The sciatic nerve bifurcates into the tibial (medial) and common peroneal (lateral) nerves proximal to the popliteal crease, though there is significant anatomic variation in the location of this split. For popliteal block, inject slightly distal to the sciatic nerve bifurcation, where both the common peroneal and tibial nerves are distinctly visible in a common sheath and slightly but not widely separated. Failed or incomplete block can occur if only one nerve is blocked with injection more distal to the bifurcation. For further detail refer to UpToDate content on the popliteal block procedure.