Healing by scar. The tissues over the area (muscle on the left and muscle on the right scar to each other, covering the dura (the sack containing the nerves or spinal cord) exposed by the laminectomy. This, and the the fat and skin over the muscle also heal. Strengthening those muscles by exercise can help recovery.
Laminectomy. A laminectomy is performed to reduce pain or nerve symptoms from neural structures that are being squeezed in a tight space. Ie the spinal canal. If you have a room filled with people and its packed, you could make more room by taking off the roof. The lamina is the "roof" to the spinal canal. So when it is removed "laminectomy" the patients complaints of leg pain , heaviness , should improve.