Sulcus (neuroanatomy)

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Sulcus
Blausen 0115 BrainStructures.png
Illustration depicting general brain structures including sulci
Gyrus sulcus-en.svg
Sulcus and gyrus
Identifiers
NeuroNames 1208
TA98 A14.1.09.006
TA2 5433
FMA 75759
Anatomical terminology

In neuroanatomy, a sulcus (Latin: "furrow"; pl.: sulci) is a shallow depression or groove in the cerebral cortex. One or more sulci surround a gyrus (pl. gyri), a ridge on the surface of the cortex, creating the characteristic folded appearance of the brain in humans and most other mammals. The larger sulci are also called fissures. The cortex develops in the fetal stage of corticogenesis, preceding the cortical folding stage known as gyrification. The large fissures and main sulci are the first to develop.

Contents

Mammals that have a folded cortex are known as gyrencephalic, and the small-brained mammals that have a smooth cortex, such as rats and mice are termed lissencephalic.

Structure

Sulci in relation to circulating cerebrospinal fluid Brain and Nearby Structures.png
Sulci in relation to circulating cerebrospinal fluid

Sulci, the grooves, and gyri, the folds or ridges, make up the folded surface of the cerebral cortex. Larger or deeper sulci are also often termed fissures. The folded cortex creates a larger surface area for the brain in humans and other larger mammals, without the need of increasing the size of the skull. [1] In the human brain, two-thirds of the folded cortex is buried within the sulci, if the division of the hemispheres by the longitudinal fissure is taken into account. [2] [3]

The sulci and fissures are shallow and deep grooves respectively in the cortex. A sulcus is a shallow groove that surrounds a gyrus or part of a gyrus. A fissure is a deeper furrow that divides the brain into lobes and also into the two hemispheres as the longitudinal fissure. [4] Fissures are the most prominent and invariable of the sulci. [2]

The pia mater, the membrane surrounding the brain follows the surface of the brain into each sulcus, but the arachnoid mater stretches across all sizes of the sulci, except the longitudinal fissure where it follows the pia mater. Consequently the inner sides of almost all sulci are separated only by the pia mater and the subarachnoid space, in which the cerebrospinal fluid circulates. [5] Sulci may be considered as extensions of the subarachnoid space. [2]

The approximate depth of a sulcus ranges between one and three centimetres. Other parameters of sulcal shape are length, width, and surface area. [6] Within a sulcus there may be smaller gyri, collectively known as transverse gyri. [2]

A sulcus is not necessarily a single structure. Some sulci have one or more parts that may branch in different directions. Such parts may be short, long, isolated, or connected to other sulci. [2]

Variations

The sulcal pattern varies between human individuals, but the sulci and gyri do have a generalised arrangement, making a common nomenclature possible. [7] [2]

Types

Sulci may be described in terms of function, formation, or depth or width.[ citation needed ]

On the basis of function:

  1. A limiting sulcus separates at its floor into two areas which are different functionally and structurally e.g. central sulcus between the motor and sensory areas. [2]
  2. Axial sulcus develops in the long axis of a rapidly growing homogeneous area e.g. postcalcarine sulcus in the long axis of the striate area.
  3. Operculated sulcus separates by its lips into two areas and contains a third area in the walls of the sulcus e.g. lunate sulcus is an operculated sulcus, separating the striate and parastriate areas.

On the basis of formation:

  1. Primary sulci: formed before birth, independently. Example: central sulcus.
  2. Secondary sulcus: produced by factors other than the exuberant growth in the adjoining areas of the cortex. Examples are the lateral and parieto-occipital sulci.

On the basis of depth:

  1. Complete sulcus is very deep so as to cause elevation in the walls of the lateral ventricle. Examples are the collateral and calcarine sulci.
  2. Incomplete sulci are superficially situated and are not very deep, E.g. paracentral sulcus.
Cell mechanisms of radial glial cells, and Sonic hedgehog protein signalling promote cortical folding Early gyrification.jpg
Cell mechanisms of radial glial cells, and Sonic hedgehog protein signalling promote cortical folding

Development

The process of cortical folding is complex and incompletely understood. It is explained by a number of hypotheses including mechanical buckling, and axonal tension factors. [8] The hypotheses are not mutually exclusive and can include their combined effects, with that of another mechanism of tangential expansion. Tangential expansion is associated with radial glial cells, and a process of intercalation of cortical neurons in between cells of the outer cortical plate layer producing the outward buckling of a gyrus. [9] [10]

In humans, cerebral convolutions appear at about five months and take at least into the first year after birth to fully develop. [11] [12] [13] There is a hierarchy of morphological development with the fissures and main sulci developing ahead of others. The first sulci to develop are the primary sulci, followed by secondary sulci. The more constantly found sulci are those related to functional specialization. [2] Tertiary sulci develop primarily after birth. The development of the tertiary sulci seems to be unaffected by genetics, and more related to environmental factors. [14]

Development varies greatly between individuals. The potential influences of genetic, epigenetic and environmental factors are not fully understood. [15]

Sulci of note

Superior frontal - green;Central - red; Lateral sulcus - dark blue; Superior temporal - light blue; Intraparietal - yellow Five sulci measured.png
Superior frontal - green;Central - red; Lateral sulcus - dark blue; Superior temporal - light blue; Intraparietal - yellow
Frontal lobe

Superior frontal sulcus, Inferior frontal sulcus, Precentral sulcus, Olfactory sulcus, Orbital sulcus, Paracentral sulcus

Parietal lobe

Intraparietal sulcus, Marginal sulcus, Postcentral sulcus

Occipital lobe

Lunate sulcus, Transverse occipital sulcus, Calcarine sulcus

Temporal lobe

Superior temporal sulcus, Inferior temporal sulcus

Interlobar fissures

Longitudinal fissure, Central sulcus, Lateral sulcus, Collateral sulcus, Callosal sulcus, Parieto-occipital sulcus, Occipitotemporal sulcus, Subparietal sulcus, Cingulate sulcus

Limbic lobe

Hippocampal sulcus, Rhinal sulcus, Fimbriodentate sulcus, Central sulcus of the insula, Circular sulcus of insula

Clinical significance

The advanced cognitive abilities that have developed from the expansion of cortical folding, are shown to be adversely affected when the folds are malformed. Malformations of the cortical folds have been linked to the intellectual disabilities associated with epilepsy, schizophrenia, and autism. [16] Anomalies in gyrification can affect the width or depth of sulci that are associated with many neurological or neuropsychiatric disorders. [6] The widening of sulci is seen to indicate early atrophy in neurodegenerative disorders, and may be used as a biomarker in their progression. [6] It has been found that the width of cortical sulci increases not only with age, [17] but also with cognitive decline in the elderly. [18]

Ulegyria, is a condition of scarring in the deep regions of sulci leading to disruption of the associated gyri.

The sulci are valuable landmarks in microneurosurgery, and may also be used as corridors for surgeries. [2]

Other animals

The variation in the number 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. [11] [12] The division between the two groups occurs when cortical surface area is about 10 cm2 and the brain has a volume of 3–4 cm3. Large rodents such as beavers (40 pounds (18 kg)) and capybaras (150 pounds (68 kg)) are gyrencephalic, and smaller rodents such as rats and mice, and some New World monkeys are lissencephalic. [19] [20]

Macaque

A macaque has a more simple sulcal pattern. In a monograph Bonin and Bailey list the following as the primary sulci: [21]

Additional images

See also

Related Research Articles

<span class="mw-page-title-main">Cerebral cortex</span> Outer layer of the cerebrum of the mammalian brain

The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of neural integration in the central nervous system, and plays a key role in attention, perception, awareness, thought, memory, language, and consciousness. The cerebral cortex is the part of the brain responsible for cognition.

<span class="mw-page-title-main">Parietal lobe</span> Part of the brain responsible for sensory input and some language processing

The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.

<span class="mw-page-title-main">Frontal lobe</span> Part of the brain

The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere. It is parted from the parietal lobe by a groove between tissues called the central sulcus and from the temporal lobe by a deeper groove called the lateral sulcus. The most anterior rounded part of the frontal lobe is known as the frontal pole, one of the three poles of the cerebrum.

<span class="mw-page-title-main">Central sulcus</span> Crevice in the brain separating the frontal and parietal lobes

In neuroanatomy, the central sulcus is a sulcus, or groove, in the cerebral cortex in the brains of vertebrates. It is sometimes confused with the longitudinal fissure.

The primary sensory areas are the primary cortical regions of the five sensory systems in the brain. Except for the olfactory system, they receive sensory information from thalamic nerve projections. The term primary comes from the fact that these cortical areas are the first level in a hierarchy of sensory information processing in the brain. This should not be confused with the function of the primary motor cortex, which is the last site in the cortex for processing motor commands.

<span class="mw-page-title-main">Occipital lobe</span> Part of the brain at the back of the head

The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ob, 'behind', and caput, 'head'.

<span class="mw-page-title-main">Cerebrum</span> Large part of the brain containing the cerebral cortex

The cerebrum, telencephalon or endbrain is the largest part of the brain, containing the cerebral cortex as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. In the human brain, the cerebrum is the uppermost region of the central nervous system. The cerebrum develops prenatally from the forebrain (prosencephalon). In mammals, the dorsal telencephalon, or pallium, develops into the cerebral cortex, and the ventral telencephalon, or subpallium, becomes the basal ganglia. The cerebrum is also divided into approximately symmetric left and right cerebral hemispheres.

<span class="mw-page-title-main">Neocortex</span> Mammalian structure involved in higher-order brain functions

The neocortex, also called the neopallium, isocortex, or the six-layered cortex, is a set of layers of the mammalian cerebral cortex involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, spatial reasoning and language. The neocortex is further subdivided into the true isocortex and the proisocortex.

<span class="mw-page-title-main">Fusiform gyrus</span> Gyrus of the temporal and occipital lobes of the brain

The fusiform gyrus, also known as the lateral occipitotemporal gyrus,is part of the temporal lobe and occipital lobe in Brodmann area 37. The fusiform gyrus is located between the lingual gyrus and parahippocampal gyrus above, and the inferior temporal gyrus below. Though the functionality of the fusiform gyrus is not fully understood, it has been linked with various neural pathways related to recognition. Additionally, it has been linked to various neurological phenomena such as synesthesia, dyslexia, and prosopagnosia.

<span class="mw-page-title-main">Lateral sulcus</span> Crevice in the brain separating the frontal and parietal lobes from the temporal

The lateral sulcus is the most prominent sulcus of each cerebral hemisphere in the human brain. The lateral sulcus is a deep fissure in each hemisphere that separates the frontal and parietal lobes from the temporal lobe. The insular cortex lies deep within the lateral sulcus.

<span class="mw-page-title-main">Gyrus</span> Ridge on the cerebral cortex of the brain

In neuroanatomy, a gyrus is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci. Gyri and sulci create the folded appearance of the brain in humans and other mammals.

<span class="mw-page-title-main">Sulcus (morphology)</span> Groove in an organ surface

In biological morphology and anatomy, a sulcus is a furrow or fissure. It may be a groove, natural division, deep furrow, elongated cleft, or tear in the surface of a limb or an organ, most notably on the surface of the brain, but also in the lungs, certain muscles, as well as in bones, and elsewhere. Many sulci are the product of a surface fold or junction, such as in the gums, where they fold around the neck of the tooth.

<span class="mw-page-title-main">Lobes of the brain</span> Parts of the cerebrum

The lobes of the brain are the four major identifiable regions of the human cerebral cortex, and they comprise the surface of each hemisphere of the cerebrum. The two hemispheres are roughly symmetrical in structure, and are connected by the corpus callosum. Some sources include the insula and limbic lobe but the limbic lobe incorporates parts of the other lobes. The lobes are large areas that are anatomically distinguishable, and are also functionally distinct. Each lobe of the brain has numerous ridges, or gyri, and furrows, sulci that constitute further subzones of the cortex. The expression "lobes of the brain" usually refers only to those of the cerebrum, not to the distinct areas of the cerebellum.

<span class="mw-page-title-main">Posterior cerebral artery</span> Artery which supplies blood to the occipital lobe of the brain

The posterior cerebral artery (PCA) is one of a pair of cerebral arteries that supply oxygenated blood to the occipital lobe, part of the back of the human brain. The two arteries originate from the distal end of the basilar artery, where it bifurcates into the left and right posterior cerebral arteries. These anastomose with the middle cerebral arteries and internal carotid arteries via the posterior communicating arteries.

<span class="mw-page-title-main">Inferior temporal gyrus</span> One of three gyri of the temporal lobe of the brain

The inferior temporal gyrus is one of three gyri of the temporal lobe and is located below the middle temporal gyrus, connected behind with the inferior occipital gyrus; it also extends around the infero-lateral border on to the inferior surface of the temporal lobe, where it is limited by the inferior sulcus. This region is one of the higher levels of the ventral stream of visual processing, associated with the representation of objects, places, faces, and colors. It may also be involved in face perception, and in the recognition of numbers and words.

<span class="mw-page-title-main">Parieto-occipital sulcus</span> Fold which separates the parietal and occipital lobes of the brain

In neuroanatomy, the parieto-occipital sulcus is a deep sulcus in the cerebral cortex that marks the boundary between the cuneus and precuneus, and also between the parietal and occipital lobes. Only a small part can be seen on the lateral surface of the hemisphere, its chief part being on the medial surface.

<span class="mw-page-title-main">Calcarine sulcus</span> Anatomical landmark in the brain of humans and other primates

The calcarine sulcus is an anatomical landmark located at the caudal end of the medial surface of the brain of humans and other primates. Its name comes from the Latin "calcar" meaning "spur". It is very deep, and known as a complete sulcus.

Gyrification is the process of forming the characteristic folds of the cerebral cortex. The peak of such a fold is called a gyrus, and its trough is called a sulcus. The neurons of the cerebral cortex reside in a thin layer of gray matter, only 2–4 mm thick, at the surface of the brain. Much of the interior volume is occupied by white matter, which consists of long axonal projections to and from the cortical neurons residing near the surface. Gyrification allows a larger cortical surface area, and hence greater cognitive functionality to fit inside a smaller cranium.

<span class="mw-page-title-main">Lunate sulcus</span>

In brain anatomy, the lunate sulcus or simian sulcus, also known as the sulcus lunatus, is a fissure in the occipital lobe variably found in humans and more often larger when present in apes and monkeys. The lunate sulcus marks the transition between V1 and V2, the primary and secondary visual cortices.

<span class="mw-page-title-main">Occipital gyri</span> Three parallel gyri of the occipital lobe of the brain

The occipital gyri (OcG) are three gyri in parallel, along the lateral portion of the occipital lobe, also referred to as a composite structure in the brain. The gyri are the superior occipital gyrus, the middle occipital gyrus, and the inferior occipital gyrus, and these are also known as the occipital face area. The superior and inferior occipital sulci separates the three occipital gyri.

References

  1. ↑ Cusack, Rhodri (1 April 2005). "The Intraparietal Sulcus and Perceptual Organization". Journal of Cognitive Neuroscience. 17 (4): 641–651. doi:10.1162/0898929053467541. PMID   15829084.
  2. 1 2 3 4 5 6 7 8 9 Ribas, Guilherme Carvalhal (February 2010). "The cerebral sulci and gyri". Neurosurgical Focus. 28 (2): E2. doi: 10.3171/2009.11.focus09245 . PMID   20121437.
  3. ↑ Willbrand, Ethan H.; Maboudian, Samira A.; Kelly, Joseph P.; Parker, Benjamin J.; Foster, Brett L.; Weiner, Kevin S. (1 June 2023). "Sulcal morphology of posteromedial cortex substantially differs between humans and chimpanzees". Communications Biology. 6 (1): 586. doi:10.1038/s42003-023-04953-5. PMC   10235074 . PMID   37264068.
  4. ↑ Carlson, N. R. (2013). Physiology of Behavior. Upper Saddle River, NJ: Pearson Education Inc.
  5. ↑ Brodal, Per (2004). The Central Nervous System: Structure and Function. New York: Oxford University Press. p. 89. ISBN   978-0-19-516560-9.
  6. 1 2 3 Sun, BB; Loomis, SJ; Pizzagalli, F; et al. (14 October 2022). "Genetic map of regional sulcal morphology in the human brain from UK biobank data". Nature Communications. 13 (1): 6071. Bibcode:2022NatCo..13.6071S. doi:10.1038/s41467-022-33829-1. PMC   9568560 . PMID   36241887.
  7. ↑ Ono, Michio; Kubik, Stefan; Abernathey, Chad D. (1990). Atlas of the cerebral sulci. Stuttgart: Georg Thieme Verlag. ISBN   0-86577-362-9.
  8. ↑ Andrews, TGR; Priya, R (17 June 2024). "The Mechanics of Building Functional Organs". Cold Spring Harbor Perspectives in Biology: a041520. doi:10.1101/cshperspect.a041520. PMC   7616527 . PMID   38886066.
  9. ↑ Striedter, Georg F.; Srinivasan, Shyam; Monuki, Edwin S. (8 July 2015). "Cortical Folding: When, Where, How, and Why?". Annual Review of Neuroscience. 38 (1): 291–307. doi:10.1146/annurev-neuro-071714-034128. PMID   25897870.
  10. ↑ Ronan, L; Voets, N; Rua, C; et al. (August 2014). "Differential tangential expansion as a mechanism for cortical gyrification". Cerebral Cortex. 24 (8): 2219–28. doi:10.1093/cercor/bht082. PMC   4089386 . PMID   23542881.
  11. 1 2 Hofman, MA (1985). "Size and shape of the cerebral cortex in mammals. I. The cortical surface". Brain, Behavior and Evolution. 27 (1): 28–40. doi:10.1159/000118718. PMID   3836731.
  12. 1 2 Hofman, M. A. (1989). "On the evolution and geometry of the brain in mammals". Progress in Neurobiology. 32 (2): 137–158. doi:10.1016/0301-0082(89)90013-0. PMID   2645619.
  13. ↑ Richman, D. P.; Stewart, R. M.; Hutchinson, J. W.; Caviness Jr, V. S. (1975). "Mechanical model of brain convolutional development". Science. 189 (4196): 18–21. doi:10.1126/science.1135626. PMID   1135626.
  14. ↑ White, T; Su, S; Schmidt, M; Kao, CY; Sapiro, G (February 2010). "The development of gyrification in childhood and adolescence". Brain and cognition. 72 (1): 36–45. doi:10.1016/j.bandc.2009.10.009. PMID   19942335.
  15. ↑ Dubois, J.; Benders, M.; Cachia, A.; Lazeyras, F.; Ha-Vinh Leuchter, R.; Sizonenko, S. V.; Borradori-Tolsa, C.; Mangin, J. F.; Huppi, P. S. (2008). "Mapping the Early Cortical Folding Process in the Preterm Newborn Brain". Cerebral Cortex. 18 (6): 1444–1454. doi:10.1093/cercor/bhm180. PMID   17934189.
  16. ↑ Akula, SK; Exposito-Alonso, D; Walsh, CA (18 December 2023). "Shaping the brain: The emergence of cortical structure and folding". Developmental Cell. 58 (24): 2836–2849. doi:10.1016/j.devcel.2023.11.004. PMC   10793202 . PMID   38113850.
  17. ↑ Liu, T; Wen, W; Zhu, W; et al. (15 May 2010). "The effects of age and sex on cortical sulci in the elderly". NeuroImage. 51 (1): 19–27. doi:10.1016/j.neuroimage.2010.02.016. PMID   20156569.
  18. ↑ Liu, T.; Wen, W.; Zhu, W.; Kochan, N. A.; Trollor, J. N.; Reppermund, S.; Jin, J. S.; Luo, S.; Brodaty, H.; Sachdev, P. S. (2011). "The relationship between cortical sulcal variability and cognitive performance in the elderly". NeuroImage. 56 (3): 865–873. doi:10.1016/j.neuroimage.2011.03.015. PMID   21397704.
  19. ↑ 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)
  20. ↑ Garcia, KE; Kroenke, CD; Bayly, PV (24 September 2018). "Mechanics of cortical folding: stress, growth and stability". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 373 (1759). doi:10.1098/rstb.2017.0321. PMC   6158197 . PMID   30249772.
  21. ↑ Gerhardt von Bonin, Percival Bailey, The Neocortex of Macaca Mulatta, The University of Illinois Press, Urbana, Illinois, 1947
  22. ↑ Ten Donkelaar, HJ; Tzourio-Mazoyer, N; Mai, JK (2018). "Toward a Common Terminology for the Gyri and Sulci of the Human Cerebral Cortex". Frontiers in Neuroanatomy. 12: 93. doi: 10.3389/fnana.2018.00093 . PMC   6252390 . PMID   30510504.
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