The lower extremity sensation is provided mainly by two major nerves: the sciatic (posterior) and femoral (anterior) nerves.
The lumbar plexus consists of the ventral rami of L1-L4 with occasional contribution from T12. The lumbar plexus forms the lateral femoral cutaneous (L2-L3) which innervates the lateral thigh, femoral (L2-L4) innervating the anteromedial thigh and anteromedial lower leg/medial ankle/foot via saphenous nerve, and obturator nerve (L2-L4) which innervates the distal third of the medial thigh.
The lumbosacral plexus (L4-L5/S1-S3) forms the sciatic nerve. The posterior cutaneous nerve of thigh (S1-S3) provides sensory innervation to the inferior buttocks and posterior thigh. It follows the course of the sciatic nerve. The sciatic nerve branches, just proximal to the popliteal fossa, giving rise to the common fibular (peroneal) and tibial nerves. The common fibular nerve provides sensory innervation to the posterolateral lower leg and dorsum of the foot. The common fibular nerve branches into the deep fibular and superficial fibular nerves. The superficial fibular provides sensation to the dorsum of the foot except for the region between the 1st and 2nd digits which is provided by the deep fibular nerve. The tibial nerve provides sensory innervation to the heel and sole of the foot. The sural nerve (S1-S2) provides sensation for the posterolateral lower leg including the lateral margin of the foot to the 5th digit.