++
Chapter 32D. Ultrasound-Guided Obturator Nerve Block
++
++
++
Which of the following structures is most likely to remain with intact sensation following the performance of an obturator nerve block under ultrasound?
++
++
++
++
++
B. Adductor longus muscle
++
++
++
++
+
++
C is correct. During the performance of an ultrasound obturator nerve block, the articular branches are least likely to be blocked as they arise (80% of the time) from the common obturator nerve, which isn’t routinely blocked during the ultrasound guided approach.1-3
++
A, B, and D are incorrect. These choices are more reliably anesthetized using an ultrasound proximal thigh obturator nerve block.
++
++
++
Between which of the following two muscles is the posterior branch of the obturator nerve most likely to be encountered when performing an ultrasound guided obturator nerve block?
++
++
++
A. Adductor longus and pectineus
++
++
B. Adductor brevis and adductor magnus
++
++
C. Adductor longus and adductor magnus
++
++
D. Adductor brevis and pectineus
+
++
B is correct. The posterior branch lies between the fascial planes of the adductor brevis and adductor magnus muscles.4
++
A, C, and D are incorrect. These choices are unlikely to contain the posterior branch of the obturator nerve.
++
++
++
Between which of the following two muscles is the anterior branch of the obturator nerve most likely to be encountered when performing an ultrasound guided obturator nerve block?
++
++
++
A. Adductor longus and pectineus
++
++
B. Adductor brevis and adductor magnus
++
++
C. Adductor longus and adductor magnus
++
++
D. Adductor brevis and pectineus
+
++
D is correct. In the thigh, at the level of the femoral crease, the anterior branch is located between the fascia of the pectineus and adductor brevis muscles.4
++
A, B, and C are incorrect. These choices are unlikely to contain the anterior branch of the obturator nerve.
++
++
++
Under spinal anesthesia, the addition of an obturator nerve block is indicated to prevent involuntary abduction of the thigh during which of the following surgical procedures?
++
++
++
A. Transurethral resection of a lateral bladder tumor
++
++
B. Iliopsoas hematoma evacuation
++
++