In neuroanatomy, a sulcus (Latin: "furrow", pl. sulci) is a depression or fissure in the surface of the brain. It surrounds the gyri, creating the characteristic appearance of the brain in humans and other large mammals.
Large furrows (sulci) that divide the brain into lobes are often called fissures. The large furrow that divides the two hemispheres - the interhemispheric fissure - is very rarely called a "sulcus".
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Individual variation
The sulcal pattern varies between human individuals, and the most elaborate overview on this variation is probably an atlas by Ono, Kubick and Abernathey: Atlas of the Cerebral Sulci[1]. Some of the larger sulci are, however, seen across individuals - and even species - so it is possible to establish a nomenclature.
Gyrification across species
The variation in the amount of fissures in the brain (gyrification) between species is related to the size of the animal and the size of the brain. Mammals that have smooth-surfaced or nonconvoluted brains are called lissencephalics and those that have folded or convoluted brains gyrencephalics.[2][3] The division between the two groups occurs when cortical surface area is about 10 cm2 and the brain as a volume of 3-4 cm3. Large rodents such as beavers (40 pounds) and capybaras (150 pounds) are gyrencephalic and smaller rodents such as rats and mice lissencephalic[4].
Brain development
In humans, cerebral convolutions appear at about 5 months and take at least into the first year after birth to fully develop.[5][2][3]
Notable sulci
- Lateral sulcus, lat. sulcus lateralis with 3 branches: ramus ascendens, ramus anterior, and ramus posterior
- Central sulcus, lat. sulcus centralis
- Postcentral sulcus, lat. sulcus postcentralis
- Precentral sulcus, lat. sulcus praecentralis
- Cingulate sulcus, lat. sulcus cinguli
Subcallosal sulcus, lat. sulcus corporis callosi
- Superior frontal sulcus, lat. sulcus frontalis superior
- Inferior frontal sulcus, lat. sulcus frontalis inferior
Superior temporal sulcus, lat. sulcus temporalis superior
Inferior temporal sulcus, lat. sulcus temporalis inferior
Parieto-occipital sulcus, lat. sulcus parietoocipitalis
Intraparietal sulcus, lat. sulcus intraparietalis
Collateral sulcus, lat. sulcus collateralis
Calcarine sulcus, lat. sulcus calcarinus
Macaque
A macaque has a more simple sulcal pattern. In a monograph Bonin and Bailey list the following as the primary sulci[6]:
- Calcarine fissure (ca)
- Central sulcus (ce)
- Sulcus cinguli (ci)
- Hippocampal fissure (h)
- Sulcus intraparitalis (ip)
- Lateral fissure (or Sylvian fissure) (la)
- Sulcus olfactorius (olf)
- Medial parieto-occipital fissure (pom)
- fissura rhinalis (rh)
- Sulcus temporalis superior (ts) - this sulcus runs parallel to the lateral fissure and extends to the temporal pole and often superficially merges with it.
See also
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References
- ^ Ono, Kubick, Abernathey, Atlas of the Cerebral Sulci, Thieme Medical Publishers, 1990. ISBN 0-86577-362-9. ISBN 3-13-732101-8.
- ^ a b Hofman MA. (1985). Size and shape of the cerebral cortex in mammals. I. The cortical surface. Brain Behav Evol. 27(1):28-40. PMID 3836731
- ^ a b Hofman MA. (1989).On the evolution and geometry of the brain in mammals. Prog Neurobiol.32(2):137-58. PMID 2645619
- ^ Martin I. Sereno, Roger B. H. Tootell, "From Monkeys to humans: what do we now know about brain homologies," Current Opinion in Neurobiology 15:135-144, (2005).
- ^ Caviness VS Jr. (1975). Mechanical model of brain convolutional development. Science. 189(4196):18-21. PMID 1135626
- ^ Gerhardt von Bonin, Percival Bailey, The Neocortex of Macaca Mulatta, The University of Illinois Press, Urbana, Illinois, 1947
External links
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