Scanning Technique - Nerve Localization

Nerve Localization

• Take advantage of a real time anatomical examination every time a transducer is placed on the skin surface of a patient.
• Perform a complete and systematic anatomical survey in the region. This is similar to reading a chest x-ray.
• Nerves may not be readily visible at the first glance but vessels, muscles and bones are easily identifiable under ultrasound. These structures will define the target nerve location.
• It is important to visualize structures that should not be entered or trespassed (e.g., the first rib and pleura in the supraclavicular region).

Finding the Sciatic Nerve in the Popliteal Region

• First identify 1) the femur (Figure A), 2) the popliteal artery (PA, Figure B), and 3) the muscles (semitendinosus and semimembranosus ST/SM, medially and biceps femoris laterally, BF). This defines the region where the sciatic nerve will be found.
• The sciatic nerve is consistently superficial and posterior to the femur, superficial and lateral to the popliteal vessels and between the muscle layers (Figure C).
• Slightly angle the transducer towards the foot (caudad) to capture a clearer nerve image (Figure D).
• Note the hyperechoic area medial to the PA is NOT a nerve structure (arrow, Figure B).

BF = biceps femoris

Arrow = hyperechoic area   PA = popliteal artery   ST & SM = semitendinosus & semimembranosus muscles

Arrowheads = sciatic nerve   PA = popliteal artery   ST & SM = semitendinosus & semimembranosus muscles

Arrowheads = sciatic nerve   PA = popliteal artery