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).
What Causes Pain Behind the Knee? Why Does it Hurt in the Back of my Knee or Knee Cap? Back of knee pain, also known as posterior knee pain, can come in varied forms ranging from slight to sharp pain behind knee to pain in the back of knee when bending to back of knee pain after sitting.