What is a Pinched Nerve?

Many people think of a pinched nerve as that sharp discomfort in the neck or back that sometimes comes after a long day stooped in front of a computer screen, or after a long night sleeping with the head at an awkward angle on a less-than-supportive pillow. In most cases, though, this sharp pain – which can feel like someone is poking you with a meat thermometer – is nothing more than tight or strained muscles. Sometimes, the pain might be caused by a sprained ligament, as when the neck or back is jolted during a hard collision. While a muscle strain or ligament sprain might feel like a pinched nerve, the condition itself actually is much more complicated.

The Anatomy Of The Spine

An actual pinched nerve in the neck or back is exactly what it sounds like – compression, or impingement, of a spinal nerve by surrounding tissues. This can occur at any level of the spine and can cause localized pain, radiating pain, tingling, numbness, and muscle weakness, cramping, and spasms.

How does a pinched nerve happen? There are a number of potential causes, most of which involve the effect of the aging process on the spinal anatomy. Before delving into the potential causes of nerve compression, it’s important to have a basic knowledge of the spinal anatomy:

• Vertebrae – These are the bony building blocks of the spine, stacked from the neck (cervical region) to the lower back (lumbosacral region). There are a total of 33 vertebrae in the spine (seven cervical, 12 thoracic, five lumbar, five fused sacral, and four fused coccygeal). The vertebrae help keep the body upright and flexible while protecting spinal cord.

• Facet joints – Jutting off the sides of the vertebrae are joints where the vertebrae meet and move.

• Intervertebral discs – These sponge-like wedges provide cushioning between the vertebrae and serve as “springs” to allow for spinal flexibility. They are composed of a gel-like middle (nucleus pulposus) and a tough, cartilaginous outer wall (annulus fibrosus).

• Ligaments and muscles – These are connective tissues that hold everything together and support range of motion.

• The spinal cord – This long bundle of nerve tissue is part of the central nervous system and serves as a conduit between the brain and the peripheral nervous system.

• Nerve roots – At every level of the spine, nerve roots branch off the spinal cord and pass through openings in the vertebrae called foramina. These roots conduct sensory and motor signals between the peripheral nervous system and the spinal cord.

As the body ages, all of these anatomical components are subject to wear and tear. Discs lose water content and become brittle. The cartilage that lines the joints begins to deteriorate. Ligaments begin to thicken and ossify. As this happens, the structural integrity of the spine begins to break down. This places the spinal cord and nerve roots at risk for compression.

Why Does Spinal Degeneration Cause A Pinched Nerve?

Because the spinal column is such a tight fit for the spinal cord and nerve roots, any change in physical structure can produce nerve compression. Any number of age-related degenerative spine conditions could be the culprit – spinal stenosis, bulging or herniated intervertebral discs, osteoarthritis, bone spurs, and more. Nerve compression also can be caused by injury (such as a back or neck injury caused by a fall or car accident), although it is more frequently related to the natural aging process.