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The calvaria is the top part of the skull. It is the upper part of the
neurocranium In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calvaria or skul ...
and covers the
cranial cavity The cranial cavity, also known as intracranial space, is the space within the skull that accommodates the brain. The skull minus the mandible is called the ''cranium''. The cavity is formed by eight cranial bones known as the neurocranium that i ...
containing the brain. It forms the main component of the
skull roof The skull roof, or the roofing bones of the skull, are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In comparat ...
. The calvaria is made up of the superior portions of the
frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.''Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, part ...
, occipital bone, and parietal bones. In the human skull, the
suture Suture, literally meaning "seam", may refer to: Arts, entertainment, and media * ''Suture'' (album), a 2000 album by American Industrial rock band Chemlab * ''Suture'' (film), a 1993 film directed by Scott McGehee and David Siegel * Suture (ban ...
s between the bones normally remain flexible during the first few years of postnatal development, and
fontanelle A fontanelle (or fontanel) (colloquially, soft spot) is an anatomical feature of the infant human skull comprising soft membranous gaps ( sutures) between the cranial bones that make up the calvaria of a fetus or an infant. Fontanelles allow f ...
s are palpable. Premature complete ossification of these sutures is called
craniosynostosis Craniosynostosis is a condition in which one or more of the fibrous sutures in a young infant's skull prematurely fuses by turning into bone (ossification), thereby changing the growth pattern of the skull. Because the skull cannot expand perpe ...
. In Latin, the word ''calvaria'' is used as a feminine noun with plural ''calvariae''; however, many medical texts list the word as ''calvarium'', a neuter Latin noun with plural ''calvaria''.


Structure

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 bones and the occipital bone meet is known as "Lambda". Not only do these landmarks indicate the
fontanelle A fontanelle (or fontanel) (colloquially, soft spot) is an anatomical feature of the infant human skull comprising soft membranous gaps ( sutures) between the cranial bones that make up the calvaria of a fetus or an infant. Fontanelles allow f ...
in newborns, they also act as reference points in medicine and surgery. The inner surface of the skull-cap is concave and presents depressions for the convolutions of the
cerebrum The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. I ...
, together with numerous furrows for the lodgement of branches of the meningeal vessels. Along the middle line is a longitudinal groove, narrow in front, where it commences at the frontal crest, but broader behind; it lodges the superior sagittal sinus, and its margins afford attachment to the
falx cerebri The falx cerebri (also known as the cerebral falx) is a large, crescent-shaped fold of dura mater that descends vertically into the longitudinal fissure between the cerebral hemispheres of the human brain,Saladin K. "Anatomy & Physiology: The Uni ...
. On either side of it are several depressions for the
arachnoid granulations Arachnoid granulations (also arachnoid villi, and pacchionian granulations or bodies) are small protrusions of the arachnoid mater (the thin second layer covering the brain) into the outer membrane of the dura mater (the thick outer layer). They p ...
, and at its back part, the openings of the
parietal foramina A parietal foramen is an opening in the skull for the parietal emissary vein, which drains into the superior sagittal sinus. Occasionally, a small branch of the occipital artery can also pass through it. It is located at the back part of the par ...
when these are present. It is crossed in front by the
coronal suture The coronal suture is a dense, fibrous connective tissue joint that separates the two parietal bones from the frontal bone of the skull. Structure The coronal suture lies between the paired parietal bones and the frontal bone of the skull. It ...
and behind by the lambdoid suture, while the sagittal suture lies in the medial plane between the parietal bones.


Layers

Most bones of the calvaria consist of internal and external tables or layers of compact bone, separated by
diploë Diploë ( or ) is the spongy cancellous bone separating the inner and outer layers of the cortical bone of the skull. In the cranial bones, the layers of compact cortical tissue are familiarly known as the tables of the skull; the outer one i ...
. The diploë is cancellous bone containing red bone marrow during life, through which run canals formed by
diploic vein The diploic veins are large, thin-walled valveless veins that channel in the diploë between the inner and outer layers of the cortical bone in the skull. They are lined by a single layer of endothelium supported by elastic tissue. They develop f ...
s. The diploë in a dried calvaria is not red because the protein was removed during preparation of the cranium. The internal table of bone is thinner than the external table, and in some areas there is only a thin plate of compact bone with no diploë. Calvarial bones are supplied by endosteal and periosteal sheaths which are innervated by the nociceptors, sensory, sympathetic, and parasympathetic nerves. Horizontal section of the mouse pups showed that the density of nerve fibers was highest in the region of forehead, temples, and the back of head which crossing the frontal, parietal, and interparietal bones. In the calvarial innervation in the adult mouse, CGRP-labeled fibers and peripherin were seen in the sutures, emissary canals, and bone marrow but not in diploe. Nerve fibers passing through the emissary canals and cavity of bone marrow provided the branches of periosteal and dural nerves whereas fibers from the sutures gave out to the dural nerves. File:Gray769.png File:Gray1196.png


Development

In the fetus, the formation of the calvaria involves a process known as
intramembranous ossification Intramembranous ossification is one of the two essential processes during fetal development of the gnathostome (excluding chondrichthyans such as sharks) skeletal system by which rudimentary bone tissue is created. Intramembranous ossification i ...
.


In popular culture

In many translations of the Gospels, Jesus is killed in a place named "
Calvary Calvary ( la, Calvariae or ) or Golgotha ( grc-gre, Γολγοθᾶ, ''Golgothâ'') was a site immediately outside Jerusalem's walls where Jesus was said to have been crucified according to the canonical Gospels. Since at least the early mediev ...
", a reference to this body part.


References


Further reading

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External links

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Calvaria
{{Authority control Skull la:Calvaria no:Skalletak