Laminectomy is a surgical procedure for relieving pressure on the spinal cord. The lamina is an arch of bone that forms a circle around the spinal cord. During a laminectomy, the lamina is removed or trimmed to widen the spinal canal. This creates more space for the spinal nerves.
Foraminotomy is another operation used to relieve pressure on nerves. In this case, the nerves are being compressed or pinched by the intervertebral foramina. The foramina is an opening in the bone through which the spinal nerves pass to leave the spinal cord and travel to other parts of the body.
Instead of cutting out a large segment of bone (like in the laminectomy), the opening is just made larger during a foraminotomy. This allows more space for the nerve without loss of motion or stability in the spine.
The lumbar vertebrae are much larger and stronger than the cervical bones. A laminectomy in the lumbar spine usually doesn't result in an unstable segment. Removal of the lamina in the cervical spine must be accompanied by fusion afterwards or problems can develop with instability and collapse.