The saphenous nerve is the biggest branch from the femoral nerve

The saphenous nerve runs in the thigh in the femoral triangle and the adductor canal alongside the femoral vessels. In the femoral triangle and the upper part of the adductor canal the saphenous nerve is lateral to the vessels

The saphenous nerve is 100% sensitive innervating the medial part of the knee capsule, the skin and subcutaneous tissue antero-inferior to the knee, of the medial leg, the medial ankle joint and the subtalar joints

Indications: For surgical anaesthesia or pain management of the leg you should combine a sciatic and a saphenous nerve block

In the femoral triangle and the adductor canal the femoral artery is located under the triangular sartorius muscle (SM)

The saphenous nerve (SN) is sandwiched between the femoral artery (FA), the SM and the medial vastus muscle (MVM) in the femoral triangle and the proximal end of the adductor canal (AC). In the distal end of the canal the nerve is usually medial to the artery

Use in-plane (IP) approach from the lateral end of the transducer in the midthigh midways between the anterior superior iliac spine and the base of patella which is inside the femoral triangle

Complete perineural spread of local anaesthetic usually requires only a few milliliters of local anaesthetic and the duration of anaesthesia is oftentimes very prolonged – often more than 15 hours with ropivacaine

The saphenous nerve is a branch of the posterior branch of the femoral nerve

The saphenous nerve innervates the antero-medial part of the knee and the leg including the medial malleolus and and the anterior side of the ankle joint and the subtalar joints

Position: place the patient supine, rotate the thigh external

Probe: select a linear, high-frequency transducer

Place/Plane: place the transducer mid-thigh medially and perpendicular to the adductor canal

First locate the pulsatile femoral artery

You may track the artery from the inguinal ligament until it dives under the sartorius muscle

Local anaesthetic is injected just lateral to the femoral artery in the triangular space between the femoral artery, the sartorius muscle and the medial vastus muscle

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– Place a linear high-frequency probe in the inguinal groove and identify the pulsatile femoral artery
– Align the artery to the centre of the monitor by adjusting the position of the probe and the depth of the image
– Locate the femoral nerve (FN) lateral to the artery on top of the iliac muscle. The FN is usually flattened, spindle-shaped or triangular – rarely round
– Capture the best possible cross-sectional image of the FN by tilting the probe 10-30 degrees cranially
– Insert the needle from the lateral end of the probe
– Advance the needle inside the plane of the ultrasound beam (in-plane, IP) until the tip of the needle touches the deep surface of the FN tangentially
– The endpoint is complete perineural spread of local anaesthetic

The hyperechoic femoral nerve is usually spindle-shaped or oval

It can sometimes be triangular but is rarely round

Injection of local anaesthetic enhances the visibility of the nerve

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The advantage of the in-plane approach to block the femoral nerve is that the target nerve and the needle tip and the spread of the injected local anaesthetic can be observed simultaneously

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The anterior branch of the femoral nerve gives off the intermediate and the medial cutaneous nerves of the thigh

– the intermediate cutaneous nerve of the thigh innervates the skin of the
anterior thigh

– the medial cutaneous nerve of the thigh innervates the skin of the medial
thigh and knee

The posterior branch of the femoral nerve gives off the saphenous nerve, which is a sensory nerve innervating the antero-medial parts of the knee and the leg – sometimes as far distal as the big toe

The saphenous nerve is a branch of the posterior branch of the femoral nerve

The saphenous nerve innervates the antero-medial part of the knee and the leg including the medial malleolus and the subtalar joints

The saphenous nerve can be blocked individually in the adductor canal in the medial part of the upper thigh