Indications (con't)

moral nerve is the saphenous nerve, a purely sensory nerve which continues the general direction of the femoral nerve, lateral to the femoral artery in the adductor canal (Hunter's canal) accompanied by the motor branch supplying the vastus medialis muscle. Due to this close relationship, injection of local anesthetic after stimulation of the branch to the vastus medialis invariably results in saphenous nerve block. The saphenous nerve then crosses the femoral vessels anteriorly, passes behind the sartorius muscle, descends along the medial border of the tibia and divides into terminal branches at the level of the medial malleolus. The saphenous nerve supplies the skin of the medial part of the leg and foot.

Sacral plexus and sciatic nerve

The sacral plexus is formed by the union of the fifth lumbar with the first four sacral spinal nerves. It lies on the anterior aspect of the piriformis muscle, behind the posterior wall of the pelvic cavity and cannot be approached percutaneously. It supplies the posterior aspect of the upper limb and almost entire limb below the knee (except for the medial strip of skin, sup-plied by the saphenous nerve). Its two main divisions supplying the lower extremity are the posterior femoral cutaneous nerve and the sciatic nerve. The sciatic nerve is the largest mixed nerve of the body. It is formed by two distinct nerves within the same envelope, the common peroneal nerve and the tibial nerve The sciatic nerve leaves the pelvis through the greater sciatic foramen, enters the thigh between the greater trochanter of the femur and the ischial tuberosity, then runs in the subgluteal space within a "true" aponeurotic canal wherein the pressure is negative and can be detected by a loss-of-resistance technique. It is separ-ated from the hip joint by the obturator externus muscle. In the thigh, the sciatic nerve runs on the adductor magnus, along the lower border of the femur, in direction to the popliteal fos-