Pedal refers to the foot region, example being a pedal pulse, a pulse taken on one's foot.
Patellar refers to the patella bone also known as the kneecap, example being the patellar ligaments, the fibrous connections that link the kneecap to other bones of the lower extremity.
Popliteal refers to the posterior knee also known as the back of the knee, example being the popliteal artery, the branches of which provide blood supply to the lower extremity.
Plantar refers to the inferior portion of the foot also known as the arch of the foot, example being plantar fasciitis, a condition in which the fibrous tissue on the bottom of the foot becomes inflamed, the causes of which are still being studied.