Neurocranium

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Neurocranium
Cranial bones en v2.svg
The eight bones that form the human neurocranium.
Neurocranium - animation02.gif
The eight cranial bones. (Facial bones are shown in transparent.)
  Yellow: Frontal bone (1)
  Blue: Parietal bone (2)
  Purple: Sphenoid bone (1)
  Orange: Temporal bone (2)
  Green: Occipital bone (1)
  Red: Ethmoid bone (1)
Details
Identifiers
Latin neurocranium
TA98 A02.1.00.007
TA2 354
FMA 53672
Anatomical terms of bone

In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan, [1] [2] is the upper and back part of the skull, which forms a protective case around the brain. [3] In the human skull, the neurocranium includes the calvaria or skullcap. The remainder of the skull is the facial skeleton.

Contents

In comparative anatomy, neurocranium is sometimes used synonymously with endocranium or chondrocranium. [4]

Structure

The neurocranium is divided into two portions:

In humans, the neurocranium is usually considered to include the following eight bones:

The ossicles (three on each side) are usually not included as bones of the neurocranium. [6] There may variably also be extra sutural bones present.

Below the neurocranium is a complex of openings (foramina) and bones, including the foramen magnum which houses the neural spine. The auditory bullae, located in the same region, aid in hearing. [7]

The size of the neurocranium is variable among mammals. The roof may contain ridges such as the temporal crests.

Development

The neurocranium arises from paraxial mesoderm. There is also some contribution of ectomesenchyme. In Chondrichthyes and other cartilaginous vertebrates this portion of the cranium does not ossify; it is not replaced via endochondral ossification.

Other animals

The neurocranium is formed by the combination of the endocranium, the lower portions of the cranial vault, and the skull roof. Through the course of evolution, the human neurocranium has expanded from comprising the back part of the mammalian skull to being also the upper part: during the evolutionary expansion of the brain, the neurocranium has overgrown the splanchnocranium. The upper-frontmost part of the cranium also houses the evolutionarily newest part of the mammal brain, the frontal lobes.

The braincase of Dilophosaurus, an extinct theropod dinosaur Dilophosaurus assigned braincase.png
The braincase of Dilophosaurus , an extinct theropod dinosaur

In other vertebrates, the foramen magnum is oriented towards the back, rather than downwards. The braincase contains a greater number of bones, most of which are endochondral rather than dermal: [8]

Additional images

See also

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References

  1. "Brainpan - Medical Definition and More from Merriam-Webster". Merriam-Webster/Medical.
  2. Nyiszli, Miklos (2011). Auschwitz: A Doctor's Eyewitness Account. New York: Arcade Publishing.
  3. 1 2 Sadler, Thomas W. (February 2009). Langman's Medical Embryology. Lippincott Williams & Wilkins. p. 173. ISBN   978-0781790697.
  4. Kent, George C.; Carr, Robert K. (2001). Comparative Anatomy of the Vertebrates (9th ed.). New York, NY: McGraw-Hill. ISBN   0-07-303869-5.
  5. In small children, the frontal bone is still separated into two parts, by the frontal suture, which normally closes during postnatal development.
  6. but if they are included, the neurocranium will then have to be said to consist of fourteen bones
  7. Elbroch, M. 2006. Animal skulls: A guide to North American species. Stackpole Books, pp. 2022. ISBN   978-0-8117-3309-0
  8. Currie, P.J. (1997). "Braincase Anatomy". In Currie, P.J.; Padian, K. (eds.). Encyclopedia of Dinosaurs. pp.  81–85. ISBN   978-0-12-226810-6.