The tibial and common fibular nerves originate proximal to the popliteal fossa as the two major branches of the sciatic nerve. They are the most superficial of the neurovascular structures in the popliteal fossa and enter the region directly from above under the margin of the biceps femoris muscle:
The tibial nerve descends vertically through the popliteal fossa and exits deep to the margin of the plantaris muscle to enter the posterior compartment of the leg.