The tibialis anterior is a thick and fleshy muscle that, as the name implies, sits on the front of the tibia, the main lower leg bone. It originates from the upper half of the tibia, just below the knee and tapers into a long, prominent tendon about two-thirds of the way down the leg. The long tendon goes through the ankle to insert in the bottom of the inside arch of the foot (in the tarsal bones). This muscle controls the descent of the foot during walking after the heel strikes the ground.