Abstract: Objective    To investigate the positional relationship between the dorsolateral branch (DLB) of the thoracic nerve in the deep surface of the erector spinae muscle (ESM) and the paravertebral space by using cadaveric specimens, so as to provide anatomical evidence for improving ultrasound-guided erector spinae plane (ESP) block.    Methods   Eighteen embalmed and fixed adult cadaveric specimens were used. Loose tissue between the ESM-transverse process plane and the thoracic paravertebral space was removed to measure the distances between the DLB and the intertransverse ligament (ITL) and lateral costotransverse ligament (LCTL).    Results    The DLB of the thoracic nerve at the ESM-transverse process plane communicated with the spinal nerve in the paravertebral space through a bony-fibrous canal, surrounded by loose connective tissue. The distances between the DLB and ITL, and between the DLB and LCTL at the ESM-transverse process plane generally increased from T1 to T11. The smallest distances were observed at the T1 segment, which were (4.86±1.81) mm and (5.02±1.60) mm, respectively, while the largest distances were observed at the T11 segment, which were (7.94±2.43) mm and (8.43±2.57) mm, respectively.    Conclusions The DLB at the ESM-transverse process plane may be an ideal block site for ESP block. Under ultrasound guidance, using the ITL and LCTL as localization landmarks is feasible for performing ESP block.

Key words:  , Erector spinae muscle,  ,  , Plane block,  ,  , Blocking point,  ,  , Applied anatomy