Besides the bony support offered by the skeletal system, the muscular system plays an essential role in support of the spine during both static and dynamic postures. Awareness of the principal muscles to target when training for postural support and injury prevention is key. The crucial two categories of lumbar stabilizing muscles include the primary and secondary stabilizers.
The primary stabilizers of the lumbar spine from posterior to anterior are the multifidi (MF) (Figure 17) and the transverse abdominis (TA) (Figure 18) respectively.
Figure 17. Multifidi (MF).
Figure 18. Transverse Abdominis (TA).
The MF and the TA work together providing stabilization to the spine. When the TA fires, the MF fires. The multifidi connect 1-3 vertebral bodies and function to control motion between the vertebrae such as anterior-posterior gliding of the vertebral bodies. Anteriorly, the TA wraps around the trunk and attaches to the spine via the lateral raphe or lumbar dorsal fascia. When contracted, it increases the intra-abdominal pressure causing the spine to become a more rigid structure resistant to damaging forces such as flexion, rotation, or shearing. Think of a fire hose without water running through it. The hose is supple without rigidity representing the spinal column without activation of the transverse abdominis. Now, run water through the fire hose and it becomes a rigid structure impervious to bending or twisting forces. The act of turning on the water is similar to activating the TA muscle resulting in an increase in water pressure within the hose and an increase in intra-abdominal pressure surrounding the spinal column making it also a rigid structure capable of resisting damaging forces. The combination of these two muscles form a protective corset within the body to protect the spine and hence the name, the primary stabilizers.
The secondary stabilizers are additional muscles that are important to protecting the spinal column. These are recognized as secondary stabilizers as they do not directly connect to the spinal column itself. The secondary stabilizers include the internal obliques (Figure 19), external obliques (Figure 20), gluteus maximus (Figure 21), and the gluteus medius (Figure 22). Without strong hips supporting the base of the spine, a healthy spine cannot exist. The hips should be emphasized and used in all standing or bending activities to minimize compression, shear, and rotational forces to the spine itself.
Figure 19. Internal Obliques.
Figure 21. Gluteus Maximus.
Figure 20. External Obliques.
Figure 22. Gluteus Medius.