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http://rgm22.nig.ac.jp/mediawiki-ogareport/index.php/For_Gray_anatomy_normalization
 * The anterior end is named the genu, and is bent downward and backward in front of the septum pellucidum; diminishing rapidly in thickness, it is prolonged backward under the name of the rostrum, which is connected below with the lamina terminalis. The anterior cerebral arteries are in contact with the under surface of the rostrum; they then arch over the front of the genu, and are carried backward above the body of the corpus callosum.	  101
 * The posterior end is termed the splenium and constitutes the thickest part of the corpus callosum. It overlaps the tela chorioidea of the third ventricle and the mid-brain, and ends in a thick, convex, free border. A sagittal section of the splenium shows that the posterior end of the corpus callosum is acutely bent forward, the upper and lower parts being applied to each other.	  102
 * The superior surface is convex from before backward, and is about 2.5 cm. wide. Its medial part forms the bottom of the longitudinal fissure, and is in contact posteriorly with the lower border of the falx cerebri. Laterally it is overlapped by the cingulate gyrus, but is separated from it by the slit-like callosal fissure. It is traversed by numerous transverse ridges and furrows, and is covered by a thin layer of gray matter, the supracallosal gyrus, which exhibits on either side of the middle line the medial and lateral longitudinal striæ, already described (page 827).	  103
 * The inferior surface is concave, and forms on either side of the middle line the roof of the lateral ventricle. Medially, this surface is attached in front to the septum pellucidum; behind this it is fused with the upper surface of the body of the fornix, while the splenium is in contact with the tela chorioidea.	  104
 * On either side, the fibers of the corpus callosum radiate in the white substance and pass to the various parts of the cerebral cortex; those curving forward from the genu into the frontal lobe constitute the forceps anterior, and those curving backward into the occipital lobe, the forceps posterior. Between these two parts is the main body of the fibers which constitute the tapetum and extend laterally on either side into the temporal lobe, and cover in the central part of the lateral ventricle.	  105
 * The Lateral Ventricles (ventriculus lateralis) (Fig. 734).—The two lateral ventricles are irregular cavities situated in the lower and medial parts of the cerebral hemispheres, one on either side of the middle line. They are separated from each other by a median vertical partition, the septum pellucidum, but communicate with the third ventricle and indirectly with each other through the interventricular foramen. They are lined by a thin, diaphanous membrane, the ependyma, covered by ciliated epithelium, and contain cerebrospinal fluid, which, even in health, may be secreted in considerable amount. Each lateral ventricle consists of a central part or body, and three prolongations from it, termed cornua (Figs. 735, 736).	  106
 * The central part (pars centralis ventriculi lateralis; cella) (Fig. 737) of the lateral ventricle extends from the interventricular foramen to the splenium of the corpus callosum. It is an irregularly curved cavity, triangular on transverse section, with a roof, a floor, and a medial wall. The roof is formed by the under surface of the corpus callosum; the floor by the following parts, enumerated in their order of position, from before backward: the caudate nucleus of the corpus striatum, the stria terminalis and the terminal vein, the lateral portion of the upper surface of the thalamus, the choroid plexus, and the lateral part of the fornix; the medial wall is the posterior part of the septum pellucidum, which separates it from the opposite ventricle.
 * The anterior cornu (cornu anterius; anterior horn; precornu) (Fig. 736) passes forward and lateralward, with a slight inclination downward, from the interventricular foramen into the frontal lobe, curving around the anterior end of the caudate nucleus. Its floor is formed by the upper surface of the reflected portion of the corpus callosum, the rostrum. It is bounded medially by the anterior portion of the septum pellucidum, and laterally by the head of the caudate nucleus. Its apex reaches the posterior surface of the genu of the corpus callosum.	  108
 * The posterior cornu (cornu posterius; postcornu) (Figs. 737, 788) passes into the occipital lobe, its direction being backward and lateralward, and then medialward. Its roof is formed by the fibers of the corpus callosum passing to the temporal and occipital lobes. On its medial wall is a longitudinal eminence, the calcar avis (hippocampus minor), which is an involution of the ventricular wall produced by the calcarine fissure. Above this the forceps posterior of the corpus callosum, sweeping around to enter the occipital lobe, causes another projection, termed the bulb of the posterior cornu. The calcar avis and bulb of the posterior cornu are extremely variable in their degree of development; in some cases they are ill-defined, in others prominent.
 * The inferior cornu (cornu inferior; descending horn; middle horn; medicornu) (Fig. 739), the largest of the three, traverses the temporal lobe of the brain, forming in its course a curve around the posterior end of the thalamus. It passes at first backward, lateralward, and downward, and then curves forward to within 2.5 cm. of the apex of the temporal lobe, its direction being fairly well indicated on the surface of the brain by that of the superior temporal sulcus. Its roof is formed chiefly by the inferior surface of the tapetum of the corpus callosum, but the tail of the caudate nucleus and the stria terminalis also extend forward in the roof of the inferior cornu to its extremity; the tail of the caudate nucleus joins the putamen. Its floor presents the following parts: the hippocampus, the fimbria hippocampi, the collateral eminence, and the choroid plexus. When the choroid plexus is removed, a cleft-like opening is left along the medial wall of the inferior cornu; this cleft constitutes the lower part of the choroidal fissure.	  110
 * The hippocampus (hippocampus major) (Figs. 739, 740) is a curved eminence, about 5 cm. long, which extends throughout the entire length of the floor of the inferior cornu. Its lower end is enlarged, and presents two or three rounded elevations or digitations which give it a paw-like appearance, and hence it is named the pes hippocampi. If a transverse section be made through the hippocampus, it will be seen that this eminence is produced by the folding of the wall of the hemisphere to form the hippocampal fissure. The main mass of the hippocampus consists of gray substance, but on its ventricular surface is a thin white layer, the alveus, which is continuous with the fimbria hippocampi.	  111
 * The collateral eminence (eminentia collateralis) (Fig. 740) is an elongated swelling lying lateral to and parallel with the hippocampus. It corresponds with the middle part of the collateral fissure, and its size depends on the depth and direction of this fissure. It is continuous behind with a flattened triangular area, the trigonum collaterale, situated between the posterior and inferior cornua.	  112
 * The fimbria hippocampi is a continuation of the crus of the fornix, and will be discussed with that body; a description of the choroid plexus will be found on page 840.	  113
 * The corpus striatum has received its name from the striped appearance which a section of its anterior part presents, in consequence of diverging white fibers being mixed with the gray substance which forms its chief mass. A part of the corpus striatum is imbedded in the white substance of the hemisphere, and is therefore external to the ventricle; it is termed the extraventricular portion, or the lentiform nucleus; the remainder, however, projects into the ventricle, and is named the intraventricular portion, or the caudate nucleus (Fig. 737).	  114
 * The caudate nucleus (nucleus caudatus; caudatum) (Figs. 741, 742) is a pear-shaped, highly arched gray mass; its broad extremity, or head, is directed forward into the anterior cornu of the lateral ventricle, and is continuous with the anterior perforated substance and with the anterior end of the lentiform nucleus; its narrow end, or tail, is directed backward on the lateral side of the thalamus, from which it is separated by the stria terminalis and the terminal vein. It is then continued downward into the roof of the inferior cornu, and ends in the putamen near the apex of the temporal lobe. It is covered by the lining of the ventricle, and crossed by some veins of considerable size. It is separated from the lentiform nucleus, in the greater part of its extent, by a thick lamina of white substance, called the internal capsule, but the two portions of the corpus striatum are united in front (Figs. 743, 744).
 * The lentiform nucleus (nucleus lentiformis; lenticular nucleus; lenticula) (Fig. 741) is lateral to the caudate nucleus and thalamus, and is seen only in sections of the hemisphere. When divided horizontally, it exhibits, to some extent, the appearance of a biconvex lens (Fig. 742), while a coronal section of its central part presents a somewhat triangular outline. It is shorter than the caudate nucleus and does not extend as far forward. It is bounded laterally by a lamina of white substance called the external capsule, and lateral to this is a thin layer of gray substance termed the claustrum. Its anterior end is continuous with the lower part of the head of the caudate nucleus and with the anterior perforated substance.	  116
 * In a coronal section through the middle of the lentiform nucleus, two medullary laminæ are seen dividing it into three parts. The lateral and largest part is of a reddish color, and is known as the putamen, while the medial and intermediate are of a yellowish tint, and together constitute the globus pallidus; all three are marked by fine radiating white fibers, which are most distinct in the putamen (Fig. 744).	  117
 * The gray substance of the corpus striatum is traversed by nerve fibers, some of which originate in it. The cells are multipolar, both large and small; those of the lentiform nucleus contain yellow pigment. The caudate and lentiform nuclei are not only directly continuous with each other anteriorly, but are connected to each other by numerous fibers. The corpus striatum is also connected: (1) to the cerebral cortex, by what are termed the corticostriate fibers; (2) to the thalamus, by fibers which pass through the internal capsule, and by a strand named the ansa lentiformis; (3) to the cerebral peduncle, by fibers which leave the lower aspect of the caudate and lentiform nuclei.
 * The claustrum (Figs. 742, 744) is a thin layer of gray substance, situated on the lateral surface of the external capsule. Its transverse section is triangular, with the apex directed upward. Its medial surface, contiguous to the external capsule, is smooth, but its lateral surface presents ridges and furrows corresponding with the gyri and sulci of the insula, with which it is in close relationship. The claustrum is regarded as a detached portion of the gray substance of the insula, from which it is separated by a layer of white fibers, the capsula extrema (band of Baillarger). Its cells are small and spindle-shaped, and contain yellow pigment; they are similar to those of the deepest layer of the cortex.	  119
 * The nucleus amygdalæ (amygdala) (Fig. 741), is an ovoid gray mass, situated at the lower end of the roof of the inferior cornu. It is merely a localized thickening of the gray cortex, continuous with that of the uncus; in front it is continuous with the putamen, behind with the stria terminalis and the tail of the caudate nucleus.	  120

after
The anterior end is named the {genu [FMA24974:Knee]}, and is bent downward and backward in front of the {septum pellucidum [FMA61842:Septum of telencephalon; FMA61844:Septum pellucidum]}; diminishing rapidly in thickness, it is prolonged backward under the name of the rostrum, which is connected below with the {lamina terminalis [FMA61975:Lamina terminalis]}. The {anterior cerebral arteries [FMA50028:Anterior cerebral artery]} are in contact with the under surface of the rostrum; they then arch over the front of the {genu [FMA24974:Knee]}, and are carried backward above the {body of the corpus callosum [FMA61947:Body of corpus callosum]}. 101   The posterior end is termed the {splenium [FMA7196:Spleen]} and constitutes the thickest part of the {corpus callosum [FMA61946:Genu of corpus callosum; FMA61947:Body of corpus callosum; FMA86464:Corpus callosum]}. It overlaps the {tela chorioidea of the third ventricle [FMA78463:Tela choroidea of third ventricle]} and the {mid-brain [FMA61993:Midbrain]}, and ends in a thick, convex, free border. A sagittal section of the {splenium [FMA7196:Spleen]} shows that the posterior end of the {corpus callosum [FMA61946:Genu of corpus callosum; FMA61947:Body of corpus callosum; FMA86464:Corpus callosum]} is acutely bent forward, the upper and lower parts being applied to each other. 102   The superior surface is convex from before backward, and is about 2.5 cm. wide. Its medial part forms the bottom of the {longitudinal fissure [FMA83727:Longitudinal fissure]}, and is in contact posteriorly with the lower border of the {falx cerebri [FMA83967:Falx cerebri]}. Laterally it is overlapped by the {cingulate gyrus [FMA62434:Cingulate gyrus]}, but is separated from it by the slit-like callosal fissure. It is traversed by numerous transverse {ridges [FMA75035:Crest]} and furrows, and is covered by a thin layer of {gray matter [FMA67242:Gray matter of neuraxis]}, the {supracallosal gyrus [FMA61920:Supracallosal gyrus]}, which exhibits on either side of the middle line the medial and {lateral longitudinal stri [FMA62439:Lateral longitudinal stria]}æ, already described (page 827). 103   The inferior surface is concave, and forms on either side of the middle line the roof of the {lateral ventricle [FMA78448:Lateral ventricle]}. Medially, this surface is attached in front to the {septum pellucidum [FMA61842:Septum of telencephalon; FMA61844:Septum pellucidum]}; behind this it is fused with the upper {surface of the body [FMA61695:Body surface]} of the {fornix [FMA61965:Fornix of forebrain]}, while the {splenium [FMA7196:Spleen]} is in contact with the {tela chorioidea [FMA242849:Tela choroidea]}. 104   On either side, the fibers of the {corpus callosum [FMA61946:Genu of corpus callosum; FMA61947:Body of corpus callosum; FMA86464:Corpus callosum]} radiate in the {white substance [FMA83929:White matter of neuraxis]} and pass to the various parts of the {cerebral cortex [FMA61830:Cerebral cortex]}; those curving forward from the {genu [FMA24974:Knee]} into the {frontal lobe [FMA61824:Frontal lobe]} constitute the forceps anterior, and those curving backward into the {occipital lobe [FMA67325:Occipital lobe]}, the forceps posterior. Between these two parts is the main body of the fibers which constitute the {tapetum [FMA77208:Tapetum]} and extend laterally on either side into the {temporal lobe [FMA61825:Temporal lobe]}, and cover in the {central part of the lateral ventricle [FMA83703:Body of lateral ventricle]}. 105   The {Lateral Ventricles [FMA78448:Lateral ventricle]} ({ventriculus lateralis [FMA74520:Frontal horn of lateral ventricle; FMA83700:Occipital horn of lateral ventricle; FMA83701:Temporal horn of lateral ventricle; FMA83703:Body of lateral ventricle]}) (Fig. 734).—The two {lateral ventricles [FMA78448:Lateral ventricle]} are irregular {cavities [:]} situated in the lower and medial parts of the {cerebral hemispheres [FMA61817:Cerebral hemisphere]}, one on either side of the middle line. They are separated from each other by a median vertical partition, the {septum pellucidum [FMA61842:Septum of telencephalon; FMA61844:Septum pellucidum]}, but communicate with the {third ventricle [FMA78454:Third ventricle]} and indirectly with each other through the {interventricular foramen [FMA75351:Interventricular foramen]}. They are lined by a thin, diaphanous membrane, the {ependyma [FMA242791:Ependyma of neuraxis]}, covered by ciliated {epithelium [FMA9639:Portion of epithelium]}, and contain {cerebrospinal fluid [FMA20935:Cerebrospinal fluid]}, which, even in health, may be secreted in considerable amount. Each {lateral ventricle [FMA78448:Lateral ventricle]} consists of a central part or body, and three prolongations from it, termed cornua (Figs. 735, 736). 106   The {central part (pars centralis ventriculi lateralis; cella) (Fig. 737) of the lateral ventricle [FMA83703:Body of lateral ventricle]} extends from the {interventricular foramen [FMA75351:Interventricular foramen]} to the {splenium of the corpus callosum [FMA61948:Splenium of corpus callosum]}. It is an irregularly curved cavity, triangular on transverse section, with a roof, a floor, and a medial wall. The roof is formed by the under surface of the {corpus callosum [FMA61946:Genu of corpus callosum; FMA61947:Body of corpus callosum; FMA86464:Corpus callosum]}; the floor by the following parts, enumerated in their order of position, from before backward: the {caudate nucleus [FMA61833:Caudate nucleus]} of the {corpus striatum [FMA77616:Corpus striatum]}, the {stria terminalis [FMA61974:Stria terminalis]} and the {terminal vein [FMA50997:Superior thalamostriate vein]}, the lateral portion of the upper surface of the {thalamus [FMA62007:Thalamus]}, the {choroid plexus [FMA61934:Choroid plexus of cerebral hemisphere]}, and the lateral part of the {fornix [FMA61965:Fornix of forebrain]}; the medial wall is the posterior part of the {septum pellucidum [FMA61842:Septum of telencephalon; FMA61844:Septum pellucidum]}, which separates it from the opposite ventricle. The anterior cornu ({cornu anterius [FMA74520:Frontal horn of lateral ventricle]}; anterior horn; precornu) (Fig. 736) passes forward and lateralward, with a slight inclination downward, from the {interventricular foramen [FMA75351:Interventricular foramen]} into the {frontal lobe [FMA61824:Frontal lobe]}, curving around the anterior end of the {caudate nucleus [FMA61833:Caudate nucleus]}. Its floor is formed by the upper surface of the reflected portion of the {corpus callosum [FMA61946:Genu of corpus callosum; FMA61947:Body of corpus callosum; FMA86464:Corpus callosum]}, the rostrum. It is bounded medially by the anterior portion of the {septum pellucidum [FMA61842:Septum of telencephalon; FMA61844:Septum pellucidum]}, and laterally by the {head of the caudate nucleus [FMA61852:Head of caudate nucleus]}. Its apex reaches the posterior surface of the {genu of the corpus callosum [FMA61946:Genu of corpus callosum]}. 108   The {posterior cornu [FMA83700:Occipital horn of lateral ventricle]} ({cornu posterius [FMA83700:Occipital horn of lateral ventricle]}; postcornu) (Figs. 737, 788) passes into the {occipital lobe [FMA67325:Occipital lobe]}, its direction being backward and lateralward, and then medialward. Its roof is formed by the fibers of the {corpus callosum [FMA61946:Genu of corpus callosum; FMA61947:Body of corpus callosum; FMA86464:Corpus callosum]} passing to the temporal and {occipital lobes [FMA67325:Occipital lobe]}. On its medial wall is a longitudinal eminence, the {calcar avis [FMA78438:Calcarine spur; FMA83707:Calcar avis]} ({hippocampus [FMA62493:Hippocampus; FMA74038:Hippocampal formation]} minor), which is an involution of the {ventricular wall [FMA13884:Wall of ventricle]} produced by the {calcarine fissure [FMA83749:Calcarine sulcus]}. Above this the forceps posterior of the {corpus callosum [FMA61946:Genu of corpus callosum; FMA61947:Body of corpus callosum; FMA86464:Corpus callosum]}, sweeping around to enter the {occipital lobe [FMA67325:Occipital lobe]}, causes another projection, termed the {bulb of the posterior cornu [FMA83699:Bulb of occipital horn of lateral ventricle]}. The {calcar avis [FMA78438:Calcarine spur; FMA83707:Calcar avis]} and {bulb of the posterior cornu [FMA83699:Bulb of occipital horn of lateral ventricle]} are extremely variable in their degree of development; in some cases they are ill-defined, in others prominent. The {inferior cornu [FMA83701:Temporal horn of lateral ventricle]} (cornu inferior; descending horn; middle horn; medicornu) (Fig. 739), the largest of the three, traverses the {temporal lobe [FMA61825:Temporal lobe]} of the {brain [FMA50801:Brain]}, forming in its course a curve around the posterior end of the {thalamus [FMA62007:Thalamus]}. It passes at first backward, lateralward, and downward, and then curves forward to within 2.5 cm. of the apex of the {temporal lobe [FMA61825:Temporal lobe]}, its direction being fairly well indicated on the {surface of the brain [FMA86594:Surface of brain]} by that of the {superior temporal sulcus [FMA83783:Superior temporal sulcus]}. Its roof is formed chiefly by the inferior surface of the {tapetum [FMA77208:Tapetum]} of the {corpus callosum [FMA61946:Genu of corpus callosum; FMA61947:Body of corpus callosum; FMA86464:Corpus callosum]}, but the {tail of the caudate nucleus [FMA61854:Tail of caudate nucleus]} and the {stria terminalis [FMA61974:Stria terminalis]} also extend forward in the roof of the {inferior cornu [FMA83701:Temporal horn of lateral ventricle]} to its extremity; the {tail of the caudate nucleus [FMA61854:Tail of caudate nucleus]} joins the {putamen [FMA61834:Putamen]}. Its floor presents the following parts: the {hippocampus [FMA62493:Hippocampus; FMA74038:Hippocampal formation]}, the {fimbria hippocampi [FMA83866:Fimbria of hippocampus]}, the {collateral eminence [FMA83706:Collateral eminence]}, and the {choroid plexus [FMA61934:Choroid plexus of cerebral hemisphere]}. When the {choroid plexus [FMA61934:Choroid plexus of cerebral hemisphere]} is removed, a cleft-like opening is left along the medial wall of the {inferior cornu [FMA83701:Temporal horn of lateral ventricle]}; this cleft constitutes the lower part of the {choroidal fissure [FMA74512:Choroidal fissure]}. 110   The {hippocampus [FMA62493:Hippocampus; FMA74038:Hippocampal formation]} ({hippocampus major [FMA62493:Hippocampus]}) (Figs. 739, 740) is a curved eminence, about 5 cm. long, which extends throughout the entire length of the floor of the {inferior cornu [FMA83701:Temporal horn of lateral ventricle]}. Its lower end is enlarged, and presents two or three rounded elevations or digitations which give it a paw-like appearance, and hence it is named the {pes hippocampi [FMA84032:Set of hippocampal digitations]}. If a transverse section be made through the {hippocampus [FMA62493:Hippocampus; FMA74038:Hippocampal formation]}, it will be seen that this eminence is produced by the folding of the wall of the hemisphere to form the {hippocampal fissure [FMA83747:Hippocampal sulcus]}. The main mass of the {hippocampus [FMA62493:Hippocampus; FMA74038:Hippocampal formation]} consists of {gray substance [FMA67242:Gray matter of neuraxis]}, but on its ventricular surface is a thin white layer, the {alveus [FMA83867:Alveus of hippocampus]}, which is continuous with the {fimbria hippocampi [FMA83866:Fimbria of hippocampus]}. 111   The {collateral eminence [FMA83706:Collateral eminence]} ({eminentia collateralis [FMA83706:Collateral eminence]}) (Fig. 740) is an elongated swelling lying lateral to and parallel with the {hippocampus [FMA62493:Hippocampus; FMA74038:Hippocampal formation]}. It corresponds with the middle part of the {collateral fissure [FMA83751:Collateral sulcus]}, and its size depends on the depth and direction of this fissure. It is continuous behind with a flattened triangular area, the {trigonum collaterale [FMA83713:Collateral trigone]}, situated between the posterior and {inferior cornua [FMA83701:Temporal horn of lateral ventricle]}. 112   The {fimbria hippocampi [FMA83866:Fimbria of hippocampus]} is a continuation of the {crus of the fornix [FMA61969:Posterior column of fornix of forebrain]}, and will be discussed with that body; a description of the {choroid plexus [FMA61934:Choroid plexus of cerebral hemisphere]} will be found on page 840. 113   The {corpus striatum [FMA77616:Corpus striatum]} has received its name from the striped appearance which a section of its anterior part presents, in consequence of diverging white fibers being mixed with the {gray substance [FMA67242:Gray matter of neuraxis]} which forms its chief mass. A part of the {corpus striatum [FMA77616:Corpus striatum]} is imbedded in the {white substance [FMA83929:White matter of neuraxis]} of the hemisphere, and is therefore external to the ventricle; it is termed the extraventricular portion, or the {lentiform nucleus [FMA77615:Lentiform nucleus]}; the remainder, however, projects into the ventricle, and is named the intraventricular portion, or the {caudate nucleus [FMA61833:Caudate nucleus]} (Fig. 737). 114   The {caudate nucleus [FMA61833:Caudate nucleus]} ({nucleus caudatus [FMA61833:Caudate nucleus]}; {caudatum [FMA61833:Caudate nucleus]}) (Figs. 741, 742) is a pear-shaped, highly arched gray mass; its broad extremity, or {head [FMA7154:Head]}, is directed forward into the anterior cornu of the {lateral ventricle [FMA78448:Lateral ventricle]}, and is continuous with the {anterior perforated substance [FMA61891:Anterior perforated substance]} and with the anterior end of the {lentiform nucleus [FMA77615:Lentiform nucleus]}; its narrow end, or tail, is directed backward on the lateral side of the {thalamus [FMA62007:Thalamus]}, from which it is separated by the {stria terminalis [FMA61974:Stria terminalis]} and the {terminal vein [FMA50997:Superior thalamostriate vein]}. It is then continued downward into the roof of the {inferior cornu [FMA83701:Temporal horn of lateral ventricle]}, and ends in the {putamen [FMA61834:Putamen]} near the apex of the {temporal lobe [FMA61825:Temporal lobe]}. It is covered by the lining of the ventricle, and crossed by some {veins [FMA63814:Set of veins]} of considerable size. It is separated from the {lentiform nucleus [FMA77615:Lentiform nucleus]}, in the greater part of its extent, by a thick lamina of {white substance [FMA83929:White matter of neuraxis]}, called the {internal capsule [FMA61950:Internal capsule]}, but the two portions of the {corpus striatum [FMA77616:Corpus striatum]} are united in front (Figs. 743, 744). The {lentiform nucleus [FMA77615:Lentiform nucleus]} ({nucleus lentiformis [FMA77615:Lentiform nucleus]}; {lenticular nucleus [FMA77615:Lentiform nucleus]}; lenticula) (Fig. 741) is lateral to the {caudate nucleus [FMA61833:Caudate nucleus]} and {thalamus [FMA62007:Thalamus]}, and is seen only in sections of the hemisphere. When divided horizontally, it exhibits, to some extent, the appearance of a biconvex {lens [FMA58241:Lens]} (Fig. 742), while a {coronal [FMA264717:Coronale]} section of its central part presents a somewhat triangular outline. It is shorter than the {caudate nucleus [FMA61833:Caudate nucleus]} and does not extend as far forward. It is bounded laterally by a lamina of {white substance [FMA83929:White matter of neuraxis]} called the {external capsule [FMA61959:External capsule]}, and lateral to this is a thin layer of {gray substance [FMA67242:Gray matter of neuraxis]} termed the {claustrum [FMA67440:Claustrum]}. Its anterior end is continuous with the lower part of the {head of the caudate nucleus [FMA61852:Head of caudate nucleus]} and with the {anterior perforated substance [FMA61891:Anterior perforated substance]}. 116   In a {coronal [FMA264717:Coronale]} section through the middle of the {lentiform nucleus [FMA77615:Lentiform nucleus]}, two medullary laminæ are seen dividing it into three parts. The lateral and largest part is of a reddish color, and is known as the {putamen [FMA61834:Putamen]}, while the medial and intermediate are of a yellowish tint, and together constitute the {globus pallidus [FMA61835:Globus pallidus; FMA61839:Lateral globus pallidus; FMA61840:Medial globus pallidus; FMA62469:Lateral medullary lamina of globus pallidus; FMA62470:Medial medullary lamina of globus pallidus]}; all three are marked by fine radiating white fibers, which are most distinct in the {putamen [FMA61834:Putamen]} (Fig. 744). 117   The {gray substance [FMA67242:Gray matter of neuraxis]} of the {corpus striatum [FMA77616:Corpus striatum]} is traversed by {nerve fibers [FMA5914:Nerve fiber]}, some of which originate in it. The cells are multipolar, both large and small; those of the {lentiform nucleus [FMA77615:Lentiform nucleus]} contain yellow pigment. The {caudate [FMA61833:Caudate nucleus]} and {lentiform nuclei [FMA84037:Set of lentiform nuclei]} are not only directly continuous with each other anteriorly, but are connected to each other by numerous fibers. The {corpus striatum [FMA77616:Corpus striatum]} is also connected: (1) to the {cerebral cortex [FMA61830:Cerebral cortex]}, by what are termed the corticostriate fibers; (2) to the {thalamus [FMA62007:Thalamus]}, by fibers which pass through the {internal capsule [FMA61950:Internal capsule]}, and by a strand named the ansa lentiformis; (3) to the {cerebral peduncle [FMA62394:Peduncle of midbrain; FMA72464:Cerebral crus]}, by fibers which leave the lower aspect of the {caudate [FMA61833:Caudate nucleus]} and {lentiform nuclei [FMA84037:Set of lentiform nuclei]}. The {claustrum [FMA67440:Claustrum]} (Figs. 742, 744) is a thin layer of {gray substance [FMA67242:Gray matter of neuraxis]}, situated on the lateral surface of the {external capsule [FMA61959:External capsule]}. Its transverse section is triangular, with the apex directed upward. Its medial surface, contiguous to the {external capsule [FMA61959:External capsule]}, is smooth, but its lateral surface presents {ridges [FMA75035:Crest]} and furrows corresponding with the gyri and sulci of the {insula [FMA67329:Insula]}, with which it is in close relationship. The {claustrum [FMA67440:Claustrum]} is regarded as a detached portion of the {gray substance [FMA67242:Gray matter of neuraxis]} of the {insula [FMA67329:Insula]}, from which it is separated by a layer of white fibers, the {capsula extrema [FMA61960:Extreme capsule]} (band of Baillarger). Its cells are small and spindle-shaped, and contain yellow pigment; they are similar to those of the deepest layer of the {cortex [FMA15632:Adrenal cortex; FMA61109:Cortex]}. 119   The {nucleus amygdalæ [FMA61841:Amygdala]} ({amygdala [FMA61841:Amygdala]}) (Fig. 741), is an ovoid gray mass, situated at the lower end of the roof of the {inferior cornu [FMA83701:Temporal horn of lateral ventricle]}. It is merely a localized thickening of the gray {cortex [FMA15632:Adrenal cortex; FMA61109:Cortex]}, continuous with that of the {uncus [FMA74884:Uncus]}; in front it is continuous with the {putamen [FMA61834:Putamen]}, behind with the {stria terminalis [FMA61974:Stria terminalis]} and the {tail of the caudate nucleus [FMA61854:Tail of caudate nucleus]}. 120