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M555 Medical Neuroscience Lab 1: Gross Anatomy of Brain, Crainal Nerves and Cerebral Blood Vessels Anatomical Directions Terms like “dorsal,” “ventral,” “anterior” and “posterior” provide a means of locating structures relative to the overall orientation of the nervous system. Complications with those terms mayarise for two reasons: i) humans stand upright ii) the CNS curves or flexes as it grows from the embryonic neural tube, and the forebrain structures (telencephalon and diencephalon) are oriented somewhat differently than the brain stem (midbrain, pons, medulla, cerebellum) and spinal cord. This drawing shows the application of these terms to the human central nervous system. Forebrain Orientation telencephalon diencephalon dorsal superior rostral anterior caudal posterior dorsal rostral caudal ventral midbrain pons ventral inferior medulla cerebellum ventral dorsal rostral ventral Brain Stem and Spinal Cord Orientation spinal cord rostral superior ventral anterior dorsal caudal dorsal posterior caudal inferior Axis of CNS gross neuroanatomical structures and spaces forebrain telencephalon frontal lobe parietal lobe temporal lobe occipital lobe limbic lobe insula lateral sulcus central sulcus in the frontal lobe precentral gyrus spaces containing cerebrospinal fluid lateral ventricles interventricular foramina (cerebral) aqueduct third ventricle fourth ventricle central canal (in spinal cord) anterior commissure lamina terminalis arachnoid granulations (arachnoid villi) forebrain diencephalon pineal medial surface of the thalamus medial surface of the hypothalamus mammillary bodies in the temporal lobe superior temporal gyrus brain stem transverse gyri parahippocampal gyrus mesencephalon tectum uncus superior and inferior colliculi (corpora quadregemina) in the parietal lobe tegmentum postcentral gyrus substantia nigra angular gyrus cerebral peduncles supramarginal gyrus pons pontine nuclei between the parietal middle cerebellar peduncle and occipital lobes tegmentum parieto-occipital sulcus medulla obex in the occipital lobe location of dorsal column nuclei calcarine gyrus upper parts of dorsal columns tegmentum in the limbic lobe olives and inferior olivary nuclei cingulate gyrus pyramids corpus callosum genu, body, splenium meninges dura mater arachnoid and pia mater (leptomeniges) cerebellum lateral hemispheres tonsils vermis cranial nerves II – XII olfactory bulbs and olfactory tracts optic nerves, optic chiasm and optic tracts arteries internal carotid As anterior, middle and posterior cerebral As communicating arteries superior cerebellar A, AICA and PICA basilar artery vestibular arteries regions of cerebral cortex supplied by anterior, middle and posterior cerebral arteries see next page ... Blood Supply to the Cerebral Cortex Three major arteries - the Anterior, Middle and Posterior Cerebral Arteries supply the forebrain. Below are three views of the cerebral hemispheres. On the drawings, identify the regions supplied by these three major arteries. anterior Lateral Surface of Right Cerebral Hemisphere anterior Medial Surface of Left Cerebral Hemisphere anterior lateral Inferior Surface of Right Cerebral Hemisphere Cerebrovascular System Two systems of arterial blood flow supply the CNS. - the Internal Carotid System - the Vertebrobasilar System Internal Carotid System Find the remaining part of the Internal Carotid Arteries at the base of the brain. Anterior Cerebral Artery Anterior Communicating Artery Middle Cerebral Artery Posterior Cerebral Artery Posterior Communicating Artery Vertebrobasilar System Look for the Vertebral Arteries on the brain stem. Several smaller arteries branch from the vertebral arteries. Anterior and Posterior Spinal Arteries and the Posterior Inferior Cerebellar Arteries. Blood from the vertebral arteries enters the basilar artery. Basilar Artery is found on the ventral surface of the pons, part of the brain stem. From the basilar artery, blood distributes to several smaller arteries: anterior communicating A Superior Cerebellar Artery. Anterior Inferior Cerebellar Artery (AICA). Posterior Communicating Artery (PICA) anterior cerebral A middle cerebral A circle of Willis internal carotid A posterior communicating A posterior cerebral A superior cerebellar A anterior inferior cerebellar A posterior inferior cerebellar A vertebral A Circle of Willis A network of arteries in the vicinity of the optic chiasm forms an interconnecting network of vessels. Blood enters the Circle of Willis from both the Internal Carotid and Vertebrobasilar Systems. MRIs Horizontal Views medulla (top row) pyramids (approx location) olive (approx location) inferior cerebellar peduncle (approx location) fourth ventricle cerebellum vermis cerebellar hemispheres pons pontine nuclei (approx location) vertebral artieries and basilar artery insula Sagittal Views prime panel: bottom row, left-hand column corpus callosum – splenium, body and genu cingulate gyrus and cingulate sulcus parieto-occipital sulcus calcarine sulcus lamina terminalis thalamus and hypothalamus mammillary body brain stem – medulla, pons and midbrain tectum: superior and inferior colliculi tegmentum pontine nuclei (location) cerebellar tonsil lateral ventricle, third ventricle, cerebral aqeduct and fourth ventricle cervical spinal cord Coronal Views lateral ventricles and third ventricle temporal lobe (and uncus) cingulate gyrus corpus callosum cerebellum - vermis and hemispheres insula