https://mayfieldclinic.com/pe-craniotomy.htm

CraniotomyOpen print version
Overview

Craniotomy is a surgery to cut a bony opening in the skull. A section of the skull, called a bone flap, is removed to access the brain underneath. A craniotomy may be small or large depending on the problem. It may be performed to treat brain tumors, hematomas (blood clots), aneurysms or AVMs, traumatic head injury, foreign objects (bullets), swelling of the brain, or infection. The bone flap is usually replaced at the end of the procedure with tiny plates and screws.
What is a craniotomy?

Craniotomies are named according to the area of skull (cranium) to be removed (Fig. 1). After the surgeon repairs the problem, the bone flap is then replaced or covered with plates and screws. If the bone flap is not replaced, the procedure is called a craniectomy.