Background and Objectives To acquire an accurate knowledge of the relationship of the sympathetic chain to the vertebral column.

Methods In dissections on 65 cadavers the authors located the sympathetic chain and its ganglia in three dimensions with respect to the vertebral column: cephalad-caudad in the sagittal plane; ventrally and laterally in the horizontal (axial) plane. The relationship of the sympathetic chain to the psoas muscle and that of the psoas muscle to the vertebral column was also established. Transparent markers were placed at each disk space and colored markers at each grossly recognizable ganglion. Photographs and measurements were then made.

Results In the sagittal plane, the lumbar ganglia were most often present opposite the middle of the body of the third vertebra and at the disks above and below. In the horizontal plane, the ganglia lay from 0 to 0.5 cm posterior to the anterior border of the third lumbar vertebra and 1.8 to 3.0 cm laterally from the center of the third lumbar vertebra. The sympathetic chain always lay anterior to the psoas muscle.

Conclusions Although the location of the ganglia is quite variable, the best approach for sympathetic block is to advance the needle paravertebrally through the fascia of the psoas muscle slightly cephalad to the midpoint of the body of L3.