<prompt> Locking muscle of Knee joint isVastus LateralisVastus MedialisVastus IntermediusRectus Femoris  <response>: Locking is a mechanism that allows the knee to remain in the position of full extension as in standing without much muscular effoLocking occurs as a result of medial rotation of the femur during the last stage of extension. Vastus medialis prevents lateral displacement of the patella.Reference: Chaurasia Volume II; 7th edition; Page no: 169 