Femoral Nerve Block

Femoral Nerve Block – Landmarks, Technique and Videos

Femoral Nerve Blocks

Before learning Femoral Nerve Block, one has to first understand the relevant anatomy. The femoral nerve, the largest branch of the lumbar plexus, arises from the dorsal divisions of the ventral rami of the second, third, and fourth lumbar nerves (L2-L4). It descends through the fibers of the psoas major muscle, emerging from the muscle at the lower part of its lateral border, and passes down between it and the iliacus muscle, behind the iliac fascia; it then runs beneath the inguinal ligament, into the thigh, and splits into an anterior and a posterior division. Under the inguinal ligament, it is separated from the femoral artery by a portion of the psoas major.

Anatomy of Femoral Triangle

Nerve Supply Of Lower Limb

ANTERIOR APPROACH (FEMORAL NERVE BLOCK)

Patient position: Supine.

 

  • Femoral Nerve Block Landmarks
    Femoral Nerve block Landmark

Landmarks:

  • Line between ASIS and pubic tubercle (PT).
  • Parallel line at the inguinal crease.
  • 1 cm lateral to the femoral artery pulse.

Video Showing Landmark Based Nerve Stimulator Approach

Tips:

  • If the femoral artery pulse cannot be felt, the puncture point will be approximately 1 cm lateral to a point located 5 cm caudally on a perpendicular line at the midpoint of the line ASIS-PT.
  • A contraction of the vastus medialis indicates a medial and anterior approach of the nerve.
  • To obtain a contraction of the vastus intermedius (upward movement of the patella), the needle is directed posterior and laterally.
  • Single stimulation = the total dose of local anesthetic is injected when contraction of the vastus intermedius is elicited.
  • Multistimulation = injections of 5 to 7 mL local anesthetic, respectively, when a contraction of the vastus medialis, vastus intermedius, and vastus lateralis is elicited.
  • Distal pressure and large volume can procure a 3-in-1 block (the obturator nerve is missed most of the time).
  • For surgeries below the knee, a saphenous nerve block can be obtained when a vastus medialis contraction is elicited.
  • A catheter can be inserted for a continuous femoral block.

NYSORA Article on Femoral Nerve Block

Download PDF

 

NYSORA Video of USG Guided Femoral Nerve Block

SONOSITE video of USG Guided Femoral Nerve Block

 

Also read ASRA Guides for Anticoagulation before Anesthesia

ASRA Guidelines
ASRA Guidelines Anticoagulation