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The C5 C6 spinal motion segment is located in the lower portion of the cervical spine and consists of C5 and C6 vertebrae, and the anatomical structures connecting them. This segment helps provide neck flexibility, supports the upper cervical spine and head, and protects the spinal cord and nerve pathways.
The C5 and C6 vertebrae are connected in the back by a pair of facet joints that allow limited forward, backward and twisting motions. Articular cartilage enables the facet joints to move smoothly, while muscles, tendons, and ligaments help hold the vertebrae together. A strain or tear to any of these tissues can cause neck pain and stiffness.
Between the vertebrae is an intervertebral disc that provides flexibility and shock absorption. The disc is made up of a tough outer ring called the annulus fibrosus, which encapsulates a gel-like interior called the nucleus pulposus.
The spinal cord lies within the vertebral foramen, a space formed by the vertebral arch and vertebral body.
The C6 spinal nerve branches out from the spinal cord and exits on each side through the intervertebral foramen. It receives sensory information from skin on the thumb, inner side of the forearm, and other areas in the upper limb. The C6 nerve also has a motor component that sends signals to various muscles, such as the wrist extensors and biceps.
Spinal conditions including disc herniation or facet joint osteoarthritis may irritate the C6 nerve and cause radicular pain, tingling, numbness, and weakness along the path of the nerve. If the spinal cord is compressed at the C6 spinal level, it may cause pain and neurological deficits in the arms, legs, or anywhere below the level of compression.