Human leg lumbar plexus. It supplies motor innervation to iliopsoas, pectineus, sartorius, and quadriceps; and sensory branches to the anterior thigh, medial lower leg, and posterior foot. The nerves of the sacral plexus pass behind the hip joint to innervate the posterior part of the thigh, most of the lower leg, and the foot. The superior (L4-S1) and inferior gluteal nerves (L5-S2) innervate the gluteus muscles and the tensor fasciae latae. The posterior femoral cutaneous nerve (S1-S3) contributes sensory branches to the skin on the posterior thigh. The sciatic nerve (L4-S3), the largest and longest nerve in the human body, leaves the
Nerve supply to the skin the most densely innervated parts of the body. Though there is no specific categorization, both “free” nerve endings and unencapsulated nerve endings of myelinated axons are found within the dermis of those areas. The cornea, one of the other exposed mucous membranes, contains “free” nerve endings served by nonmyelinated axons. The conjunctiva contains a less dense distribution of “free” nerve endings that are served by both myelinated and unmyelinated axons. The distribution of the sensory neurons within the skin accounts for the large and overlapping receptive fields of the skin. The size of the receptive fields in turn explains why