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Level of blockadeCoverage distribution
Lumbar plexus in the psoas muscle, shortly after it exits the spine
  • Femoral nerve: quadriceps muscle, anterior aspect of thigh, medial aspect of lower leg (saphenous nerve), anterior aspect of acetabulum and femur, portion of proximal tibia
  • Lateral femoral cutaneous nerve: lateral aspect of hip and thigh
  • Obturator nerve: adductor muscles, medial femur
  • Ilioinguinal, iliohypogastric, genitofemoral: usually blocked as well
Figure 141-1. Distribution of Cutaneous Anesthesia and Analgesia from a Lumbar Plexus Block

Reproduced from Hadzic A. The New York School of Regional Anesthesia Textbook of Regional Anesthesia and Acute Pain Management. Figure 33-3. Available at: Copyright © The McGraw-Hill Companies, Inc. All rights reserved.


  • The lumbar plexus originates from L1 to L4, with often a contribution from T12. L4 gives off a branch that merges with L5 to form the lumbosacral branch, part of the sacral plexus
  • Branches of the lumbar plexus include:
    • Femoral nerve
    • Lateral femoral cutaneous nerve
    • Obturator nerve
    • Ilioinguinal, iliohypogastric, and genitofemoral nerves
  • The lumbar plexus courses through the lumbar area and the pelvis in the sheath of the psoas, and then the iliopsoas muscle (Figure 141-2)

Figure 141-2. Lumbar Plexus Anatomy

Reproduced from Morgan GE Jr, Mikhail MS, Murray MJ. Clinical Anesthesiology. 4th ed. Available at Copyright © The McGraw-Hill Companies, Inc. All rights reserved.


  • Postoperative analgesia of hip or knee surgery (associated or not to a sacral plexus block); probably no advantage over femoral nerve block for knee surgery:
    • Hip arthroscopy
    • Proximal femur ORIF
    • Hip hemiarthroplasty/THA
  • Anesthesia for lower extremity surgery, in association with a sacral plexus block
  • The block of the obturator nerve is reliable, contrary to the femoral paravascular block, and the block is more proximal, with theoretically a better coverage of the hip
  • When combined with a sciatic block, take into account total dose of local anesthetic
  • This is an advanced block and should only be performed by experienced practitioners because of potential severe complications


  • Significant coagulopathy; this is a deep block, and a psoas sheath bleeding may go unnoticed, and is not amenable to compression:
    • Single-injection or continuous psoas compartment block should be treated as neuraxial blocks with regards to coagulation issues
  • Significant lumbar spine deformity, as the position of the lumbar plexus might be distorted

Technique using NS (Figure 141-3):

  • Patient in lateral decubitus, side to be blocked up, nondependent lower extremity slightly flexed; stand behind patient
  • Draw Tuffier's line (joining the iliac crests): line A
  • Draw a line over the spinous processes (feel for the spine; the median skin fold can sag and ...

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