? ??? ??? craniotomy incision of the skull (as for surgery of the brain) ??? ??? ??? diskectomy excision of an intervertebral disk (a portion of the disk is removed to relieve pressure on nerve roots) (also spelled discectomy) ??? ??? ??? laminectomy excision of a lamina (often performed to relieve pressure on the nerve roots in the lower spine caused by a herniated disk and other conditions) ???