THE VERTEBRAE

Posted by admin on April 1, 2009 under Healthy bones Osteoporosis Rheumatic | Be the First to Comment

No two vertebrae are identical in shape or size, but all have a roughly similar outline. Except for the first two cervical vertebrae on which the head swivels and tilts, each vertebra has a solid block called the vertebral body, facing towards the front of the trunk. The rest of the vertebra is called the neural arch, and points towards the back. The arch is made up of several bony protrusions: two struts called pedicles jut out directly from the body. From these project a pair of sideways-pointing protrusions called the transverse processes. There are two more pairs of protrusions: the superior articular processes point upwards, the inferior articular processes point downwards.

These processes have oval, smooth cartilage-covered areas, called facets, which meet the corresponding surfaces above and below to form joints, called apophyseal joints or facet joints. Each vertebra is joined to the one above and the one below: each inferior articular process forms a joint with the superior process of the vertebra below it, and so on down the line. Like many other joints in the body, these vertebral joints are enclosed in capsules lined with a moist membrane called the synovium, which is lubricated with synovial fluid.

At the back of the neural arch is a protrusion called the spinous process. The bony layers between it and the rest of the arch, one on each side, are called laminae. The spinous processes are the knobs you can feel when you run your fingers down someone’s spine.

The whole series of arches, stacked on top of each other, form a bony channel, down which passes the spinal cord, continuing from the base of the brain to the level of the first lumbar vertebra.

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