Release December 18, Date Added December 18, Version 1. Operating Systems. Operating Systems Android. Additional Requirements Compatible with 2. Total Downloads Downloads Last Week 0. Report Software. Related Apps. Fitbit Free. Track your daily goals and progress over time. Reach your weight loss goals with the calorie counter on your Android device. The primary visual area, the cortical area from the cerebellum. The fourth ventricle is said to have where the visual fibers first arrive in the cerebral cortex, a floor, which is the brainstem, and a roof see Figure is located along the banks of the calcarine fissure.
This 20A. The roof is divided into an upper and lower area is commonly called area 17 described with Figures portion. The upper part consists of a band of white 39A and 39B. The adjacent areas of the occipital lobe matter known as the superior medullary velum see also are visual association areas, also known as areas 18 and The lower part of the roof of this ventricle is The corpus callosum in this particular specimen does occupied by choroid plexus, which has not been pre- not have the usual white matter appearance that would served on this specimen.
The septum pellucidum, a membrane The cerebellum lies behind or above the fourth which divides the lateral ventricle of one hemisphere ventricle. It has been sectioned through its midline from that of the other side see Figure 28A , has been portion, the vermis. Although it is not necessary to removed, thereby exposing one of the lateral ventricles name all of the various parts of the vermis, it is useful to which is seen to be situated inferior to the corpus callo- know two of them: the lingula and the nodulus.
The sum. Above the corpus callosum is an important gyrus reason for knowing these is evident when describing which is part of the limbic system, the cingulate gyrus the cerebellum; see Figure The lingula is that part see Figures 74 and The nodulus is that part of the vermis paired diencephalon see Figures 3, 4, and 9.
The thala- lying adjacent to the lower portion of the roof of the mic portion is separated from the hypothalamic part by fourth ventricle. MRI imaging is the brain after a series of views are taken from many the way the brain is seen in clinical settings. The view perspectives. In this view the bones of the skull are presented in this figure is a T1-weighted image see bright, the CSF is dark, and the brain tissue gray, not below. Note that the cerebrospinal fluid is dark in this clear.
This image can be obtained in several seconds, image, including the subarachnoid space and cisterns even with a very sick patient. It uses an extremely tissue of the scalp are well demarcated. Again there is By comparing this view with the photographic view of a computer reconstruction of the images. The three parts of the brainstem — midbrain, An intermediate setting allows the structures of the pons and medulla — can be identified, with the tectum interior of the brain to be seen; this method produces colliculi seen behind the aqueduct of the midbrain.
With MRI, the bones of the The fourth ventricle separates the cerebellum from the skull are dark, while fatty tissue including bone brainstem. The location of the cerebellar tonsil s should marrow is bright.
Functional of the skull see discussion on tonsillar herniation with MRIs allow us to see which areas of the brain are partic- Figure 8. The location of the cerebello-medullary ularly active during a certain task, based upon the cistern the cisterna magna behind the medulla and just metabolic rate oxygen saturation. They are becoming above the foramen magnum is easily seen see Figure more widely available. Other techniques also visualize the living brain and its The remaining structures are those of the nose and activity, such as the positron emission tomography mouth, which are not within the subject matter in PET scan.
PET uses a very short-acting radioactive this Atlas. Its use is usually restricted to specialized neurologic centers Note on radiological imaging involved in research on the human brain. Corpus callosum 2. Thalamus 3.
Tectum of midbrain 4. Optic chiasm 5. Pons 6. Tonsil of cerebellum 7. Cisterna magna 8. In a DISSECTED VIEW sagittal section, the thickened anterior aspect of the Structures within the depths of the cerebral hemispheres corpus callosum is called the genu, and the thickened include the white matter, cerebral ventricles, and basal posterior portion the splenium neither has been labeled ganglia, all of which are described in the following figures.
The white matter consists of the myelinated axonal Clinical Aspects fibers connecting brain regions. In the spinal cord these In a clinical setting, the corpus callosum is sectioned are called tracts; in the hemispheres these bundles are surgically in individuals with intractable epilepsy classified in the following way also discussed with epilepsy that could not be controlled with anti-convul- Figure 15 : sant medication.
Under laboratory conditions, it has been possible to demonstrate in these individuals how the two In the dissection of this specimen, the brain is again hemispheres of the brain function independently, after seen from the medial view.
Its anterior aspect is on the the sectioning of the corpus callosum. These studies right side of the photograph. Cortical tissue has been show how each hemisphere responds differently to removed as shown in Figure 16 , using blunt dissection various stimuli, and the consequences of information techniques.
If done successfully, the fibers of the corpus not being transferred from one hemisphere to the other. These fibers intermingle with the other fiber bundles which make up the mass of white matter in the depth of the hemisphere. Under the cerebral cortex is the white matter of the processing, allowing for integration of activities for brain.
Various fiber bundles can be dissected not easily example, sensory with motor and limbic. The various using a blunt instrument e.
Some of these, functionally, are the association much importance in a general introduction to the CNS bundles, fibers that interconnect different parts of the except as in Figure 19B. The only deficit is an inability to repeat The arcuate bundle is a specific group of association what has been heard.
This is usually tested by asking the fibers of some importance, particularly on the side patient to repeat single words or phrases whose meaning dominant for language the left hemisphere in most cannot be readily understood e. The formation, circulation, and duct of the midbrain, the cerebral aqueduct, or the locations of the CSF are explained with Figure In the hind- brain region, the area consisting of pons, medulla, and The ventricles of the brain are what remain of the origi- cerebellum, the ventricle widens again to form the nal neural tube, the tube that was present during devel- fourth ventricle see Figures 16 and The channel opment.
The cells of the nervous system, both neurons continues within the CNS and becomes the very narrow and glia, originated from a germinal matrix adjacent to central canal of the spinal cord Figure 2A. The cells multiply and migrate away from the walls of the neural tube, forming the Within the ventricles is specialized tissue, the choroid nuclei and cortex.
As the nervous system develops, the plexus. It is made up of the lining cells of the ventricles, mass of tissue grows and the size of the tube diminishes, called the ependyma, and pia with blood vessels dis- leaving various spaces in different parts of the nervous cussed with Figure The choroid plexus is the tissue system.
It is found in the body and inferior horn of the lateral ventri- The parts of the tube that remain in the hemispheres cle, in the roof of the third ventricle, and in the lower are called the cerebral ventricles, or the lateral half of the roof of the fourth ventricle. The tissue forms ventricles. In Figure 20A, the lateral ventricle of one large invaginations into the ventricles in each of these hemisphere is shown from the lateral perspective.
The exit points are temporal lobes. The major exit is the In addition, there may be an extension into the occipital foramen of Magendie in the midline. There are two ad- lobes, called the occipital or posterior horn. These ditional exits of the CSF laterally from the fourth ventri- lateral ventricles are also called ventricles I and II cle, the foramina of Luschka seen in Figure 20B.
From the foramen of Magendie, the CSF then enters one Each lateral ventricle is connected to the midline third of the enlargements of the subarachnoid space, called a ventricle by an opening, the foramen of Monro inter- cistern, in this case the cisterna magna, the cerebello- ventricular foramen — seen in the medial view of the medullary cistern. It lies below the cerebellum and is brain, Figure The third ventricle is a narrow, slit- found inside the skull, just above the foramen magnum like ventricle between the thalamus on either side and is see Figure 1B.
The CSF then flows in the subarachnoid also called the ventricle of the diencephalon see also space downwards around the spinal cord and upwards Figure 8.
Sectioning through the brain in the midline around the brain discussed with Figure Both lateral ventricles and the such as developmentally, following a meningitis, or by a short interventricular foramen of Monro are visible on tumor in the region. The result is an enlargement of the both sides, connecting each lateral ventricle with the ventricles, called hydrocephalus, which can be seen with midline third ventricle.
It is important to note that the imaging techniques e. Not uncommonly, hydrocephalus in infancy occurs spontaneously, for unknown reasons.
Clinical assessment lateral ventricles within the hemispheres see Figure Untreated hydrocephalus eventually spaces of the lateral and third ventricles see Figure Clinical treatment of this condition, after evaluation of The ventricular channel continues through the aqueduct the causative factor, includes shunting the CSF out of of the midbrain.
CSF then enters the fourth ventricle, the ventricles into one of the body cavities. The fourth ventricle is In adults, hydrocephalus caused by a blockage of the diamond-shaped, and the lateral recesses carry CSF into CSF flow leads to an increase in intracranial pressure, the cisterna magna through the foramina of Luschka, since the sutures are fused and skull expansion is not the lateral apertures, one on each side.
The cause in adults is usually a tumor, and, in Clinical Aspects addition to experiencing the specific symptoms, the The flow of CSF can be interrupted or blocked at patient will usually complain of headache, often in the various key points within the ventricular system. One of early morning. The CSF is formed within the ventricles, This slow circulation is completed by the return of flows through the various channels, exits from within CSF to the venous system.
The return is through the the brain, circulates in the subarachnoid space and cis- arachnoid villi which protrude into the venous sinuses terns around the brain and spinal cord, and is finally re- of the brain, particularly the superior sagittal sinus absorbed into the venous system the venous sinuses.
These can be The physiological barriers between the various compart- seen as collections of villi, called arachnoid granula- ments is also indicated in the illustration. The ventricles of the brain are lined with a layer of cells known as the ependyma. In certain loci within each of There is no real barrier between the intercellular tissue the ventricles the ependymal cells and the pia meet, thus of the brain and the CSF, either through the ependyma forming the choroid plexus, which invaginates into the at all sites other than the choroid plexus or the pia.
Functionally, the choroid plexus has a vascular This lack of barrier is depicted by the arrows, which in- layer, i. The blood vessels of the choroid ments.
Therefore, substances found in detectable plexus are freely permeable, but there is a cellular barrier amounts in the intercellular spaces of the brain may be between the interior of the choroid plexus and the ven- found in the CSF.
The barrier consists of tight junctions and functional, between the blood vessels and the brain between the ependymal cells that line the choroid tissue. This is called the blood-brain barrier BBB and plexus. CSF is actively secreted and an enzyme is in- is situated at the level of the brain capillaries.
Only volved. The ionic and protein composition of CSF is oxygen, carbon dioxide, glucose, and other select, small different from that of serum. CSF leaves the ventricular system from the fourth ven- Sampling of CSF for clinical evaluation, including in- tricle, as indicated schematically in the diagrams. In the flammation of the meninges meningitis , is performed intact brain, this occurs via the medially placed foramen almost always in the lumbar cistern discussed with of Magendie and the two laterally placed foramina of Figures 1A and 1B.
Luschka described in the previous illustrations. There are two aspects to this involvement. It longing to the forebrain. This neuronal mass is found seems that different parts of the basal ganglia are con- deep within the cerebral hemispheres. Our understand- cerned with the speed and magnitude of a movement.
In ing of the functional role of the basal ganglia is derived addition, some of the structures that make up the basal largely from disease states affecting these neurons.
In ganglia are thought to influence cognitive aspects of general, humans with lesions in the basal ganglia have motor control, helping to plan the sequence of tasks some form of motor dysfunction movement disorder needed for purposeful activity. This process is some- — dyskinesia.
From the strictly anatomical point of view, the basal Clinical Aspects ganglia are collections of neurons located within the The functional role of this large collection of neurons is hemispheres. Traditionally, this would include the best illustrated by clinical conditions affecting this neu- caudate nucleus, the putamen, the globus pallidus, ronal system — abnormal movements, such as chorea and the amygdala. Although the caudate and putamen jerky movements , athetosis writhing movements , are separated from each other anatomically, they are and tremors rhythmic movements.
The most common histologically the same neurons, and are known as the condition that affects this group of neurons is striatum. A person with this disease has diffi- ically found together and are called the lentiform or culty initiating movements, loses facial expressiveness lenticular nucleus. From the functional point of view taking on a mask-like appearance, and has muscular and based upon the complex pattern of interconnec- rigidity, slowing of movements bradykinesia , and a tions, two other nuclei should be included with the de- tremor of the hands when at rest that goes away with scription of the basal ganglia: the subthalamic nucleus purposeful movements and in sleep.
The amygdala is now The other major disease that affects the basal ganglia is included with the limbic system see Section D. Overall, the basal ganglia receive much of their input Note on terminology: The term ganglia refers to a col- from the cortex, the motor areas of the cortex, as well as lection of cells in the peripheral nervous system.
There are intricate con- Therefore, the anatomically correct name for this group nections between the various parts of the system in- of neurons should be the basal nuclei. Few texts use this volving different neurotransmitters , and the output is term. Most clinicians would be hard-pressed to change directed via the thalamus mainly to premotor, supple- to the use of this term, so the traditional name remains mentary motor, and frontal cortical areas.
Therefore, the in use. When viewing the basal ganglia from the lateral per- spective, one sees only the putamen part. In fact, it is composed of the caudate with the putamen as discussed with Figure two nuclei see Figure 24 : putamen and globus pal- The caudate and the putamen are histologically lidus.
It is situated laterally and is deep in the hemi- alike and are collectively called the neostriatum, or spheres within the central white matter. Sectioning of simply the striatum. Both the caudate and the lentiform 79B. The inferior portions of the putamen and globus nuclei are found below the level of the corpus pallidus are found at the level of the anterior commis- callosum.
These ventral parts of the lentiform nucleus may In Figure 23 the basal ganglia are shown in isolation have a limbic connection discussed with Figure 85B. The other temporal lobe structures of the two sides dis- various parts of the caudate nucleus are easily recog- cussed with Figure The head of the caudate The other two nuclei of the functional basal ganglia — nucleus is large and actually intrudes into the space of the subthalamus and substantia nigra — are not shown the anterior horn of the lateral ventricle see Figures 27 in this illustration.
The body of the caudate nucleus is consider- ably smaller and lies above the thalamus see Figure The view in Figure 24 has been obtained by removing all This subdivision of the globus pallidus is quite impor- parts of the basal ganglia of one hemisphere, except the tant functionally. The ganglia — the subthalamic nucleus part of the dien- two portions of this nucleus are seen: the putamen later- cephalon and the substantia nigra of the midbrain.
The functional connections of these nuclei are discussed as part of the motor system see Figures 50 and The caudate nucleus and the putamen receive the inputs into the basal nuclei.
As has been explained previously, A distinct collection of neurons is also found in the the caudate and putamen are, in fact, the same neurons ventral region, composed in part of neurons belonging embryologically. Together they are known as the to the basal nuclei — the nucleus accumbens. The neostriatum. In some texts they are simply called the nucleus accumbens is unique in that it seems to consist striatum. Strands of cells may be seen connecting the of a mix of neurons from the basal ganglia and from the various portions of the caudate with the putamen.
This limbic structures in the region discussed with the nuclear structure has been separated into two distinct limbic system, Figure 85B. These connecting strands illustrated in Figure As fiber systems develop, namely the internal capsule see Figure 26 , In Figure 25 the basal ganglia are visualized deep in the these nuclei become separated from each other by the hemisphere, from the lateral perspective. The various anterior limb of the internal capsule. Some connecting parts include the caudate nucleus, the lentiform nucleus, strands of tissue can still be found in the adult brain on and also the amygdala.
Included in this view is the ven- a few horizontal sections through the lowermost parts of tricular system as in Figure 20A and the thalamus, these nuclei. The internal capsule, which consists of a collection of fibers described with Figure 26 is situated between the All three parts of the caudate nucleus — the head, body, lentiform nucleus and the head of the caudate, and and tail — are situated adjacent to the lateral ventricle.
A hori- In fact, the head protrudes into the anterior horn of the zontal section through the brain at the level of the lateral lateral ventricle see Figure The body of the caudate fissure would reveal all these structures see Figure The white matter bundles that course between parts of the basal ganglia and the diencephalon are collectively Below the level of the internal capsule is the midbrain.
The The descending fibers of the internal capsule are contin- internal capsule is a group of fibers located at a specific uous with those found in the cerebral peduncle of the location within the cerebral hemispheres — between the midbrain.
A parcellation of the descending fibers occurs diencephalon the thalamus and the various parts of in the cerebral peduncle, where the cortico-pontine the basal ganglia. These so-called projection fibers are fibers are found in the outer and inner thirds of the pe- axons going to and coming from the cerebral cortex, duncle, and the cortico-bulbar and cortico-spinal fibers linking the cortex with the diencephalon thalamus , are located in the middle third see also Figure This fiber system neuraxis.
These ascending and descending fibers are all forms its anterior limb; called projection fibers discussed with Figure The base of the funnel would The fiber system that runs between the thalamus be the internal capsule. The main point is that the medially and the lentiform nucleus laterally is the various fiber systems, both ascending and descending, posterior limb of the internal capsule.
The posterior are condensed together in the region of the internal limb carries sensory information from thalamus to capsule. For Figure 28B. In this view, the internal capsule of each reasons that are not clearly understood, these blood side is seen to be V-shaped.
The anterior portion vessels are prone to occlusion which destroys the sur- between the caudate and lentiform is the anterior rounding axons. Because of the high packing density of limb. The portion between the lentiform nucleus and the axons in this region, a small lesion can create exten- the thalamus is the posterior limb. These cortico-pontine fibers descend in both the anterior and posterior limbs of the internal capsule. Some strands of gray the horizontal plane, at the level of the lateral fissure.
The posterior limb of the inter- system. Understanding the topography of the structures nal capsule separates the lentiform nucleus from the tha- seen in this view is immeasurably important when the lamus. The major ascending sensory tracts and the student enters the clinical setting.
The basal ganglia are observable when the brain is sectioned at this level. The head of the caudate nucleus Lateral to the lentiform nucleus is another thin strip of is seen, protruding into the lateral ventricle. The tissue, the claustrum. The functional contribution of this lentiform nucleus is shaped somewhat like a lens and small strip of tissue is not really known.
Lateral to this is is demarcated by white matter. The outer part, the the cortex of the insula see Figure Posteriorly, putamen, has neurons that are identical to the caudate behind the thalamus, the cerebellum is visible. It is also possible to see the atrium portion of the lateral The inner portion, the globus pallidus, is functionally ventricle, deep within the parietal lobe. The ventricle is different and contains many more fibers and therefore is sectioned at this level as it enters into the temporal lobe lighter in color.
Depending upon the level of the section, and is becoming the inferior horn of the lateral ventricle it is sometimes possible as in the right side of the pho- see Figure 20A. The third ventricle can be seen situated tograph in Figure 27 to see the two subdivisions of the between the thalamus of both sides.
A view similar to this is commonly presented in brain scans of patients — CTs and MRIs — as shown in the The white matter medial to the lentiform nucleus is the following figures. The cerebellum can be recognized with its horizontal plane as the anatomical specimen shown in characteristic folia 8 in the illustration. The CSF the previous illustration. The radiological images of the cistern, called the quadrigeminal plate cistern, behind brain are done at an angle in order to minimize the the tectal plate the colliculi; also known as the dense bones of the posterior cranial fossa, which impair quadrigeminal plate; discussed with Figure 7 is a very the viewing of the structures brainstem and cerebel- important landmark for the neuroradiologist seen also lum of the posterior cranial fossa.
The outer Clinical Aspects cortical tissue can be seen, with gyri and sulci. The A regular CT can show areas of increased density e. Note that the infarct , as well as changes in the size and shifting of the CSF is dark black in the ventricles 2 and 3 in the il- ventricles. Tumors may be seen as an abnormal area of lustration and in the cisterns 7 in the illustration.
A CT can also be The ventricular space in the frontal lobes is the anterior enhanced by injecting an iodinated compound into the horn of the lateral ventricle on each side see Figure 27, blood circulation and noting whether it escapes into the also Figures 20A and 20B , separated in the midline by brain tissue because of leakage in the blood-brain- the septum pellucidum.
The septum has been removed barrier BBB; see Figure This examination is invalu- from the specimen shown in Figure 16, a mid-sagittal able in the assessment of a neurological patient in the view of the brain and brainstem. Head of caudate nucleus 2. Lateral ventricle anterior horn 3. Third ventricle 4. Lentiform nucleus 5. Internal capsule posterior limb 6. Thalamus 7. Quadrigeminal plate cistern 8. In addi- Figure 28B is a view of the brain taken in the same plane tion, the area of the internal capsule is also seen.
The lateral ven- The MRI has proved to be invaluable in assessing lesions tricle posteriorly see number 5 is cut at the level of its of the CNS — infarcts, tumors, plaques of multiple scle- widening — the atrium — as it curves into the temporal rosis, and numerous other lesions. Lentiform nucleus 3. Thalamus 4. Internal capsule posterior limb 5. The plane of this section is Various parts of the basal ganglia are seen in this view, as somewhat asymmetric, and includes the parietal and has been described with the illustration of the ventricles temporal lobes.
At the outer margins of the ventricle body is a dark nuclear structure, the body of the The external aspect of the hemispheres is composed of caudate nucleus. More laterally is the lentiform nucleus; the cerebral cortex, seen as the gray matter. If the link is not responding kindly inform us through comment section. We will fixed it soon. We highly encourage our visitors to purch ase orig inal books from the respected publishers. If someone with copyrights wants us to remove this content, please contact us.
Functional imaging helps to identify the parts of the brain that become active during our thoughts and actions, and reveals brain regions where drugs act to produce their neurological and psychiatric effects. Complementary experimental approaches in animals—such as mapping neural connections, localizing particular neuroactive chemicals within different brain regions, and determining the effects of lesions—provide the neuroscientist and clinician with the tools to study the biological substrates of disordered thought and behavior.
To interpret this wealth of information requires a high level of neuroanatomical competence.
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