Anatomy and computed tomography of the normal lumbosacral plexus.

The main nerves of the pelvis and lower limbs arise from the lumbar and sacral plexuses. These nerves can be affected by any of a large number of pathologic processes that occur in the paravertebral and pelvic regions. Understanding of the neurological findings related to paravertebral and pelvic pathology needs complete and accurate knowledge of the anatomy of these regions. The axial transverse sections of computed tomography give perfect visualisation of the anatomy of osseous, muscular, and vascular structures of the vertebral and paravertebral area and pelvic walls. Visualisation of the nerves in this regions is much more difficult, because direct demonstration of nervous structures by computed tomography is usually impossible. To be able to identify components of the lumbosacral plexus on axial CT sections the radiologist has to know the location of the nervous structures and the relationships of these structures to vascular, muscular and osseous structures which are easily demonstrated.