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 almost any given stimulus to the human skin can potentially activate a very large number of nerve terminals. Therefore, it is more likely that a stimulus caused by the prick of a needle be detected by more than a hundred nerve endings all sharing the same receptive field, than for that same needle prick to be detected by only one nerve ending. The different kinds of sensory stimuli that are picked up by sensory neurons are grouped into two categories: epicritic and protopathic. Epicritic neurons detect gentle touch such as caresses; light vibrations; the ability to recognize the shape of