Fig. 3.

Ultrasonography and the corresponding positions of transducer. a: ultrasonography of T12 paravertebral space, when ultrasound probe was positioned as in panel d; b: ultrasonography of lumbar plexus when the ultrasound probe was positioned transversely as in panel e; c: ultrasonography of sacral plexus when ultrasound probe was positioned transversely at the level of sacral hiatus as in panel f. AP = articular process; SP = spinous process; ITL = intertransverse ligament; PV space = paravertebral space; ESM = erector spinae muscle; LP = lumbar plexus; PMm = psoas major muscle; GM = gluteus maximus muscle; sciatic n. = sciatic nerve; P = posterior; A = anterior; L = left, R = right