Surgically freeing up the space of the spinal canal by removing a portion of the lamina (a thin, flat layer, or plate; for example, the lamina arcus vertebrae, usually just called the lamina, are plates of bone in each vertebral body).

The lamina, which is partially (or completely) removed unroofs the canal and can lead to a marked enlargement of the space available for nerves and the spinal cord. This procedure is most commonly performed in the lumbar spine (lower back).

Using a special instrument that takes little bites off bone (kerrison rongeur), the lamina of the selected level is gradually trimmed until sufficient bone is removed to free the nerves and open the canal as desired.

When this has been achieved the muscles are closed against each other by placing sutures (special threads which are knotted together). The skin is then closed and a dressing is placed.