- Mechano-receptors = information about joint movement
- Proprio-ceptors = information about your body's position in space
- Noci-ceptors = information about noxious or pain signals.
Figure #2 is an illustr
Figure # 4 below is an illustration of the complete lumbar spine from the side, as well as the sacrum. The Sacrum is the triangular-shaped bone that the spine sits on top of. Spinal nerve roots also exit from it. Notice that the discs start at the sacrum and are present between every vertebra up the spine, except for the last two in the neck. Those two vertebral segments, named the atlas and the axis, are specialized to give you the incredible range of motion in the neck. The atlas and axis are pictured in figures
The Nerve Root arises from the spinal cord. As it exits through the intervertebral foramen, (the holes), it becomes the initial section of the spinal nerve. This nerve root is most susceptible to being compromised or irritated when there is spinal dysfunction.
The Disc is made up of two distinct parts. The Annulus Fibrosis is the tough outer 1/3 rd of the disc. It has three sets of fibers within its structure that make it strong and resistant to tearing. The fibers are orientated at 30-degree angles to one another providing additional strength. Again, notice how the body is made.3 sets of fibers at 30-degree angles, 3 points of weight-bearing on a vertebra, and the triangular shape (3 sides) of the sacrum. The triangle is one of the strongest shapes in nature and is used over and over within the anatomy of the spine. The inner portion, known as the Nucleus Pulposus is a gelatinous material that gives the disc its hydraulic properties for shock absorption and weight-bearing. When injuries occur at the disc, it is due to trauma or degeneration. Trauma usually produces tears in the annulus, which allows for the nucleus to protrude out. OUCH! Degeneration results in the annulus being worn down and away. Both mechanisms allow the spinal nerve roots to be compressed. The annulus of the disc also has a nerve supply which can generate pain by itself. Either way it happens, it's bad, and it hurts.
When these Disc injuries occur, many people call it a slipped disc. Make no mistake though, a disc cannot slip and this is incorrect terminology. A disc can tear, bulge, prolapse, protrude, extrude, fragment, degenerate, dessicate and even be sequestered, but it cannot slip!
Figure #6 is an illustration of the Atlas. The atlas is so named because of its position on the top of the vertebral column, and the fact that it supports the head. This view is from the top down. Notice how larg
Note that this is the only vertebra without a body. It truly has a unique shape for mobility. Also of great importance is how large the center hole is for the spinal column to reside. This allows for greater mobility without compromising the spinal cord. This bony ring sits upon the Axis, the second vertebra, which is so named because the atlas can freely move around it like the earth on its axis. The axis is pictured below in Figure #7.
Figure #7 illustrates the second vertebra in the spine, The Axis. The Odontoid Process or Dens, is a specialized extension of the vertebral body that is found only on the axis. It protrudes upward allowing the atlas to move around it, and attaches to the atlas by specialized ligaments known as the Alar Ligament and Accessory Ligaments. Every piece of neurological information accumulated from the body enters the spinal cord, and travels through the atlas and axis. For this reason, the magnitude of the chiropractic adjustment applied to the atlas and axis is paramount. Together the occiput, atlas, axis complex is a marvel of human developmental anatomy.
Click here to view a detailed spinal anatomy chart.