Lumbar Spinal Stenosis
Spinal stenosis occurring in the lower back is known as lumbar spinal stenosis. Because the majority of spine problems occur in the lower back, the lumbar region of the spine is the most common area for spinal stenosis diagnosis. The second most common area for spinal stenosis to occur is the cervical spine. See the next section for a brief overview of the anatomy of the spine.
Spine Anatomy
A closer look at the anatomy of the spine reveals the top part of the spine, or the neck, is known as the cervical, the middle back is called the thoracic and the lower back is referred to as the lumbar region of the spine. Each region of the spine is made up of four basic elements:
- Vertebrae
- Intervertebral discs
- The Spinal Cord
- Nerves
Lumbar Spine Anatomy
The lumbar spine region contains five vertebrae, and in medical terms these vertebrae levels are labeled: L1, L2, L3, L4, and L5. The L denotes Lumbar and the number denotes level or position on the spine.
In between each vertebrae body is a cushion known as an intervertebral disc, intervertebral discs act as shock absorbers and separators of vertebrae bodies. All vertebrae are made up of the same components (just like vertebrae from the cervical and thoracic areas), therefore lumbar vertebrae also include facet joints which link vertebrae together and enables a working movable spine. Intervertebral discs are named by the vertebrae that they separate, for example a disc that sits between the L4 and L5 vertebrae is known as L4/L5 disc, a thoracic T1/T2 (T=Thoracic) disc would be located between T1 and T2, and so forth. Finally, each level of the spine houses nerves which have a particular function for the body. Please see the nerve map below for a look at what nerve levels control which body function.
Treating Lumbar Spinal Stenosis
Depending on the severity of Lumbar Spinal Stenosis, many treatment options are available. Because spinal stenosis typically occurs over long periods of time it is treated according to its severity, health of patient and quality of life. Please review our Spinal Stenosis treatment page for more information.
Animation depicting L5/S1 Disc Protrusion
This two minute animation gives an overview of the anatomy of the spine and portrays what a disc protrusion might look like in the Lumbar region of the spine.
Spinal Nerve Map Table
The table below maps the level of the spine with nerve function(s).
| Segmental spinal Cord level and Function | |
| Level | Function |
| Cl-C6 | Neck flexors |
| Cl-T1 | Neck extensors |
| C3, C4, C5 | Supply diaphragm |
| C5, C6 | Shoulder movement, raise arm (deltoid); flexion of elbow
(biceps); C6 externally rotates the arm (supinates) |
| C6, C7, C8 | Extends elbow and wrist (triceps and wrist extensors); pronates wrist |
| C7, C8, Tl | Flexes wrist |
| C8, Tl | Supply small muscles of the hand |
| Tl -T6 | lntercostals and trunk above the waist |
| T7-Ll | Abdominal muscles |
| Ll, L2, L3, L4 | Thigh flexion |
| L2, L3, L4 | Thigh adduction |
| L4, L5, S1 | Thigh abduction |
| L5, S1 S2 | Extension of leg at the hip (gluteus maximus) |
| L2, L3, L4 | Extension of leg at the knee (quadriceps femoris) |
| L4, L5, S1, S2 | Flexion of leg at the knee (hamstrings) |
| L4, L5, S1 | Dorsiflexion of foot (tibialis anterior) |
| L4, L5, S1 | Extension of toes |
| L5, S1, S2 | Plantar flexion of foot |
| L5, S1, S2 | Nexion of toes |
Click here to download a Patient's Guide to Lumbar Spinal Stenosis, compliments of Spine University.
Last Updated: 08/10/2012