|Level of blockade||Coverage distribution|
- Portion of the hip joint
- Most of the adductor muscles
- Variable portion of the medial aspect of the femur
- Inconstant skin distribution on the medial aspect of the thigh
- Branch of the lumbar plexus (L2–L4)
- Typically emerges from the medial border of the psoas muscle at the level of the pelvic brim, and divides in the obturator canal into anterior and posterior branches, although variations are common with a multiple branching pattern
- The anterior branch gives an articular branch to the hip joint, provides motor innervation of the adductor brevis, adductor longus, gracilis, and occasionally the pectineus (usually femoral nerve), and innervates a variable area of skin; most sources show an area in the medial aspect of the thigh, while others suggest a more distal location at the level of the knee. Sensory testing is thus unreliable
- The posterior branch provides motor innervation to the adductor magnus, obturator externus, and occasionally the adductor brevis (in that case, this muscle is not innervated by the anterior branch), and ends with an articular branch to the knee joint
Figure 144-1. Anatomy of the Obturator Nerve
(1) Femoral nerve; (2) obturator nerve; (3) anterior branch; (4) posterior branch; (5) adductor longus; (6) adductor brevis; (7) adductor magnus; (8) gracilis. Reproduced from Hadzic A. The New York School of Regional Anesthesia Textbook of Regional Anesthesia and Acute Pain Management. Figure 34-1. Available at: www.accessanesthesiology.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.
Figure 144-2. Sagittal Section Demonstrating the Relationship of the Obturator Nerve to the Adductor Muscles
(1) Obturator nerve passing through the obturator canal; (2) obturator externus; (3) pectineus; (4) adductor longus; (5) adductor brevis; (6) adductor magnus; (7) medial femoral condyle; (8) femoral nerve; (9) sciatic nerve. Reproduced from Hadzic A. The New York School of Regional Anesthesia Textbook of Regional Anesthesia and Acute Pain Management. Figure 34-4. Available at: www.accessanesthesiology.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.
- Supplementation of femoral and sciatic nerve blocks for lower extremity surgery, especially knee surgery
- Prevention of the obturator reflex during transurethral resection of the bladder (TURB). The reflex is due to the stimulation through the bladder of the obturator nerve, resulting in sudden thigh adduction that can cause bladder perforation. Bilateral blocks have to be performed to be effective
- Labat's original technique is uncomfortable for the patient, as it requires bone contact and multiple redirecting of the needle, and the needle may enter the pelvis if inserted too far
- The technique ...