Cranium
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This page is part of the EvoWiki Encyclopedia of Anatomy and Physiology. |
Found in craniates, the cranium refers to the entire skull bone structure, excluding the mandible (lower jaw).
Contents |
Morphology
The bones of the tetrapod cranium can be divided into two main elements: The neurocranium and the splanchocranium.
Sutures are where bones meet each other and they fuse during physical development, a feature far more common in mammals, where some bones are fused so completely that they appear to be a single bone. Indicated below are the compound bones of mammals, with the components (homologous to the bones of diapsids) listed as indented.
Neurocranial bones
The neurocranium are the bone elements of the braincase (neurocranium).
- Frontal bone
- Prefrontal
- Post frontal
- Parietal bones
- Temporal bone
- Tabular
- Supratemporal
- Intertemporal
- Quadrate
- Squamosal (sometimes considered a seperate bone in lower mammals)
- Occipital bone
- Supraoccipital
- Exoccipitals
- Basioccipital
- Interparietal (sometimes considered a seperate bone in lower mammals)
- Sphenoid bone (may not fuse in all mammals)
- Epiptrygoid (Alisphenoid in mammals)
- Basisphenoid
- Presphenoid
Splanchocranial bones
The splanchocranium is comprised of the bones of the face, and roof of the mouth (palate):
- Premaxilla (called "Incisive" in most mammals) - makes up most of the beak of birds
- Maxilla (fuses with its pair and the premaxillary pair in some mammals, forming a single bone)
- Nasal pair of bones.
- Vomer bone
- Zygomatic (or "Jugal" in non-mammals) pair of bones
- Quadratojugal
- Lacrimal pair of bones
References
- Liem K.F, Bemis W.E, Walker W.F Jr, and Grande L. (2001), "Functional anatomy of the vertebrates : an evolutionary perspective", Harcourt College Publishers, Third Edition, pp233-67
