn somewhere in the quadriceps. This is a common injury in sporting individuals such as those who take part in the jumping and running activities.