Understanding the Telencephalon: Structure and Functions

1. The Telencephalon

2. External feature • The telencephalon consists of right and left cerebral hemisphere, partially separated by cerebral longitudinal fissure. • The cerebral transverse fissure intervenes between the hemispheres and the cerebellum • Each hemisphere has three surfaces: superolateral, medial and inferior

3. Three principal sulci • Central sulcus中央沟 • Lateral sulcus 外侧沟 • Parietooccipital sulcus 顶枕沟 Central sulcus Parietooccipital sulcus Lateral sulcus

4. Five lobes • Frontal lobe 额叶 • Parietal lobe 顶叶 • Temporal lobe 颞叶 • Occipital lobe 枕叶 • Insular lobe 岛叶 Parietal lobe Insular lobe Frontal lobe Occipital lobe Temporal lobe

5. Sulci and gyri of Superolateral surface Frontal lobe: • Precentral sulcus 中央前沟 • Superior frontal sulcus 额上沟 • Inferior frontal sulcus 额下沟 • Precentral gyrus 中央前回 • Superior frontal gyrus 额上回 • Middle frontal gyrus 额中回 • Inferior frontal gyrus 额下回

6. Sulci and gyri of Superolateral surface Precentral gyrus Precentral sulcus Superior frontal sulcus Inferior frontal sulcus Superior, middle and inferioe frontal gyri

7. Parietal lobe: • Postcentral sulcus 中央后沟 • Postcentral gyrus中央后回 • Intraparietal sulcus 顶内沟 • Superior parietal lobule 顶上小叶 • Inferior parietal lobule 顶下小叶 • Supramarginal gyrus 缘上回 • Angular gyrus 角回

8. Sulci and gyri of Superolateral surface Postcentral gyrus Postcentral sulcus Superior parietal lobule Intraparietal sulcus Supramarginal gyrus Angular gyrus

9. Temporal lobe: • Superior temporal sulcus 颞上沟 • Inferior temporal sulcus 颞下沟 • Superior temporal gyrus 颞上回 • Middle temporal gyrus 颞中回 • Inferior temporal gyrus 颞下回 • Transverse temporal gyri 颞横回

10. Sulci and gyri of Superolateral surface Superior temporal sulcus Superior temporal gyrus Inferior temporal sulcus Middle temporal gyrus Inferior temporal gyrus

11. Transverse temporal gyri

12. Sulci and gyri of Superolateral surface Precentral gyrus Precentral sulcus Postcentral gyrus Postcentral sulcus Superior frontal sulcus Superior parietal lobule Inferior frontal sulcus Superior, middle and inferioe frontal gyri Supramarginal gyrus Angular gyrus Superior temporal sulcus Superior temporal gyrus Inferior temporal sulcus Middle temporal gyrus Inferior temporal gyrus

13. Sulci and gyri of medial surface • Corpus callosum 胼胝体 • Callosal sulcus 胼胝体沟 • Cingulate gyrus 扣带沟 • Cingulate sulcus 扣带回 • Marginal ramus 缘支 • Paracentral lobule 中央旁小叶 • Calcarine sulcus 距状沟 • Cuneus 楔叶 • Lingual gyrus 舌回

14. Sulci and gyri of medial surface Paracentral lobule Corpus callosum Callosal sulcus Marginal ramus cingulate gyrus Parietooccipital sulcus Cingulate sulcus Cuneus Calcarine sulcus Lingual gyrus

15. Sulci and gyri of inferior surface • Olfactory bulb 嗅球 • Olfactory tract 嗅束 • Olfactory trigone 嗅三角 • Anterior perforated substance 前穿质 • Collateral sulcus 侧副沟 • Occipitotemporal sulcus 枕颞沟 • Medial occipitotemporal gyrus 枕颞内侧回 • Lateral occipitotemporal gyrus 枕颞外侧回 • Hippocampal sulcus 海马沟 • Parahippocampal gyrus 海马旁回 • Uncus 钩 • Hippocampus 海马 • Dentate gyrus 齿状回 Hippocampal formation海马结构

16. Inferior surface Olfactory bulb Olfactory tract Uncus Olfactory trigone Anterior perforated substance Occipitotemporal sulcus Parahippocampal gyrus Medial and lateral occipitotemporal gyri Collateral sulcus

17. Hippocampus Hippocampal formation Dentate gyrus

18. Histology of the cerebral cortex • Archicortex原皮质(hippocampal formation 海马结构) • Paleocortex古皮质 (rhinencephalon 嗅脑) • Neocortex新皮质 (most of cerebral cortex) 3 cell layers 6 cell layers

20. Functional location of cerebral cortex

21. First somatic motor area 第一躯体运动区 Position: located in precentral gyrus and anterior portion of paracentral lobule

22. First somatic motor area第一躯体运动区 Characters • Representation is inverted, but head and face are upright • A body part is represented by a cortical area proportional to its use rather than its size • Receiving fibers from postcentral gyrus, VA, VL and VPL, sending out fibers to form pyramidal tract, controlling voluntary movements

23. First somatic sensory area第一躯体感觉区 Position－lies in postcentral gyrus and posterior portion of paracentral lobule

24. First somatic sensory area第一躯体感觉区 Characters • Sensory representation, like motor area, is crossed and inverted • Receiving and interpret sensation from opposite side of body

25. Auditory area 听区 • Located in transverse temporal gyri • Receive auditory information from both ears

26. Visual area 视区 • Lie on either side of calcarine sulcus in medial surface of occipital lobe • Visual cortex of one hemisphere receives impression from temporal part of retina of same side and nasal part of opposite side • Lesions of visual cortex produce contralateral homonymous visual field defections

27. Vestibular area平衡觉区: located in front of superior temporal gyrus • Olfactory area 嗅觉区: located near the uncus • Taste area 味觉区: located at frontal operculum

28. Language area 语言中枢 It is dominant in left hemisphere in right-handed person • Motor speech area运动性语言中枢 • Located in posterior portion of inferior frontal gyrus • Damage: motor aphasia • Writing area书写中枢 • Located in posterior portion of middle frontal gyrus • Damage: agraphia • Auditory speech area听觉性语言中枢 • Located in posterior portion of superior temporal gyrus • Lesion: sensory aphasia • Visual speech area视觉性语言中枢 • Located in angular gyrus • Lesion: alexia

29. Internal structures Lateral ventricle侧脑室 • Position: located in cerebral hemispheres • Four parts • Central part: lies in parietal lobe • Anterior horn: extends into frontal lobe • Posterior horn extend into occipital lobe • Inferior horn: extend into temporal lobe

30. Communication lateral ventricle → interventricular foramen → third ventricle

31. Basal nuclei 基底核 • Corpus striatum 纹状体 • Lentiform nucleus 豆状核 • Caudate nucleus 尾状核 • Claustrum 屏状核 • Amygdaloid body 杏仁体 Globus pallidus 苍白球 －paleostriatum 旧纹状体 putamen 壳 Neostriatum 新纹状体

33. White matter Association fibers 联络纤维 Run between gyri within the same hemisphere • Cerebral arcuate fibers 大脑弓状纤维 • Superior longitudinal fasciculi 上纵束 • Inferior longitudinal fasciculi 下纵束 • Uncinate fasciculus 钩束 • Cingulum 扣带

34. Commissural fibers 连合纤维 － run between left and right hemisphere • Corpus callosum胼胝体: rostrum, genu, trunk, splenium • Anterior commissure 前连合 • Fornix and commissure of fornix 穹隆和穹隆连合

35. Projection fibers投射纤维: connect cortex with lower part of brain and spinal cord and they include both ascending and descending fibers Internal capsule • Position: a thick lamina of white matter lying between caudate nucleus, thalamus and lentiform nucleus

37. Three parts • Anterior limb of internal capsule 内囊前肢 • Lies between caudate nucleus and lentiform nucleus • Containing frontopontine tract and anterior thalamic radiation • Genu of internal capsule 内囊膝 • Is angle at which anterior and posterior limbs meet • Containing corticonuclear tract • Posterior limb of internal capsule内囊后肢 • Lies between thalamus and lentiform nucleus • Contain corticospinal tract, corticorubral tract, central thalamic radiation, parieto-occipito-temporo-pontine tract, acoustic radiation and optic radiation

38. Anterior thalamic radiation Head of caudate nucleus Frontopontine tract Corticonuclear tract Lentiform nucleus Corticorubral tract Corticospinal tract Parieto-occipito- temporo-pontine tract Dorsal thalamus Central thalamic radiation Acoustic radiation Medial geniculate body Optic radiation Lateral geniculate body

39. Limbic system边缘系统 • Composition • Limbic lobe: includes septal area, cingulated gyrus, parahippocampal gyrus, hippocampus, dentate gyrus, temporal pole, anterior part of insular lobe and so on • Associated subcortical nuclei: amygdaloid body, septal nuclei, hypothalamus, epithalamus, anterior nucleus group of thalamus, tegmentum of midbrain • Function: concerned with visceral activities, olfaction, emotion and memory, so this system is called ‘visceral brain’