The Lumbar Spine (Low Back)
The area of the spine around your low back is called the lumbar spine. This area usually has 5 vertebrae. The lumbar spine connects to the sacrum, which acts as the foundation of your spine. The sacrum then, in turn, connects to your pelvis, which connects to your legs.
The bones of the lumbar spine are number L1 through L5, with the L standing for “lumbar.” Again, the discs are numbered for the two bones they are in between. For instance, the L4-5 disc is between the L4 and L5 vertebrae. Of special note in the lumber spine, the L5-S1 disc is in between the L5 vertebral body and the first bone of the sacrum (called S1).
The lumbar spine is shaped just like the cervical spine, with a lordotic curve. The vertebrae in the lumbar spine are the largest of the entire spine. The lumbar spinal canal is also larger than in the cervical or thoracic segments of the spine. The size of the lumbar spine allows for more space for nerves to move about.
When people experience pain in their spine it often occurs in the lumbar region. This is because the lumbar spine is connected to your pelvis, which is where most weight bearing and body movement takes place. Typically this is where people tend to place too much pressure, such as when lifting up a heavy box, twisting to move a heavy load, or carrying a heavy object. These activities can cause repetitive injuries that can lead to damage to the parts of the lumbar spine.