2A) The transverse view of the thoracic spine demonstrates the relationship of the erector spinae muscle, transverse process (TP), and ribs. Note the intercostal spinal nerve as it exits the spinal canal and gives off the ventral ramus, dorsal ramus, and sympathetic ganglion. The white arrow indicates the direction of the injection for an erector spinae plane block.

2B) The goal of the block is to place anesthetic between the erector spinae muscle and the transverse process (TP). Anesthetic is thought to flow into the paravertebral space (orange dashed circle).

Credit: Arun Nagdev