The calvaria or skullcap (feminine Latin noun with plural calvariae; however many medical texts list the word as “calvarium”

The calvaria (skull cap) is made up of the superior portions of the frontal bone, occipital bone, and parietal bones.

The outer surface of the skull possesses a number of landmarks. The point at which the frontal bone and the two parietal bones meet is known as “Bregma”. The point at which the two parietal and occipital bones meet is known as “Lambda”. Not only do these landmarks indicate the fontanelle in newborns, they also act as reference points in medicine and surgery.

Intracranial pressure (ICP) is pressure inside the bony calvarium and therefore reflects the pressure of the brain parenchyma and cerebrospinal fluid (CSF). The Monro-Kellie hypothesis operates under the assumption that the cranium is incompressible and the volume inside the cranium is fixed ¹⁾.