Erector spinae plane infiltration and anterior rami of spinal nerve: a cadaveric study.

Background: The erector spinae plane block (ESP block) is frequently employed for thoracic, abdominal, and spinal surgeries, yet its precise mechanism of action remains a subject of debate. While initially postulated to influence both ventral and dorsal rami of the spinal nerve, recent studies indicate a predominant impact on the dorsal rami with limited involvement of the ventral rami. To elucidate this mechanism, we conducted an observational study to assess the distribution of ESP infiltration to the ventral rami.