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Normal Anatomy
The spinal cord and spinal nerves fit in a three dimensional box: a roof, a floor and side walls. Compromise of the three dimensional box can produce pressure on the spinal cord, the spinal nerves or both.



Central Herniated Disc
A central disc herniation (black) is located in the center of the spinal canal and can compress the spinal cord. Depending on the size of the herniation, and the degree of compression and level of location in the neck, the arms and legs may be affected. Occasionally, the function of the bowel and bladder will be disturbed. 



Posterolateral Herniated Disc
A posterolateral herniation is located to one side of the spinal canal and compresses the spinal nerve exiting to go down the arm at that level of the neck. The herniation (black) will usually effect one nerve going down the arm.



Foraminal Herniated Disc
A foraminal disc herniation (black) is located further to the side of the spinal canal underneath the nerve and is in the bony tunnel in which the nerve exits the spine. After the nerve leaves the spine, it travels into the arm to perform its intended function. Compression of the nerve in the foramen (bony tunnel) causes symptoms in one arm in the distribution of that particular nerve.



Foraminal Narrowing (Foraminal Stenosis)
Foraminal narrowing (red from above and yellow from below) is the zone in which the spinal nerve leaves the bony spinal canal to go down the arm. Compression of the nerve in the foramen (bony tunnel) causes symptoms in the arm due to compression of the nerve supplying that arm.



Uncinate Spur
Uncinate spurring (yellow) can compress the spinal nerve and produce symptoms in the arm supplied by that specific nerve. This is pressure from the floor of the spinal canal on the nerve.



Facet Spur
Facet spurring (red) can compress the spinal nerve and produce symptoms in the arm supplied by that specific nerve. This is pressure from the roof of the spinal canal on the nerve.



The natural history of the cervical herniated disc compressing the spinal nerve is controlled by essentially two factors: space available for the nerve and degree of tension on the nerve. These factors are not predictable from viewing an MRI scan.The clinical course of the patient reveals the improtance of these two factors. Why do some people with cervical nerve root compression improve without surgery? The reason is that the space available and degree of tenison factors are favorable.