Imaging the L5-S1 Joint Space

摘要

The lumbar spine comprises the largest vertebral bodies in the spinal column. These vertebrae are located below the thoracic vertebrae and continue down to the sacrum. Most patients have a total of 5 lumbar vertebrae that are named according to their order in the vertebral column.1 For example, the fifth lumbar vertebra, which is closest to the sacral body, is named L5; the next vertebra up the spinal column is L4 and so on. Each vertebra is a complex body that consists of various parts (see Figure I).1 The sacrum is situated in the posterior part of the pelvic opening at the base of the spine. The sacrum is made up of 5 fused portions.1 They also are referred to often as numbered segments, with the segment closest to the lumbar spine labeled SI. An intricate arrangement of nerves protrudes from the lumbar vertebrae, and a disk fills the spaces between each vertebra and between the last lumbar vertebra and the sacrum. These disks are composedof a cartilaginous material that allows for movement of the spine.