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#21 skull vs cranium

Cynthia Smith

The ultimate question here is are the skull and cranium really the same thing? I had a question over on the MP list. Are there differences in human/mouse terminology?

FMA and MA both consider skull synonymous with cranium; MA has cranium with synonym of skull and FMA has skull with synonym of cranium.

There is much disagreement in sources. Some define it as strictly the bones encasing the brain (excluding maxila/mandible and other facial bones), some define it as all bones except mandible and some define it as all of the bones of the head.

This is where I've looked thus far:

Wikipedia claims that cranium and the mandible are subparts of the skull, but does not cite any references.

Stedman's medical dictionary defines cranium as:
The bones of the head, collectively. In a more limited sense, the neurocranium, the bony brain containing the brain, excluding the bones of the face (viscerocrainum). SYN skull

cranium (kra´ne-әm) pl. cra´nia the large round superior part of the skull, enclosing the brain and made up of the cranial bones.

cranium n., pl., -ni·ums, or -ni·a (-nē-ə).

1. The skull of a vertebrate.
2. The portion of the skull enclosing the brain; the braincase. excludes all facial bones in the definition of cranium, i.e. neurocranium = cranium.


  • Terry Hayamizu
    Terry Hayamizu

    • assigned_to: nobody --> hayamizu
  • Terry Hayamizu
    Terry Hayamizu

    While I wouldn't consider it to be error-free, for anatomy, especially with regards to humans, most would consider Gray's Anatomy to be among the most definitive references available. Here's what it has to say about the skull and cranium:


    Cranium (see also Skull)

    (p. 271) The head is composed of the skull surrounding the brain, and an outer covering of muscles, glands and skin. The skull has two distinct portions: that surrounding the brain and special sense organs—the neurocranium—and the lower face and jaws (also the plalate, hyoid, epiglottis and larynx)—the viscerocranium.

    The neurocranium develops from the paraxial mesenchyme in the head, i.e. the first five somites and the unsegmented somitomeres rostral to the first somite, and from ectoderm via the neural crest. The basal portion of the skull is similar in structure and development to the vertebral column and is preformed in cartilage.

    The viscerocranium derives from ectoderm via invaginated head neural crest which streams into thte devleoping arches forming all the connective elements of the face. Bones of the viscerocranium form in the main from membranous ossification but there are cartilage models in each arch.

    (p. 547) Even in primitive vertebrates the neurocranium, derived from cartilages in ventral to the brain, as in human embryos, has been joined by cartilaginous supports for external nares and olfactory receptors, eyeballs and labyrinths. With the addition of jaws, of branchial origin, and dermal or ‘membrane’ bones, arising in subcutaneous mesenchyme over the head and jaws and in the buccal roof, the vertebrate skull is defined in all its complexity.

    The term cranium is sometimes reserved for the skull without its mandible but this strict usage is not adhered to here. Its upper part is a box enclosing the brain, often termed the calvaria, the remainder being the facial skeleton; its upper part is immovably fixed to the calvaria, the lower being the mobile mandible. The skull is clearly of greater practical interest, viewed as a whole, than its constituent bones.

    In the MA, "cranium" (MA:0000316; synonyms: cranial bone, skull) has part-of children including "chondrocranium" (MA:0000317; synonyms: calvarium, neurocranium) and "viscerocranium" (MA:0000318; synonym: facial bone), which I still feel is correct, It is possible, however, given the definitions given in the medical dictionaries, that "skull" might also be a synonym of neurocranium, in some contexts.

    Finally, given the existence of viscerocranium-derived structures, I would disagree that neurocranium = cranium.

  • Terry Hayamizu
    Terry Hayamizu

    • status: open --> closed