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An Illustrated Guide to Human Neuroematomy

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An Illustrated Guide to Human Neuroematomy f:N-i,4I}TIA I APPENDIX INTRODUCTION SURFACEANATOMY OF THE BRAIN An Illustrated THE LATERALSURFACE OFTHE BRAIN /o) CrossFeotures Guide to Human (b) SelectedGyri,Sulci, ond Fissures Neuroematomy (c) CerebrolLobes ond the Insulo (d) Mojor Sensory,Motor, ond AssociotionAreos of Cortex THE MEDIALSURFACE OF THE BRAIN FT & (o) BroinStem Structures (b) ForebroinStructures (c) Ventricles THEVENTRALSURFACE OF THE BRAIN THE DORSALSURFACE OFTHE BRAIN (o) Cerebrum (b) CerebrumRernoved (c) Cerebrumond CerebellumRemoved CROSS.SECTIONALANATOMY OF THE BRAIN CROSSSECTION | : FOREBRAINAT THALAMUS-TELENCEPHALON JUNCTION (o) GrossFeotures (b) SelectedCell ond FiberGroups CROSSSECTION 2: FOREBRAINAT MID-THALAMUS (o) GrossFeotures (b) SelectedCell ond FiberGroups CROSSSECTION 3: FOREBRAINATTHALAMUS-MIDBRAIN JUNCTION (o) GrossFeotures (b) Se/eaedCell ond FiberGrouPs CROSSSECTION 4: ROSTRALMIDBRAIN CROSSSECTION 5: CAUDALMIDBRAIN CROSSSECTION 6: PONSAND CEREBELLUM CROSSSECTION 7: ROSTRALMEDULLA CROSSSECTION 8: MID-MEDULLA CROSSSECTION 9: MEDULLA-SPINALCORD JUNCTION THESPINAL CORD THE DORSALSURFACE OF THE SPINAL CORD AND SPINALNERVES THE VENTRAL-LATERAL SURFACE CROSS-SECTIONALANATOMY THEAUTONOMIC NERVOUS SYSTEM THECRANIAL NERVES THEBLOOD SUPPLY OF THE BRAIN VENTRALVIEW LATERALVIEW MEDTALVTEW(BRA|N STEM REMOVED) SELF.QUIZ j:' :: \) fi:; "i'- ,1,.., 206 C HAPTE R 7 . APPENDIX:ANILLUSTRATED GUIDETO HUMAN NEUROANATOMY W INTRODUCTION As we will see in the remainder of the book, a fruitful way to explore the nervous system is to divide it up into functional systems. Thus, the otfac- tlry systemconsists of those parts of the brain that are devoted to the sense of smell, the visual systemincludes those parts that are devoted to vision, and so on. while this functional approach to investigatingnervous sys- "big tem structure has many merits, it can make the picture,,-how all these systemsfit rogether inside the box we call the brain-difficult ro see. The goal of this Illustrated Guide is to help you learn, in advance,atrout some of the anatomy that will be discussedin the subsequentchapters. Here we concentrateon naming the structuresand seeinghow they are related physically;their functional significanceis discussedin the re- mainder of the book The Guide is clrganizedinto six main parts. The first part covers the sur- face anatomy of the brain-the structures that can been seen by inspection of the whole brain, as well as those parts that are visible when the two cerebralhemispheres are separatedby a cut in the midsagittalplane. Next, we explore the cross-sectionalanatomy of the brain, using a seriesof slabs that contain structuresof interest.The brief third and fourth partscover the spinal cord and the autonomic nervous system.The fifth part of the Guide illustratesthe cranial nerves and summarizestheir diversefunctions. The last part illustratesthe blood supply of the brain. The nervoussystem has an astonishingnumber of bits and pieces.In this Guide,we focuson thosestructures that will appearlater in the book when we discussthe various functional systems.Nonetheless, even this abbrevi- ated atlas of neuroanatomy yields a formidable list of new vocabulary. Therefore, to help you learn the terminology, an extensive self-quiz review is provided at the end, in the form of a perforated workbook with labeling exercises. 'W SURFACEANATOMY OF THE BRAIN Imagine that you hold in your hands a human brain that has been dis- sectedfrom the skull. It is wer and spongy and weighs about 1.4 kg (3 lb). Looking down on the brain's dorsal surfacereveals the convoluted surface of the cerebrum. Flipping the brain over shows the complex ven- tral surfacethat normally restson the floor of the skull. Holding the brain ,,ram.s up and looking at its side-the lateral view-shows the horn,, shape of the cerebrum coming off the stalk of the brain stem. The brain stem is shown more clearly if we slice the brain right down the middle and view its medial surface.In the part of the Guide that follows, we will name the important structures that are revealed by such an inspection of the brain. Notice the magnificarionof the drawings: lx is life-size,2X is twice life- size,0.6X is 60"/. of life-size.and so on. 205 Lateral view Medialview 208 c HApTER 7 . AppENDTX:ANTLLUsTMTED GUTDETo HUMAN NEURoANAToMy The Lateral Surface of the Brain (a) Gross Features. This is a life-size drawing of the brain. Gross inspection reveals the three major parts: the large cerebrum, the brain stem that forms its stalk, and the rippled cerebellum. The diminutive olfacrory bulb of the cerebrum can also be seen in this lateral view. Cerebrum Olfactorybulb Cerebellum : i,- " SURFACEANATOMYOFTHE BRAIN (b) Selected Gyri, Sulci, and Fissures. The cerebrum is central gyrus lies immediately posterior to the cenlral sr.rl- noteworthy for its convoluted surface. The bumps are cus, and the precentral gyrus lies immediately anterior to called gyri, and the grooves are called sulci or, if they are the central sulcus. The neurons of the postcentral gyrus especially deep, fissures. The precise pattern of gyri and are involved in somatic sensation (touch; Chapter 12), sulci can vary considerably from individual to individual, and those of the precentral gyrus control voluntary move- but many features are common to all human brains. Some ment (Chapter l4). Neurons in the superior lemporal of the important landmarks are labeled here. The post- gyrlrs are involved in audition (hearing; Chapter ll). Centralsulcus Lateral(Sylvian) fissure (c) Cerebral Lobes and the Insula. By convention, of the cerebrum, bordering both parietal and temporal the cerebrum is subdivided into lobes named after the lobes. A buried piece of the cerebral cortex, called the "island"), bones of the skull that lie over them. The central sulcus insula (Latin for is revealedif the margins of dividesthe lrontal lobe from the parietallobe. The tem- the lateral fissure are gently pulled apart (inset). The pural lobc lies immediately ventral to the deep lateral insula borders and separatesthe temporal and frontal (Sylvian)fissure. The occipitallobe lies at the very back lobes. Frontallobe Occipitallobe 'i'..'.;'"1':,',:'i,.,,i;,,,,:11..rt.r,lr:: .: r',i,,':\irir,i:..4 t,:1,i : . .1,..':rij !l 210 cHAprER 7 . AppENDTX:ANTLLUSTRATEDGUTDEToHUMAN NEURoANAToMy (d) Major Sensory, Ivlotor, and Association Areas of and auditory areas4l and 42 (Chapter lI) are in the Cortex. The cerebral cortex is organized like a patch- temporal lobe. On the inferior surface of the parietal work quilt. The various areas, first identified by Brod- lobe (the operculum) and buried in the insula is gusta- mann, differ from one another in terms of microscopic tory area 43, devoted to the senseof taste (Chapter 8). structure and function. Visual areas L7, 18, and l9 In addition to the analysis of sensory information. the (Chapter l0) are in the occipital lobe, somatic sensory cerebral cortex plays an important role in the control of areas l, l, and 2 (Chapter 12) are in the parietal lobe, voluntary movement. The major motor control areas- primary motor cortex (area4). the supplementary motor area, and the premotor area-lie in the frontal lobe, an- terior to the central sulcus (Chapter I4). In the human brain, large expanses of cortex cannot be simply assigned to sensory or motor functions. These constitute the as- sociation areas of cortex. Some of the more important areasare the prefrontal cortex (Chapters2l and 24), the posteriorparietal cortex (Chapters12, 21, and 24), and the inferotemporalcortex (Chapter24). Brodmann'smao Primarymotor cortex (area4) Supplementarymotor area Somatosensorycortex (area6) (areas3, 1,2) Posteriorparietal cortex Premotorarea (areas5, 7) (area6) Visualcortex (areas17,18, 19) Prefrontalcortex Inferotemporalcortex (areas20,21,37) Auditorycortex (areas41, 42) I Motorareas ffi Sensoryareas Gustatory (area43) ! Associationareas : r.l ffil ji ..:] SURFACEANATOMYOFTHE BRAIN The Medial Surface of the Brain (a) Brain Stem Structures. Splitting the brain down the middle exposesthe medial surface of the cerebrum, shown in this life-sizeillustration. This view also shows the midsagittal cut surface of the brain stem, consisting of the diencephalon(thalanrrrs and h1'llotlralarrrrrs).the rtticltrrairt(teclrrrn and lcgnrentrrrrr),the llorrs,and the nrctlrrlla.(Some anatclmists define the brain stem as con- sistingonly of the midbrain, pons, and medulla.) Thalamus Y( Pinealbody b*^ Hypothalamus Cerebellum 212 c H A pr ER 7 . AppENDtX:ANILLUSTMTED GUIDETo HUMAN NEURoANAToMy (b) Forebrain Structures. Shown here are the im- Some of the axons in the fornix regulate memory portant forebrain structures that can be observed by storage(Chapter 24). viewing the medial surface of the brain. Notice the In the lower illustration, the brain has been tilted cut surfaceof the corpus callosum,a huge bundle of slightly tcl show the positionsof the anrl,gdalaand hip- "phantom axons that connects the two sides of the cerebrum. pocanrpus.These are views" of these struc- The unique contributions of the two cerebral hemi- tures, becausethey cannot be observeddirectly frclm the spheresto human brain function can be studied in surface. Both lie deep to the overlyinll correx. We will patients in which the callosum has been sectioned see them again in cross section later in the Guide. The "almond") (Chapter 20). The lornix is another prominent fiber amygdala (Latin for is important for regulat- bundle that connects the hippocampus on each side ing emotional states(Chapter l8), and the hippocampus "arch.")
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