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    • The Brain II Blood Supply of the CNS and Sectional Anatomy of the Brain (for dental students) Dr.Akram Abood Jaffar Assistant Professor of Human Anatomy M.B.Ch.B., M.Sc., Ph.D.Dr. Akram Jaffar Dr. Akram Jaffar
    • Objectives Blood supply of the brain Enumerate the branches of the internal carotid and vertebral arteries. Map the areas of supply of the anterior, middle and posterior cerebral arteries. Correlate areas of supply of cerebral arteries with functional cortical areas. Describe the position, significance and formation of the circle of Willis. Enumerate the veins draining the brain and the venous sinuses at which they drain. Brain sections Identify features of the cerebral hemispheres in coronal and axial sections at the level of the interventricular foramen. Identify the boundaries of the third ventricle in a mid-sagittal section. Describe the parts of the basal ganglia and their relation to the lateral ventricle. Identify the parts and functions of the limbic system. Describe the major functions of the thalamus and hypothalamus. Describe how the hypothalamus controls the functions of the pituitary gland. Identify the pineal gland, its function and clinical significance. Describe the formation, circulation, and absorption of the CSF. Discuss the properties and function of the CSF. Describe the location and discuss the significance of the brain barriers: blood brain barrier & blood CSF barrier. Further reading • Snell RS (2010): Clinical neuroanatomy. 7th ed. Lippincott Williams and Wilkins. Baltimore.Dr. Akram Jaffar Dr. Akram Jaffar
    • Blood supply of the brainDr. Akram Jaffar Dr. Akram Jaffar
    • Arterial supply Internal carotid a. Vertebral a.Dr. Akram Jaffar Dr. Akram Jaffar
    • Internal carotid artery • Enters the cranial cavity through the carotid canal in the petrous temporal bone. • Traverses the cavernous sinus. • Pierces the roof of the cavernous sinus. • Divides into anterior and middle cerebral arteries. middle cerebral a. Anterior cerebral a. Internal carotid a.Dr. Akram Jaffar Dr. Akram Jaffar
    • Branches of the internal carotid artery Anterior cerebral artery • Passes around the rostrum and genu of the corpus callosum. • Supplies the medial aspect of the frontal and parietal lobes as far back as the parieto- occipital sulcus and a small part of the adjacent lateral surface. Corpus callosum Anterior cerebral a. Effect of occlusion Contralateral hemisenory loss Contralateral hemiparesis Personality changes Leg and footDr. Akram Jaffar Dr. Akram Jaffar
    • Branches of the internal carotid artery Middle cerebral artery • Passes laterally into the lateral sulcus. • Supplies the inferior surface of the frontal lobe, the insula, and all save the periphery of the lateral surface of the hemisphere. middle cerebral a. Contralateral hemisenory loss Lateral sulcus Contralateral hemiparesis Aphasia Face and arm middle cerebral a. Effect of occlusionDr. Akram Jaffar Dr. Akram Jaffar
    • Branches of the internal carotid artery Other branches Ophthalmic a. • Ophthalmic artery  orbit • Anterior choroidal artery  choroid plexus of the lateral ventricle • Posterior communicating artery  posterior cerebral artery Post. communicating a. Ant. Choroidal a. Post. cerebral a.Dr. Akram Jaffar Dr. Akram Jaffar
    • Vertebral artery • Enters the cranial cavity through the foramen magnum. • Unites with its fellow of the opposite side at the lower border of the pons to form the basilar artery Basilar a. pons Vertebral a.Dr. Akram Jaffar Dr. Akram Jaffar
    • Branches of the vertebral artery • Anterior spinal artery – Formed by the union of branches from both vertebral arteries. Ant. spinal a. – Descend in front of the medulla to reach and supply the spinal cord. • Posterior inferior cerebellar artery – Supplies the medulla, lower cerebellum, choroidal branch to the fourth ventricle, and a Ant. spinal a. posterior spinal branch which descends to the spinal cord. PICADr. Akram Jaffar PICA Dr. Akram Jaffar
    • Branches of the basilar artery • Anterior inferior cerebellar artery • Pontine branches • Labyrinthine artery – Pass through the internal acoustic meatus  inner ear Post. Cerebral a. • Superior cerebellar artery • Posterior cerebral arteries. – At the upper pons Ant. Inf. Cerebellar a. Pontine branches Sup cerebellar a. Sup cerebellar a. Post. Cerebral a. Pontine branches Ant. Inf. Cerebellar a.Dr. Akram Jaffar Dr. Akram Jaffar
    • Branches of the basilar artery Posterior cerebral artery • Passes backwards around the cerebral peduncles to reach and supply: – Medial surface of the occipital lobe. – Inferior surfaces of the occipital and temporal lobes and the Post. Cerebral a. adjacent lateral surface Effect of occlusion Impairment of memoryDr. Akram Jaffar Blindness Dr. Akram Jaffar
    • Circle of Willis • Anastomotic ring around the optic chiasma and the pituitary gland. • Provides anastomosis between internal carotid and vertebral system of arteries. Optic chiasma • Formation: Pituitary gland – Anterior, middle and posterior cerebral arteries – anterior and posterior communicating arteries • Central arteries enter the brain through the anterior and posterior perforated substances. Ant. communicating a. central Ant. cerebral a. central Middle cerebral a. Post. communicating a.Dr. Akram Jaffar Post. Cerebral a. Dr. Akram Jaffar
    • Venous drainage of the brain • The veins draining the hemispheres may be divided into superficial and deep veins.Dr. Akram Jaffar Dr. Akram Jaffar
    • Superficial group of veins Superior cerebral veins passing to the superior sagittal sinus Superficial middle cerebral vein passing in the lateral sulcus to the cavernous sinus Inferior cerebral veins passing to the transverse sinusDr. Akram Jaffar Dr. Akram Jaffar
    • Deep group of veins Anterior cerebral vein Deep middle cerebral vein Basal vein Great cerebral vein Internal cerebral vein Basal vein Great cerebral vein Straight sinusDr. Akram Jaffar Dr. Akram Jaffar
    • Sectional anatomy of the brianDr. Akram Jaffar Dr. Akram Jaffar
    • Basal nuclei (ganglia) claustrum Caudate nucleus insula putamen Globus pallidus Caudate nucleus Amygdaloid body Masses of grey matter located deep to the cortex in each cerebral hemisphere Basal ganglia o Corpus striatum: is involved in the Corpus striatum Claustrum Amygdaloid body regulation of movement. o Amygdaloind body: is concerned Caudate nucleus Lentiform nucleus with emotional behavior o Claustrum: uncertain function putamenDr. Akram Jaffar Globus pallidus Dr. Akram Jaffar
    • Ventricualr system Lateral ventricle rostrum Interventricular Anterior horn thalamus foramen us 3rd ventricle lam tha Lateral ventricle splenium Posterior horn Transverse section just below the level of the corpus Lateral ventricle callosum (at the level of the interventricular foramen) Lateral ventricle Lateral ventricle Lateral ventricle 3rd ventricle Cerebral aqueduct 4th ventricle • Lateral ventricle: – Anterior horn – Body – Posterior horn 3rd ventricle Interventricular foramen – Inferior hornDr. Akram Jaffar 4th ventricle Dr. Akram Jaffar
    • Internal capsule claustrum • band of projection fibers, appears in a horizontal section as V- putamen shaped. • Connects the cerebral cortex with Globus lower centers. pallidus An • Has an anterior limb, apex te rio (genu), and a posterior limb. rl im b genu P os us te lam rio rl t ha im b Caudate nucleusDr. Akram Jaffar Dr. Akram Jaffar
    • Caudate nucleus Head of caudate nucleus thalamus body head tail tail • Is C-shaped in three dimensions • Lies within the concavity of the lateral ventricle. • Has an expanded head, a narrow body and a tail. • Thus in a horizontal section only the head and tail of the caudate nucleus appear. • The head of the caudate nucleus bulges into the medial wall of the anterior horn of the lateral ventricle. • The body of the caudate nucleus is located in the floor of the body of the lateral ventricleDr. Akram Jaffar • The tail of the caudate lies in the roof of the inferior horn of the lateral ventricle Dr. Akram Jaffar
    • Corpus striatum claustrum putamen o The head of the caudate nucleus and the lentiform nucleus are connected by fibers and grey matter across the Globus anterior limb of the internal capsule pallidus resulting in a striated appearance (hence the name corpus striatum). An te rio rl im b genu P os te rio rl im b thalamus Caudate nucleusDr. Akram Jaffar Dr. Akram Jaffar
    • Axial section of the brain insula putamen Globus pallidus An te rio Head rl Of im b Caudate genu nucleus Po st er or i lim b thalamusDr. Akram Jaffar MRI Dr. Akram Jaffar
    • The limbic system fornix • Limbic structures: Cingulate gyrus • Cingulate gyrus • Hippocampal formation • Amygdaloid nucleus (part diencephalon of the basal nuclei) Mammilothalamic • Mammillary bodies (part of tract the hypothalamus) • Anterior thalamic nucleus (part of the thalamus). • Fibre tracts: Mamillary bodies Anterior • Fornix Thalamic nuclei • mammilothalamic tract Parahippocampal gyrusDr. Akram Jaffar Dr. Akram Jaffar
    • Hippocampal formation • Consists mainly of the hippocampus and the parahippocampal gyrus. • The hippocampus is a nuclear mass that lies in the floor of the inferior horn of the lateral ventricle. • The axons arising from the hippocampus lie on its surface and form the alveus. • The fibers of the alveus form the fornix . fornix Inferior horn of Lateral ventricle hippocampus alveusDr. Akram Jaffar Parahippocampal Coronal section gyrus Dr. Akram Jaffar
    • Functions of the limbic system This system is widely connected, many of its functions are not clearly understood; nevertheless the limbic system controls: • Emotional behavior such as fear, anger, and the emotions associated with sexual behavior • Recent memory • Olfaction Fear Anger Recent memory SmellDr. Akram Jaffar Emotions Dr. Akram Jaffar
    • Features of a coronal section of the hemispheres • Corpus callosum: • Lies in the depth of the median sagittal Body of lateral fissure. ventricle • Forms a roof for the body of the lateral Body of ventricle. Corpus callosum caudate nucleus • The body of the caudate nucleus lies in men the inferolateral boundary of the body of insula puta the lateral ventricle Globus thalamus pallidus • The tail of the caudate nucleus is tail located at the roof of the inferior horn of the lateral ventricle. 3rd ventricle • Each thalamus lies on either side of the midline forming a floor for the body of Inferior horn the lateral ventricle • The thalami lie on either side of the 3rd ventricle. bodyDr. Akram Jaffar tail The section passes through the body and inferior horn of the C-shaped lateral ventricle Dr. Akram Jaffar
    • Features of a coronal section of the hemispheres • The white matter of the internal capsule is situated between the lentiform Body of lateral nucleus on lateral side and the ventricle thalamus and caudate nucleus on the medial side. Corpus callosum Septum • The body of the fornix is connected to pellucidum the undersurface of the corpus men callosum by the septum pellucidum. puta Globus pallidus fornix • The septum pellucidum forms a septum between the two lateral ventricles tail (anterior horn and body). 3rd ventricle fornix Inferior horn Corpus callosumDr. Akram Jaffar Septum pellucidum Dr. Akram Jaffar
    • The diencephalon thalamus • It consists of nuclear masses, mainly of the thalamus and hypothalamus. • Its cavity is the third ventricle. • The thalamus: – Is egg-shaped. – Function : 3rd ventricle • Mainly: a relay station of sensory impulses: It receives sensory afferents from the spinal cord and brain stem and projects efferents to the primary sensory cortex. • Is also concerned with motor control. Interventricular foramen 3rd ventricle thalamusDr. Akram Jaffar Dr. Akram Jaffar
    • The hypothalamus thalamus • Below the thalamus. • Forms the floor and the inferior part of the lateral wall of the 3rd ventricle. hypothalamus hypothalamusDr. Akram Jaffar Dr. Akram Jaffar
    • The hypothalamus • Behind the optic Optic chiasma the floor of the chiasma 3rd ventricle gives rise to the stalk infundibulum (infundibulum) of the hypophysis cerebri. Hypophysis • cerebri The mamillary bodies lie behind. Mamillary body Optic chiasma Hypophysis cerebri infundibulumDr. Akram Jaffar Mamillary body Dr. Akram Jaffar
    • The pituitary gland (hypophysis cerebri) • Endocrine gland. • Situated in the hypophyseal fossa of the body of the sphenoid bone. • Is closely related to the optic chiasma: – Tumors may produce pressure effects on the adjacent optic chiasma  visual defects. Hypophyseal fossa Optic chiasma Hypophysis cerebriDr. Akram Jaffar Dr. Akram Jaffar
    • Functions of the hypothalamus • Regulation of the autonomic nervous system. • Regulation of endocrine glands through the hypophysis cerebri. • Temperature regulation. thalamus • Regulation of food and water intake. • Control of sleep. hypothalamus infundibulum Hypophysis cerebriDr. Akram Jaffar Dr. Akram Jaffar
    • Parts of the ventricular system ventricle Lateral Lateral to septum pellucidum Interventricular foramen 3rd ventricle Cerebral aqueduct 4th ventricle Central canalDr. Akram Jaffar Dr. Akram Jaffar
    • The choroid plexus Choroid plexus • The ventricles are lined with a single Lateral ventricle epithelial layer called the epindyma. • In each ventricle the lining of the cavity Choroid plexus comes to the surface, i.e. the lining 3rd ventricle epindyma comes in contact with the pia mater. Choroid plexus Lateral ventricle • Blood capillaries invaginate at these regions, covered by pia and epindyma constitute the choroids plexus. • The choroid plexuses secrete the CSF into each ventricle. Choroid plexus 4th ventricleDr. Akram Jaffar Dr. Akram Jaffar
    • Blood barriers in the CNS Blood-CSF barrier • Blood-CSF barrier: – A selective barrier of substances formed by the tight junctions between the choroidal epithelial cells. • The blood brain barrier (BBB) – A selective barrier between the blood and the brain tissue. – Formed by the tight junctions BBB between the endothelial lining of the capillaries. • The function of the BBB & blood- CSF barrier is to provide a stable environment for the normal function of the CNS.Dr. Akram Jaffar Dr. Akram Jaffar
    • CSF circulation Dural venous sinus Arachnoid granulations • The CSF is produced by the choroid plexuses in all the Choroid plexus Lateral ventricle ventricles of the brain but mainly in the lateral ventricles. • Lateral ventricles  Choroid plexus 3rd ventricle interventricular foramen  3rd ventricle  cerebral aqueduct  4th ventricle. Interventricular foramen • From the 4th ventricle some CSF passes through the central Cerebral aqueduct canal of the spinal cord but the majority passes through Choroid plexus foramina in the 4th ventricle 4th ventricle which communicate with the subarachnoid space. Foramina in 4th ventricle Subarachnoid spaceDr. Akram Jaffar Dr. Akram Jaffar
    • CSF circulation • From the subarachnoid space the CSF finds its way to the venous circularion through arachnoid villi which project into the dural venous sinuses particularly the superior sagittal sinus. • Collections of arachnoid pits Arachnoid granulations villi form archnoid granulations. • arachnoid granulations produce pits on the inside of the calvaria on either side of the superior sagittal sinus.Dr. Akram Jaffar Dr. Akram Jaffar