Toward a Common Terminology for the Gyri and Sulci of the Human Cerebral Cortex

The gyri and sulci of the human brain were defined by pioneers such as Louis-Pierre Gratiolet and Alexander Ecker, and extensified by, among others, Dejerine (1895) and von Economo and Koskinas (1925). Extensive discussions of the cerebral sulci and their variations were presented by Ono et al. (1990), Duvernoy (1992), Tamraz and Comair (2000), and Rhoton (2007). An anatomical parcellation of the spatially normalized single high resolution T1 volume provided by the Montreal Neurological Institute (MNI; Collins, 1994; Collins et al., 1998) was used for the macroscopical labeling of functional studies (Tzourio-Mazoyer et al., 2002; Rolls et al., 2015). In the standard atlas of the human brain by Mai et al. (2016), the terminology from Mai and Paxinos (2012) is used. It contains an extensively analyzed individual brain hemisphere in the MNI-space. A recent revision of the terminology on the central nervous system in the Terminologia Anatomica (TA, 1998) was made by the Working Group Neuroanatomy of the Federative International Programme for Anatomical Terminology (FIPAT) of the International Federation of Associations of Anatomists (IFAA), and posted online as the Terminologia Neuroanatomica (TNA, 2017: http://FIPAT.library.dal.ca) as the official FIPAT terminology. This review deals with the various terminologies for the cerebral gyri and sulci, aiming for a common terminology.

Recently, a revision of the terminology on the central nervous system in the Terminologia Anatomica (TA, 1998) was made by the Working Group Neuroanatomy of the Federative International Programme for Anatomical Terminology (FIPAT) of the International Federation of Associations of Anatomists (IFAA), and posted online as the Terminologia Neuroanatomica (TNA, 2017: http://FIPAT.library.dal.ca; for an introductory paper, see ten Donkelaar et al., 2017) as the official FIPAT terminology. This review deals with the various terminologies for the cerebral gyri and sulci on the superolateral, inferomedial, and basal surfaces of the cerebrum, aiming for a common terminology. It combines the data from the TNA (2017), an illustrated version (ten Donkelaar et al., 2018) and additional terms found in preparing this review.

BRIEF REVIEW OF THE LITERATURE
In Figure 1, the wealth of gyri and sulci of the human cerebral cortex as distinguished by von Economo and Koskinas (1925) is shown. The gyri of the cerebral lobes are indicated by the classical numbering such as F1-F3, T1-T4, and the sulci without capitals (f1, f2, etc). Clearly visible are the first and second intermediate parietal sulci of Jensen and Eberstaller (s.imdI and s.imdII, respectively) as well as the frontomarginal sulcus of Wernicke with various components. Many of the smaller or infrequent sulci were forgotten, several of which were reintroduced in the recent human brain mapping era and in the TNA. The Supplementary Table 1 contains a list of synonyms and eponyms for the cerebral gyri and the Supplementary Table 2 those of the main sulci.
In the atlas of Mai et al. (2016) and the recent pocket atlas by Mai and Majtanik (2017), the use of the term fissure is advocated for the lateral, parietooccipital and hippocampal sulci. In the BNA (1895), the terms fissurae cerebri lateralis, collateralis, parietooccipitalis, calcarina, and hippocampi were used. In the JNA (1936), only the lateral, Sylvian fissure remained as fissure. This was corrected in the PNA (1955) and later editions, and for the cerebrum, the term fissure is in use only for the interhemispheric fissure. Therefore, the term fissure should not have been advocated anymore.
Minor differences in Mai et al. (2016) Zlatkina and Petrides, 2014), medial occipitotemporal gyrus as a common term for the lingual gyrus and the parahippocampal gyrus, periinsular sulcus for the circular sulcus of the insula, and a rather extensive terminology for the opercula, including frontal, frontoparietal, and temporal opercula (Figure 3). Their frontoparietal operculum includes the anterior central (precentral) operculum, the subcentral gyrus, the posterior central (postcentral) operculum, and the parietal operculum. The first three collectively may belong to the subcentral gyrus.
In their atlas of the human brain in MNI space, Mai et al. (2016) presented photographs of cell-stained sections of the right hemisphere of a 24-year-old male from the Vogtcollection in Düsseldorf (Vogt and Vogt, 1919). Schematic drawings show delineations of the cortex, which are based on the original maps of Brodmann (1909). The surfacebased maps by Van Essen (2005); Van Essen et al. (2012) were modified by manually estimating areal boundaries on the atlas drawing and transforming them on the surface of the 3D reconstruction. Nieuwenhuys et al. (2015) adapted the standard brain, generated from the colin27 brain (http:// www.bic.mni.mcgill.ca/ServicesAtlases/Colin27). In Figures 4, 5, gyri and sulci are shown for the lateral and medial aspects, respectively. The colin27 image is the result of averaging 27 linearly registered high-resolution T1-weighted scans of the same individual (Collins, 1994;Collins et al., 1998;Holmes et al., 1998), matched to the MNI305-space (Mazziota et al., 2001). Several neuroimaging software systems adopted the colin27 template as the standard reference. Nieuwenhuys et al. (2015) noted a few peculiarities of the colin27 template brain: (1) the Broca area of the inferior frontal gyrus is very large, but the middle frontal gyrus is relatively narrow; (2) the superior temporal sulcus is not continuous with the groove marking the cortex of the angular gyrus; (3) both the collateral and cingulate sulci are interrupted, and the posterior part of the cingulate sulcus shows an unusual zigzag course; and (4) the upper surface of the splenium of the corpus callosum has a remarkable bump. It may be added that no attempt was made to subdivide the lateral aspect of the occipital lobe, and that the fairly constant frontomarginal sulcus is absent.
In this review, the terminology of the recent TNA (2017) is presented along with short descriptions and currently used synonyms, and summarized in Tables 1-3. Both English and Latin official terms from the TNA are used. The sulci of the cerebral cortex can be divided into interlobar sulci, separating the cerebral lobes, and lobar sulci present in a lobe.
The frontal lobe (lobus frontalis) shows the following gyri: the superior, middle and inferior frontal gyri (gyrus frontalis superior, -medius, and -inferior), classically numbered F1, F2, and F3, separated by superior and inferior frontal sulci (sulcus frontalis superior and-inferior, classically numbered f1 and f2, see Figure 1), and the precentral gyrus (gyrus precentralis). The central sulcus usually does not reach the lateral sulcus, and is separated from it by a short gyrus, the subcentral gyrus (gyrus subcentralis), delimited in front and behind by the anterior and posterior subcentral sulci (sulcus subcentralis anterior andposterior), respectively, as distinguished by Dejerine (1895); Testut and Latarjet (1948). The subcentral gyrus is also known as the central or Rolandic operculum. The inferior frontal gyrus comprises three parts, orbital, triangular and opercular (pars orbitalis, pars triangularis and pars opercularis). The opercular part forms the frontal operculum. Occasionally, the diagonal sulcus (sulcus diagonalis of Eberstaller) can divide the opercular part of the inferior frontal gyrus into two parts. The triangular part may also be indented from above by a radiate sulcus (sulcus radiatus of Eberstaller). The orbital part is continuous with the basal surface of the frontal lobe, where it merges with the lateral orbital gyrus. The triangular and opercular parts form together the motor language area of Broca (1863); Amunts et al. (1999); Amunts and Zilles (2012). Recent mapping approaches based on cytoarchitecture, transmitter receptor distribution and connectivity revealed a highly differentiated segregation of this region . The frontomarginal sulcus (sulcus frontomarginalis of Wernicke) is fairly constant, found at the frontal pole, and connected posteriorly with the middle frontal sulcus. It has two branches, one deep medial branch that borders the frontopolar gyri, and a shallow lateral branch that separates the frontomarginal sulcus from the medial frontal gyrus and the orbital part of the inferior frontal gyrus, respectively. The frontopolar area (area frontopolaris) at the frontal pole (polus frontalis) shows three frontopolar gyri, superior, middle, and inferior, that are clearly separated by limiting sulci, interposed between the superior frontal gyrus and the frontomarginal gyrus. Bludau et al. (2014) distinguished two cytoarchitectonically and functionally distinct areas: the lateral frontopolar area 1 (Fp1) and the medial frontopolar area 2 (Fp2).
On the upper surface of the superior temporal gyrus (Figure 7), forming the temporal operculum, the planum polare, the anterior and posterior transverse gyri (gyrus temporalis transversus anterior and -posterior of Heschl) and the planum temporale can be distinguished, separated by sulci. The anterior transverse temporal sulcus (sulcus temporalis transversus anterior) separates the planum polare from the transverse temporal gyri of Heschl, the two transverse temporal gyri are subdivided by the intermediate transverse temporal sulcus (sulcus temporalis transversus intermedius), and the posterior transverse temporal sulcus (sulcus temporalis transversus posterior) separates the posterior transverse temporal gyrus from the planum temporale. There is usually one transverse gyrus of Heschl on the left and two on the right (Heschl, 1878;Marie et al., 2015;Tzourio-Mazoyer and Mazoyer, 2017). These transverse gyri contain the primary auditory cortex. The planum temporale is on the left usually larger than on the right (von Economo and Horn, 1930;Geschwind and Levitsky, 1968;Galaburda et al., 1978;Ide et al., 1999;Tzourio-Mazoyer and Mazoyer, 2017). The posterior part of the superior temporal gyrus forms the sensory or receptive language area of Wernicke (1874).
The temporal lobe is the location of strong asymmetries of its surface with a strong leftward asymmetry of the planum temporale (von Economo and Horn, 1930; Geschwind and FIGURE 2 | Sulci definition on the 3-D renderings of the T1 MNI single subject brain: (A) Lateral view; left hemisphere on the left. From the frontal pole to the occipital pole, the following sulci are indicated: the superior frontal sulcus (dark green), the inferior frontal sulcus (red), the anterior, horizontal ramus of the lateral, Sylvian sulcus (light green), the ascending, vertical ramus of the lateral sulcus (cyan), the diagonal sulcus (yellow), the precentral sulcus (purple), the central, Rolandic sulcus (red), the postcentral sulcus (cyan), the intraparietal and intraoccipital sulci (purple), the anterior limit of the occipital lobe, corresponding in its inferior part to the anterior occipital sulcus (light green), the transverse occipital sulcus (yellow), and the inferior occipital sulcus (pink).
The triangular insula of Reil lies in the depths of the lateral sulcus and is covered by the frontal, frontoparietal, parietal, and temporal opercula (Türe et al., 1999;Naidich et al., 2004;Morel FIGURE 5 | Gyri and sulci of the medial aspect of the standard brain (from Nieuwenhuys et al., 2015; with permission from Springer Nature  Figure 8). The limen insulae, the insular threshold or frontotemporal junction, forms the transition from the anterior perforated substance on the basal aspect of the frontal lobe to the insula. The insula is surrounded by the circular sulcus of the insula (sulcus circularis insulae of Reil) or periinsular sulcus, and contains several vertically directed gyri, usually three short gyri (gyri breves insulae), anterior, middle and posterior, and one or two long gyri (gyri longi insulae), anterior and posterior, separated by the central sulcus of the insula (sulcus centralis insulae) or transverse insular sulcus of Eberstaller. The three short gyri converge to the apex of the insula, and are joined to the orbital part of the inferior frontal gyrus by a short annectant gyrus, the transverse insular gyrus (gyrus transversus insulae of Eberstaller).
The lateral aspect of the parietal lobe (lobus parietalis) shows the postcentral gyrus (gyrus postcentralis), the postcentral sulcus (sulcus postcentralis), and the superior and inferior parietal lobules (lobulus parietalis superior andinferior), numbered P1 and P2, respectively, and separated by the intraparietal sulcus (sulcus intraparietalis). Dorsally, the parietal lobe is connected with the occipital lobe by the parietooccipital arc (arcus parietooccipitalis) of Gratiolet. Another "pli de passage" connects the posterior part of the angular gyrus with the superior occipital gyrus. In monkeys, the intraparietal sulcus contains numerous intraparietal areas (AIP, LIP, MIP, PIP, and VIP; Rizzolatti et al., 1998;ten Donkelaar, 2011;Zilles and Amunts, 2012). In an fMRI study, Seitz and Binkofski (2003) identified AIP and VIP in the human brain. Two cytoarchitectonic areas were identified and termed hIP (human IntraParietal) 1 and hIP2 in the anterior part of the intraparietal sulcus (Choi et al., 2006), which may be the anatomical correlates of VIP and AIP, respectively (see also Zlatkina and Petrides, 2014). A third intraparietal area, hIP3, was delineated in the anterior medial wall of the intraparietal sulcus, directly across hIP1 and hIP2 (Scheperjans et al., 2008a,b).
The inferior parietal lobule (IPL) consists of the supramarginal and angular gyri (gyrus supramarginalis and angularis), both of which can be further subdivided (see Caspers et al., 2012). The supramarginal gyrus surrounds the posterior ascending ramus of the lateral sulcus and can be subdivided into five areas. The angular gyrus lies around the caudal end of the superior temporal gyrus and is composed of two areas. The first intermediate sulcus (sulcus intermedius primus of Jensen) may subdivide the inferior parietal lobule into the supramarginal and angular gyri, and the second intermediate sulcus (sulcus intermedius secundus of Eberstaller) may be found posterior to the Jensen sulcus, dividing the angular gyrus into anterior and posterior parts.
The transverse parietal sulcus (sulcus parietalis transversus of Brissaud) may subdivide the superior parietal lobule (SPL) into anterior and posterior portions, when it extends on the superolateral aspect of the cerebrum. The SPL includes the preparietal area, the superior parietal area, each with subdivisions (see Scheperjans et al., 2008a,b). The parietal operculum (operculum parietale) contains four cytoarchitectonic areas (OP1-OP4), corresponding to the secondary somatosensory cortex (Eickhoff et al., 2006a,b).
Most of the occipital lobe (lobus occipitalis) is found on the medial aspect of the cerebrum. An imaginary line between the parietooccipital sulcus superiorly and the preoccipital notch inferiorly indicates the border between the occipital lobe and the parietal and temporal lobes. On the superolateral aspect, the following occipital gyri and sulci can be found: the superior occipital gyrus (O1 or gyrus occipitalis superior), the middle occipital gyrus (O2 or gyrus occipitalis medius), the upper and lower parts of which are separated by the lunate sulcus (sulcus lunatus), the inferior occipital gyrus (O3 or gyrus occipitalis inferior) and the descending occipital gyrus (gyrus occipitalis descendens of Ecker). An inferior occipital sulcus (sulcus occipitalis inferior) may divide the lower part of O2 from O3. For variations of the gyri and sulci on the occipital lobe convexity, see Ono et al. (1990), Alves et al. (2012) and Malikovic et al. (2012).

INFEROMEDIAL SURFACE OF THE CEREBRAL HEMISPHERE
On the inferomedial surface of the cerebral hemisphere, interlobar sulci include the continuation of the central sulcus, the cingulate sulcus, the sulcus of the corpus callosum, the parietoccipital sulcus, the subparietal sulcus and the collateral sulcus (Figure 9; and Table 2). The cingulate sulcus (sulcus cinguli or "scissure limbique" of Broca, 1878b) runs parallel to the corpus callosum and ascends above the posterior part (the splenium) of the corpus callosum toward the superior  For a summarizing figure, see Figure 6.
margin of the hemisphere. It gives off a marginal branch or sulcus (ramus marginalis or sulcus marginalis). The cingulate sulcus continues around the rostrum of the corpus callosum, where it is also known as the superior rostral sulcus (sulcus rostralis superior). This sulcus may continue as the inferior rostral sulcus (sulcus rostralis inferior), which separates the straight gyrus from the medial surface of the frontal lobe (see Figure 5). Immediately rostral to the ascending part of the cingulate sulcus courses the medial end of the central sulcus.
The cingulate sulcus divides the medial aspect of the cerebral cortex into an outer and an inner zone. The outer zone is composed of the medial part of the superior frontal gyrus (F1 or gyrus frontalis superior) and the paracentral lobule (lobulus paracentralis), which surrounds the medial end of the central sulcus, and has frontal and parietal components. Frequently, a series of furrows delineates the paracingulate sulcus (sulcus paracinguli), which separates the medial division of the superior frontal gyrus from the paracingulate gyrus (gyrus paracinguli; see Figure 2B), also known as the external cingulate gyrus (Ono et al., 1990). This gyrus is separated ventrally by the cingulate sulcus from the cingulate gyrus (Ono et al., 1990;Paus et al., 1996;Ide et al., 1999). Such a double-parallel pattern, where the paracingulate sulcus surrounds the cingulate sulcus, was found in 24% of either hemisphere in Ono's cases. Ide et al.  (1999) found a single sulcus more frequently on the right (69%) than on the left (31%) hemispheres, whereas the double pattern was more frequent on the left (68%) than right (32%) hemispheres.
The inner zone, separated from the corpus callosum by the sulcus of the corpus callosum (sulcus corporis callosi), and earlier known as the fornicate gyrus (gyrus fornicatus of Meynert), is formed by the cingulate gyrus (gyrus cinguli). The cingulate gyrus can be divided into four parts: an anterior part, a midcingulate cortex, a posterior part and a retrosplenial part (Vogt and Palomero-Gallagher, 2012). The cingulate gyrus is continuous through a narrowing (isthmus gyri cinguli) with the parahippocampal gyrus (gyrus parahippocampalis or T5) in the temporal lobe. The collateral sulcus (sulcus collateralis, also known as the medial occipitotemporal sulcus) separates T5 from T4, the temporal part of the fusiform gyrus (gyrus fusiformis, also known as the lateral occipitotemporal gyrus). Areas of the fusiform gyrus within the inferotemporal cortex are part of the ventral visual stream area (see Rosenke et al., 2018), and they process higher-order visual information associated with faces, limbs, words, and places. Caspers et al. (2013) identified two areas, FG1 and FG2, medial and lateral in the posterior part of the fusiform gyrus, respectively. Lorenz et al. (2017) identified two new areas, FG3 and FG4, medial and lateral in the midfusiform gyrus, respectively, separated by the midfusiform sulcus (sulcus fusiformis medius). The occipitotemporal sulcus (sulcus occipitotemporalis, also known as the lateral occipitotemporal sulcus) separates the medial part of the inferior temporal gyrus (T3 or gyrus temporalis inferior) from T4. Various classifications for the temporal sulci and gyri have been published (Ono et al., 1990;Duvernoy, 1992;Hanke, 1997;  2 | Sulci and gyri on the inferomedial surface of the cerebral hemisphere (based on TNA, 2017; ten Donkelaar et al., 2018).

English official terms and synonyms
Latin official terms and synonyms Abbreviations and acronyms Eponyms  Huntgeburth Chau et al., 2014;Cikla et al., 2016) with different relations between the collateral and rhinal sulci and patterns of the various sulci.
The posterior part of the medial cerebral cortex has two deep sulci, which converge toward the splenium. The interlobar parietooccipital sulcus (sulcus parietooccipitalis of Gratiolet) separates the parietal and occipital lobes, and the lobar calcarine sulcus (sulcus calcarinus) divides the occipital lobe into a dorsal part, the cuneus (O6) and a ventral part, the lingual or medial occipitotemporal gyrus (O5; gyrus lingualis or gyrus occipitotemporalis medialis). The lingual gyrus may be divided into two parts by the lingual sulcus (sulcus lingualis). The primary visual cortex is mainly found on both sides of the calcarine sulcus. Below the lingual gyrus, separated by the occipitotemporal sulcus (sulcus occipitotemporalis), lies the occipital part of the fusiform or lateral occipitotemporal gyrus (O4; gyrus fusiformis or gyrus occipitotemporalis lateralis). The visual areas outside the striate area (area striata) are grouped together as the extrastriate areas (areae extrastriatae; for current views and further discussion, see Wang et al., 2015).
The naming of two "olfactory gyri" in the TA (1998) suggested that there were clearly identifiable gyral structures; this is not true. These terms persisted from the old description of the "rhinencephalon" (see Gastaut and Lammers, 1961;Stephan, 1975) and have been deleted in the TNA (2017). The real olfactory cortex is the piriform or primary olfactory cortex (cortex piriformis or cortex olfactorius primarius), which can be divided into frontal and temporal parts (Allison, 1954;Heimer et al., 1977Heimer et al., , 1999Zilles, 2004;Zilles and Amunts, 2012;ten Donkelaar et al., 2018).
In the TNA (2017), the TA names for the sulci and gyri in the orbitofrontal cortex have been corrected. Lateral to the olfactory sulcus, there are two longitudinally directed sulci, the medial orbital sulcus (sulcus orbitalis medialis) and the lateral orbital sulcus (sulcus orbitalis lateralis), which are joined by the transverse orbital sulcus (sulcus orbitalis transversus) to form an H or a K pattern (Duvernoy, 1992;Chiavaras and Petrides, 2000;Öngur et al., 2003;Petrides and Pandya, 2012;Rolls et al., 2015;ten Donkelaar et al., 2018). The following orbital gyri can be found: the medial orbital gyrus (gyrus orbitalis medialis) between the olfactory sulcus and the medial orbital sulcus, the anterior orbital gyrus (gyrus orbitalis anterior), the cortex rostral to the transverse orbital sulcus, the posterior orbital gyrus (gyrus orbitalis posterior), the cortex caudal to the transverse orbital sulcus, and the lateral orbital gyrus (gyrus orbitalis lateralis) lateral to the lateral orbital sulcus. The caudal parts of the medial and posterior orbital gyri merge to form the posteromedial orbital lobule (lobulus orbitalis posteromedialis) as described by Türe et al. (1999) and Naidich et al. (2004). The posteromedial orbital lobule gives rise to the transverse insular gyrus (gyrus transversus insulae). Mai and Majtanik (2017) also distinguished a posterolateral orbital region (regio orbitalis posterolateralis) between the posterior orbital gyrus and the orbital part of the inferior frontal gyrus.

THE LIMBIC LOBE
The cingulate gyrus and the parahippocampal gyrus form a border (limbus) around the corpus callosum and the brain stem (Broca, 1878b). Broca subdivided his grand lobe limbique into inner (the hippocampal formation) and outer (the cingulate and parahippocampal) rings for which now the general descriptive term limbic lobe is used (Heimer et al., 2008;Nieuwenhuys et al., 2008). The "scissure limbique" separates the limbic lobe from the rest of the cerebral cortex and can be seen as an interlobar sulcus (Duvernoy, 1992;ten Donkelaar et al., 2018). It consists of (Figure 11; and Table 3): the anterior paraolfactory sulcus (sulcus paraolfactorius anterior) in the subcallosal area, the cingulate sulcus (sulcus cinguli), part of the subparietal sulcus, the rostral part of the parietooccipital sulcus, the collateral sulcus (sulcus collateralis), and the rhinal sulcus (sulcus rhinalis).
The limbic lobe consists of an inner ring (known as the intralimbic gyrus in the French literature; Testut and Latarjet,  Donkelaar et al., 2018).
The perirhinal cortex (cortex perirhinalis) is a periarchicortical structure (Suzuki and Amaral, 1994;Augustinack et al., 2013) around the perirhinal sulcus (sulcus perirhinalis) and corresponds to the transentorhinal region (regio transentorhinalis) of Braak and Braak (1992). Its laminar structure is comparable to that of the entorhinal cortex. Adjacent to the perirhinal cortex is the ectorhinal cortex (cortex ectorhinalis), an isocortical part of the inferior temporal surface, but sometimes included in the perirhinal cortex (Ding and Van Hoesen, 2010).
Classically, the hippocampal formation (formatio hippocampi) is divided into three, originally adjacent, allocortical areas (Stephan, 1975;Duvernoy, 1998;ten Donkelaar, 2011): (1) the dentate gyrus (gyrus dentatus); (2) the hippocampus proper or Ammon's horn (hippocampus proprius or cornu ammonis); and (3) the subiculum (subiculum). These three structures are known as the archicortex. A small indentation between the fimbria and the molecular layer of the dentate gyrus has been termed the fimbriodentate sulcus (sulcus fimbriodentatus) by Gastaut and Lammers (1961). Several periallocortical structures, including the entorhinal cortex, the presubiculum and the parasubiculum, all parts of the parahippocampal gyrus, have also been included within the term "hippocampal formation, " since they are closely related and share a common pattern of projections (Insausti and Amaral, 2012). The TNA (2017), however, follows the classic view.
The hippocampal formation develops from the medial pallium, and during the outgrowth of the cerebral hemispheres, first caudalwards and subsequently ventralwards and rostralwards, the retrocommissural part of the hippocampus (pars retrocommissuralis hippocampi) becomes situated in the temporal lobe (see ten Donkelaar et al., 2014). Rudiments of the supracommissural part of the hippocampus (pars supracommissuralis hippocampi) can be found above the corpus callosum as the indusium griseum (indusium griseum), a thin cell layer, flanked by the lateral longitudinal stria of Lancisi (stria longitudinalis lateralis), also known as the taenia tecti, and the medial longitudinal stria of Lancisi (stria longitudinalis medialis), also known as the taenia libera. The precommissural part of the hippocampus (pars precommissuralis hippocampi) disappears.
Macroscopically, the following parts of the hippocampus can be distinguished (Duvernoy, 1998;Insausti and Amaral, 2012;ten Donkelaar et al., 2018): (1) the pes hippocampi or pes of the hippocampus (pes hippocampi) showing the hippocampal digitations (digitationes hippocampi); (2) the head or anterior segment (caput or pars anterior); (3) the body or middle segment (corpus or pars media); (4) the tail or posterior segment (cauda or pars posterior); and (5) the gyri of Andreas Retzius or subsplenial gyri (dentes subiculi or gyri subspleniales) described by Gustav Retzius (Retzius, 1896) in honor of his father Anders Adolf, a series of small bumps marking the caudal limit of the CA1 field. Here, the parahippocampal gyrus meets the retrosplenial region caudally. Two obliquely oriented small gyri are located deep to the gyri of Andreas Retzius. The medial one is the fasciola cinerea (fasciola cinerea), the visible caudal end of the dentate gyrus as described by Giacomini (1884) and Klingler (1948). The lateral gyrus, corresponding to the caudal end of the CA3 field, is the fasciolar gyrus (gyrus fasciolaris).

CONCLUSIONS
In this review, an attempt for a common terminology for the cerebral gyri and sulci is presented, largely following the recently published Terminologia Neuroanatomica (TNA, 2017). The differences found in the modern literature mainly concern: 1. The use of the term fissure for certain deep sulci; here, it is advocated to restrict the term fissure to the interhemispheric fissure, and to use the term sulcus for all other grooves; 2. The use of the topographical terms lateral and medial occipitotemporal gyri for the fusiform gyrus and the lingual gyrus, respectively. 3. These terms and some other frequently used terms are placed as synonyms, both in English and Latin in the TNA, and are summarized in Tables 1-3. 4. We suggest a simple system of abbreviations with capitals for gyri and small letters for sulci. 5. In the near future, several new subdivisions will have to be included. The TNA database at the FIPAT websites (www. unifr.ch/ifaa; http://FIPAT.library.dal.ca) will be regularly updated.