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

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

Click on the VIDEO CLIP button to view the video

– 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 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

Click on the VIDEO CLIP button to view the video

Surgery and analgesia of

– the hip joint
– the shaft of the femoral bone
– the anterior thigh
– the knee joint
– the medial leg including the medial and anterior side of the ankle joint
and the subtalar joints

The ultrasound guided femoral nerve block is a basic level block

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

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 branches of the femoral nerve innervate the anterior side of:

– the hip joint

– the femoral bone

– the knee joint including the patella

– the medial tibial epicondyle

A femoral branch to the hip joint arises from the nerve to rectus femoris

Branches to the knee joint arise from each of the nerves supplying the vastus muscles with a fourth branch from the saphenous nerve

The femoral nerve splits into the anterior and the posterior branch

The femoral nerve innervates the muscles in the anterior compartment of the thigh

The anterior branch of the femoral nerve innervates the sartorius muscle – and sometimes the pectineus muscle

The posterior femoral nerve branch innervates most of the muscles in the anterior compartment of the thigh – i.e. the quadriceps femoris (the rectus femoris and the three vastus muscles)

Before the femoral nerve emerges from under the inguinal ligament it also innervates the iliac muscle and the femoral artery

The femoral nerve runs below the iliacus fascia and on top of the iliacus muscle