Dorsolateral Sacral Plexus: An Anatomical Description

Previous studies demonstrate the rich innervation of the sacroiliac joint by the sacral dorsal rami lateral branches, as well as its link to low back pain and sciatica. However, no study has detailed the terminations of the lateral branches, nor their branching structures lateral to the joint proper. In this study, we investigated the path and connectivity of the dorsal sacral rami and their relationship to the sacroiliac joint and surrounding tissues. 10 cadaveric hemipelvises were carefully dissected to reveal the path and intersections of the nerves as they exit laterally from the sacral foramina. Our dissections revealed a variable network of connectivity, from the S1 dorsal sacral rami to the S4 dorsal sacral rami, that runs laterally to the long dorsal sacroiliac ligament and terminates in a confluence of sacrococcygeal connective tissue. The dorsal rami of the posterior sacral nerve roots form a neural network consistent with a true nervous plexus; we designated the dorsolateral sacral plexus. Connecting with the coccyx, the dorsolateral sacral plexus may provide a putative neurophysiologic conduit between the lumbar spine and pelvis (notably the pelvic floor). Future studies are warranted to determine if the dorsolateral sacral plexus plays a role in lumbopelvic pain or mechanical phenomena.

Mini-abstract: The sacral dorsal rami lateral branches form a variable and complex plexus, the dorsolateral sacral plexus, which terminates in a confluence of sacrococcygeal connective tissue.

Keywords: Biomechanical phenomena; Cadaver; Humans; Sacral plexus; Sacroiliac joint