What is ADHD? ADHD (attention deficit-hyperactivity disorder) affects both adults and school-aged children. Symptoms include restlessness, difficulty paying attention, and hyperactivity. The causes of ADHD are unknown, however factors such as diet, environment and genetics may contribute to symptoms.
The knee muscles control how the knee joint and patella move. There are two main groups of muscles, the quadriceps and the hamstrings, as well as a small muscle behind the knee (popliteus).
There are a variety of structures that surround the knee and allow it to bend and that protect the knee joint from injury. The quadriceps and hamstring muscles are responsible for moving the knee joint. When the quadriceps muscles (located on the front the thigh) contract, the knee extends or straightens.