Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download The Nervous System: The Brain and Cranial Nerves
Transcript
16 The Nervous System: The Brain and Cranial Nerves PowerPoint® Lecture Presentations prepared by Steven Bassett Southeast Community College Lincoln, Nebraska © 2012 Pearson Education, Inc. Introduction • The brain is a complex three-dimensional structure that performs a bewildering array of functions • Think of the brain as an organic computer • However, the brain is far more versatile than a computer • The brain is far more complex than the spinal cord • The brain consists of roughly 20 billion neurons © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain • Embryology of the brain • The CNS begins as a neural tube • The lumen of the tube (neurocoel) is filled with fluid • In the fourth week of development, the cephalic area of the neural tube enlarges to form: • Prosencephalon • Mesencephalon • Rhombencephalon © 2012 Pearson Education, Inc. Table 16.1 Development of the Human Brain © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain • Embryology of the brain (continued) • Prosencephalon eventually develops to form: • Telencephalon: forms the cerebrum • Diencephalon: forms the epithalamus, thalamus, and hypothalamus © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain • Mesencephalon • Does not subdivide • Becomes the midbrain • Rhombencephalon • Eventually develops to form: • Metencephalon: forms the pons and cerebellum • Myelencephalon: forms the medulla oblongata © 2012 Pearson Education, Inc. Figure 16.1 Major Divisions of the Brain Left cerebral hemisphere Gyri Sulci CEREBRUM • Conscious thought processes, intellectual functions • Memory storage and processing • Conscious and subconscious regulation of skeletal muscle contractions Fissures DIENCEPHALON THALAMUS • Relay and processing centers for sensory information HYPOTHALAMUS • Centers controlling emotions, autonomic functions, and hormone production CEREBELLUM Spinal cord MESENCEPHALON Brain stem • Processing of visual and auditory data • Generation of reflexive somatic motor responses • Maintenance of consciousness PONS • Relays sensory information to cerebellum and thalamus • Subconscious somatic and visceral motor centers © 2012 Pearson Education, Inc. MEDULLA OBLONGATA • Relays sensory information to thalamus and to other portions of the brain stem • Autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities) • Coordinates complex somatic motor patterns • Adjusts output of other somatic motor centers in brain and spinal cord An Introduction to the Organization of the Brain • Major Regions and Landmarks of the Brain • • • • • • Medulla oblongata Pons Cerebellum Mesencephalon (midbrain) Diencephalon Cerebrum (telencephalon) © 2012 Pearson Education, Inc. Figure 16.13a Sectional Views of the Brain Precentral gyrus Central sulcus Postcentral gyrus Cingulate gyrus Fornix Thalamus Membranous portion of epithalamus Hypothalamus Corpus callosum Septum pellucidum Pineal gland Interventricular foramen Parieto-occipital sulcus Superior colliculus Corpora Inferior quadrigemina colliculus Frontal lobe Anterior commissure Optic chiasm Aqueduct of midbrain Mamillary body Fourth ventricle Temporal lobe Cerebellum Mesencephalon Pons A sagittal section through the brain © 2012 Pearson Education, Inc. Medulla oblongata An Introduction to the Organization of the Brain • Medulla oblongata • Relays information to the thalamus and brain stem • Regulates visceral function • Pons • Relays information to the thalamus and cerebellum • Regulates subconscious somatic and visceral motor centers © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain • Cerebellum • Coordinates somatic motor function • Adjusts output of somatic motor centers resulting in smooth operation • Mesencephalon (midbrain) • Processes visual and auditory data • Maintains consciousness and alertness © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain • Diencephalon • Epithalamus • Contains the pineal gland • Thalamus • Relays information to the cerebrum • Processes sensory information • Hypothalamus • Involved in emotions, thirst, some habitual activity © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain • Telencephalon (cerebrum) • Conscious thought processes • Memory storage • Conscious regulation of skeletal muscle contractions © 2012 Pearson Education, Inc. Figure 16.1 Major Divisions of the Brain Left cerebral hemisphere Gyri Sulci CEREBRUM • Conscious thought processes, intellectual functions • Memory storage and processing • Conscious and subconscious regulation of skeletal muscle contractions Fissures DIENCEPHALON THALAMUS • Relay and processing centers for sensory information HYPOTHALAMUS • Centers controlling emotions, autonomic functions, and hormone production CEREBELLUM Spinal cord MESENCEPHALON Brain stem • Processing of visual and auditory data • Generation of reflexive somatic motor responses • Maintenance of consciousness PONS • Relays sensory information to cerebellum and thalamus • Subconscious somatic and visceral motor centers © 2012 Pearson Education, Inc. MEDULLA OBLONGATA • Relays sensory information to thalamus and to other portions of the brain stem • Autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities) • Coordinates complex somatic motor patterns • Adjusts output of other somatic motor centers in brain and spinal cord An Introduction to the Organization of the Brain • Gray Matter and White Matter Organization • The cerebrum consists of: • Inner region of gray matter • Surrounded by tracts of white matter • Gray matter consists of cell bodies © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain • The Ventricles of the Brain • Ventricles are fluid-filled cavities • Filled with cerebrospinal fluid (CSF) • Fluid transports nutrients to the CNS and transports waste away from the CNS • CSF also provides protection • There are four ventricles • Ventricles 1 and 2 (called lateral ventricles) are in the cerebral hemispheres (separated by a partition called the septum pellucidum) • Ventricle 3 is in the diencephalon • Ventricle 4 lies between the pons and the cerebellum © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain • Lateral ventricles (ventricles 1 and 2) • Main portion of the ventricle lies in the parietal lobes • Each has an anterior horn extending into the frontal lobe • Each has a posterior horn extending into the occipital lobe • Each has an inferior horn extending into the temporal lobe • Each communicates with the third ventricle • Through the interventricular foramen © 2012 Pearson Education, Inc. Figure 16.2a Ventricles of the Brain Cerebral hemispheres Lateral ventricles Interventricular foramen Third ventricle Anterior horns of lateral ventricles Posterior horns of lateral ventricles Inferior horns of lateral ventricles Aqueduct of midbrain Pons Medulla oblongata Central canal Spinal cord Fourth ventricle Cerebellum Orientation and extent of the ventricles as seen in a lateral view of a transparent brain © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain • Third ventricle • Communicates with the fourth ventricle • Through the aqueduct of the midbrain • Fourth ventricle • Communicates with the central canal of the spinal cord © 2012 Pearson Education, Inc. Figure 16.2a Ventricles of the Brain Cerebral hemispheres Lateral ventricles Interventricular foramen Third ventricle Anterior horns of lateral ventricles Posterior horns of lateral ventricles Inferior horns of lateral ventricles Aqueduct of midbrain Pons Medulla oblongata Central canal Spinal cord Fourth ventricle Cerebellum Orientation and extent of the ventricles as seen in a lateral view of a transparent brain © 2012 Pearson Education, Inc. Figure 16.2b Ventricles of the Brain Anterior horn of lateral ventricle Lateral ventricle (left) Inferior horns of lateral ventricles Interventricular foramen Third ventricle Aqueduct of midbrain Posterior horn of lateral ventricle Fourth ventricle Lateral view of a plastic cast of the ventricles © 2012 Pearson Education, Inc. Figure 16.2c Ventricles of the Brain Lateral ventricles in cerebral hemispheres Longitudinal fissure Interventricular foramen Third ventricle Inferior horns of lateral ventricles Aqueduct of midbrain Pons Fourth ventricle Medulla oblongata Cerebellum Central canal Anterior view of the ventricles as if seen through a transparent brain © 2012 Pearson Education, Inc. Figure 16.2d Ventricles of the Brain Lateral ventricles Interventricular foramen Third ventricle Inferior horn of lateral ventricle Aqueduct of midbrain Septum pellucidum Fourth ventricle Central canal Diagrammatic coronal section showing the interconnections between the ventricles © 2012 Pearson Education, Inc. Protection and Support of the Brain • Protection involves: • Bones of the skull • Parietal, frontal, occipital, and temporal bones • Cranial meninges • Dura mater, arachnoid mater, and pia mater • Cerebrospinal fluid • Blood–brain barrier © 2012 Pearson Education, Inc. Protection and Support of the Brain • Cranial Meninges: The Dura Mater • Consists of two layers • Endosteal layer • This is the layer felt within the anterior fontanel of a baby • Meningeal layer • Space between the two layers is called the dural sinus • The meningeal layer forms folds called: • • • • falx cerebri tentorium cerebelli falx cerebelli diaphragma sellae © 2012 Pearson Education, Inc. Protection and Support of the Brain • Folds of the Dura Mater • Falx cerebri • Meningeal layer that extends into the longitudinal fissure • Inferior/anterior portion attaches to the crista galli • Inferior/posterior portion attaches to the internal occipital crest and the tentorium cerebelli • Tentorium cerebelli • Separates the cerebellar hemispheres from the cerebral hemispheres • Extends across the cranium at right angles to the falx cerebri © 2012 Pearson Education, Inc. Protection and Support of the Brain • Folds of the Dura Mater (continued) • Falx cerebelli • Extends from the tentorium cerebelli to separate the cerebellar hemispheres • Diaphragma sellae • Lines the sella turcica of the sphenoid bone • It anchors the dura mater to the sphenoid bone • It encases the pituitary gland © 2012 Pearson Education, Inc. Figure 16.3a Relationships among the Brain, Cranium, and Meninges Cranium Dura mater (endosteal layer) Dural sinus Dura mater (meningeal layer) Subdural space Arachnoid mater Cerebral cortex Cerebral cortex Cerebellum Medulla oblongata Lateral view of the brain showing its position in the cranium and the organization of the meningeal coverings © 2012 Pearson Education, Inc. Spinal cord Pia mater Subarachnoid space Figure 16.3b Relationships among the Brain, Cranium, and Meninges Superior sagittal sinus Cranium Inferior sagittal sinus Diaphragma sellae Falx cerebri Dura mater Tentorium cerebelli Pituitary gland Sella turcica of sphenoid Transverse sinus Falx cerebelli A corresponding view of the cranial cavity with the brain removed showing the orientation and extent of the falx cerebri and tentorium cerebelli © 2012 Pearson Education, Inc. Figure 16.5a The Cranial Meninges, Part II Coronal section Superior sagittal sinus Dura mater Subdural space Arachnoid mater Arachnoid trabeculae Pia mater Arachnoid granulation Falx cerebri Subarachnoid space Cerebral cortex This view shows the organization and relationship of the cranial meninges to the brain. © 2012 Pearson Education, Inc. Protection and Support of the Brain • Cranial Meninges: The Arachnoid Mater • Consists of projections called arachnoid granulations • CSF flows through these to enter into blood circulation • Consists of weblike material underlining the arachnoid layer • These collagenous fibers help anchor cerebral blood vessels © 2012 Pearson Education, Inc. Figure 16.5b The Cranial Meninges, Part II Coronal section Arachnoid mater Arachnoid trabecula Cerebral vein Pia mater Cerebral cortex Perivascular space A detailed view of the arachnoid membrane, the subarachnoid space, and the pia mater. Note the relationship between the cerebral vein and the subarachnoid space. © 2012 Pearson Education, Inc. Protection and Support of the Brain • Cranial Meninges: The Pia Mater • Attached to the surface of the brain • Follows the sulci and gyri of the brain • Helps to anchor the larger blood vessels of the cerebrum © 2012 Pearson Education, Inc. Figure 16.4 The Cranial Meninges, Part I ANTERIOR Loose connective tissue and periosteum of cranium Cranium Dura mater Subarachnoid space Epicranial aponeurosis Arachnoid mater Scalp Cerebral cortex covered by pia mater POSTERIOR © 2012 Pearson Education, Inc. Protection and Support of the Brain • Cerebrospinal Fluid (CSF) • • • • Provides protection of the brain and spinal cord Provides support Transports nutrients to the CNS tissue Transports waste away from the CNS © 2012 Pearson Education, Inc. Protection and Support of the Brain • Formation of CSF • Produced by the ependymal cells of the choroid plexus • They actively transport nutrients, vitamins, and ions into the CSF • They actively remove waste from the CSF © 2012 Pearson Education, Inc. Figure 16.6 The Choroid Plexus and Blood–Brain Barrier INTERSTITIAL FLUID IN THALAMUS Nutrients (especially glucose) Oxygen Ependymal cells Capillary Endothelial cell Capillary Blood–brain barrier CO2 Waste products Tight junction The location of the choroid plexus in each of the four ventricles of the brain Astrocyte Choroid plexus cells Waste products Ions Amino acids (when necessary) The structure and function of the choroid plexus. The ependymal cells are a selective barrier, actively transporting nutrients, vitamins, and ions into the CSF. When necessary, these cells also actively remove ions or compounds from the CSF to stabilize its composition. © 2012 Pearson Education, Inc. Ions (Na, K, Cl, HCO3, Ca2, Mg2) Vitamins Organic nutrients Oxygen Tight junction CHOROID PLEXUS CEREBROSPINAL FLUID IN THIRD VENTRICLE Neuron Protection and Support of the Brain • Circulation of CSF • • • • • • CSF from the choroid plexus of the lateral ventricles Flows through the interventricular foramen Flows into the third ventricle Flows into the aqueduct of the midbrain Flows into the fourth ventricle Through the lateral aperture and median aperture and central canal of the spinal cord • Flows into the subarachnoid space • Flows around the brain and spinal cord eventually enters circulation via the arachnoid granulations © 2012 Pearson Education, Inc. Figure 16.7 Circulation of Cerebrospinal Fluid Superior sagittal sinus Cranium Arachnoid granulations Dura mater (endosteal layer) Arachnoid granulation Fluid movement Extension of choroid plexus into lateral ventricle Arachnoid trabecula Dura mater (meningeal layer) Cerebral cortex Superior sagittal sinus Choroid plexus of third ventricle Aqueduct of midbrain Lateral aperture Choroid plexus of fourth ventricle Median aperture Central canal Arachnoid mater Subarachnoid space Dura mater Spinal cord Filum terminale © 2012 Pearson Education, Inc. Pia mater Subarachnoid space Subdural space Arachnoid mater Protection and Support of the Brain • Blood–Brain Barrier • The lining of the blood vessels consists of endothelial cells that are highly interconnected by tight junctions • Due to this tight connection, only lipid-soluble material can pass from the blood to the cells of the brain and spinal cord • Water-soluble material can only pass via the action of transport mechanisms • The transport mechanisms are very specific © 2012 Pearson Education, Inc. The Medulla Oblongata • Medulla oblongata • Continuous with the spinal cord to the brain stem • All communication between the brain and spinal cord passes through the medulla oblongata • Nuclei in the medulla oblongata are: • Relay stations for sensory or motor pathways • Associated with cranial nerves connected to the medulla oblongata • Associated with the autonomic control of visceral organs © 2012 Pearson Education, Inc. The Medulla Oblongata • Relay stations • Nucleus gracilis and nucleus cuneatus • Pass sensory information to the thalamus • Olivary nuclei • Pass information to the cerebrum, diencephalon, and brain stem © 2012 Pearson Education, Inc. The Medulla Oblongata • Nuclei of cranial nerves • Contains sensory and motor nuclei of cranial nerves: • VIII, IX, X, XI, and XII • Autonomic nuclei • Major centers include: • Cardiovascular centers (cardiac and vasomotor) • Respiratory centers (rhythmic breathing) © 2012 Pearson Education, Inc. Figure 16.8a The Medulla Oblongata Olivary nucleus Cardiovascular centers Pons Medulla oblongata Solitary nucleus Nucleus cuneatus Olive Pyramids Nucleus gracilis Reticular formation Spinal cord Anterior view © 2012 Pearson Education, Inc. Lateral white column Figure 16.8b The Medulla Oblongata Olivary nucleus Attachment to membranous roof of fourth ventricle Cardiovascular centers Respiratory rhythmicity center Pons Solitary nucleus Nucleus cuneatus Olive Pyramids Nucleus gracilis Posterior median sulcus Reticular formation Lateral white column Spinal cord Posterolateral view © 2012 Pearson Education, Inc. Posterior white columns The Pons • The pons is a prominent bulge superior to the medulla oblongata and consists of: • Sensory and motor nuclei for cranial nerves: • V, VI, VII, and VIII • Nuclei involved with involuntary control of breathing: • Consist of apneustic center and pneumotaxic center • Nuclei that relay cerebellar commands: • Consist of cerebellar peduncles • Ascending, descending, and transverse tracts © 2012 Pearson Education, Inc. Figure 16.9 The Pons Descending tracts Ascending tracts Transverse fibers Pneumotaxic center Apneustic center Cerebellum Fourth ventricle Pons Medulla oblongata Reticular formation Olivary nucleus © 2012 Pearson Education, Inc. The Mesencephalon • Mesencephalon (also called the midbrain) • Consists of two pairs of nuclei collectively called corpora quadrigemina • Responsible for processing auditory and visual stimuli • Auditory processing occurs in the inferior colliculus • Visual processing occurs in the superior colliculus • Consists of nuclei of the reticular formation • Involved in maintaining alertness © 2012 Pearson Education, Inc. The Mesencephalon • Mesencephalon (continued) • Consists of: • Red nucleus: integrates information between the cerebrum and cerebellum • Substantia nigra: regulates motor output of the basal nuclei • Cerebral peduncles: have ascending fibers that synapse in the thalamus and descending fibers of the corticospinal pathway © 2012 Pearson Education, Inc. Figure 16.10b The Mesencephalon Thalamus Superior colliculi Pineal gland Substantia nigra Superior colliculus Red nucleus Cerebral peduncle Inferior colliculus Reticular formation Corpora quadrigemina Trochlear nerve (N IV) Cerebral peduncle Superior cerebellar peduncle Diagrammatic and posterior views of the diencephalon and brain stem. The diagrammatic view is drawn, as if transparent, to show the positions of important nuclei. © 2012 Pearson Education, Inc. Inferior colliculi Reticular formation in floor of fourth ventricle Fourth ventricle The Diencephalon • The diencephalon consists of: • Epithalamus • Thalamus • Hypothalamus © 2012 Pearson Education, Inc. Figure 16.12a The Hypothalamus Parietal lobe Corpus callosum Septum pellucidum Choroid plexus in epithalamus Fornix Thalamus (surrounds third ventricle) Anterior cerebral artery Pineal gland Hypothalamus Frontal lobe Aqueduct of midbrain Anterior commissure Cerebellum Fourth ventricle Optic chiasm Optic Infundibulum Tuberal area (cut) nerve Mamillary body Midsagittal section through the brain. This view shows the major features of the diencephalon and adjacent portions of the brain stem. © 2012 Pearson Education, Inc. The Diencephalon • The epithalamus • Forms the roof of the third ventricle • Contains the pineal gland • Produces the hormone melatonin • Regulates our day/night cycles © 2012 Pearson Education, Inc. The Diencephalon • The thalamus • • • • Forms the walls of the third ventricle There is a right and a left thalamus Thalamic nuclei are egg-shaped Each thalamic nucleus is divided into: • Anterior group: part of the limbic system • Medial group: relays information to the frontal lobe • Ventral group: relays information to the parietal lobes • Posterior group: relays information to the occipital lobe • Lateral group: adjusts activity in the cingulate gyrus © 2012 Pearson Education, Inc. Figure 16.11a The Thalamus Frontal lobe Parietal lobe Occipital lobe Lateral view of the brain showing the positions of the major thalamic structures. Functional areas of cerebral cortex are also indicated, with colors corresponding to those of the associated thalamic nuclei. © 2012 Pearson Education, Inc. Figure 16.11b The Thalamus Limbic system Frontal lobes Anterior group Parietal lobe and cingulate gyrus Association areas of cerebral cortex Medial group Lateral group Posterior group V e n t r a l g r o u p Pulvinar Auditory input Medial geniculate nucleus Basal nuclei Cerebellum General sensory input Visual input Lateral geniculate nucleus Enlarged view of the thalamic nuclei of the left side. The color of each nucleus or group of nuclei matches the color of the associated cortical region. The boxes either provide examples of the types of sensory input relayed to the basal nuclei and cerebral cortex or indicate the existence of important feedback loops involved with emotional states, learning, and memory. © 2012 Pearson Education, Inc. Table 16.5 The Thalamus © 2012 Pearson Education, Inc. The Diencephalon • The hypothalamus • Forms the floor of the third ventricle • Consists of numerous nuclei • Consists of an infundibulum, which connects to the pituitary gland • Consists of the mamillary body on the posterior wall of the hypothalamus © 2012 Pearson Education, Inc. The Diencephalon • The hypothalamus (continued) • Consists of nuclei to control: • Subconscious control of skeletal muscles • Heart rate, blood pressure, respiration, and digestive functions • Secretion of antidiuretic hormone and oxytocin • Emotional and behavioral drives and thirst drives • Coordination between voluntary and autonomic functions • Body temperature • Circadian rhythm © 2012 Pearson Education, Inc. Figure 16.12a The Hypothalamus Parietal lobe Corpus callosum Septum pellucidum Choroid plexus in epithalamus Fornix Thalamus (surrounds third ventricle) Anterior cerebral artery Pineal gland Hypothalamus Frontal lobe Aqueduct of midbrain Anterior commissure Cerebellum Fourth ventricle Optic chiasm Optic Infundibulum Tuberal area (cut) nerve Mamillary body Midsagittal section through the brain. This view shows the major features of the diencephalon and adjacent portions of the brain stem. © 2012 Pearson Education, Inc. Figure 16.12b The Hypothalamus Autonomic centers (sympathetic) Paraventricular nucleus Thalamus Preoptic area Hypothalamus Autonomic centers (parasympathetic) Suprachiasmatic nucleus Supraoptic nucleus Tuberal nuclei Optic chiasm Infundibulum Anterior lobe of pituitary gland Pars distalis Pars intermedia Tuberal area Mamillary body Posterior lobe of pituitary gland (pars nervosa) Pons Enlarged view of the hypothalamus showing the locations of major nuclei and centers. Functions for these centers are summarized in Table 16.6. © 2012 Pearson Education, Inc. The Cerebellum • The cerebellum consists of: • • • • • • • Two hemispheres Folia (folds similar to gyri of the cerebrum) Anterior and posterior lobes Vermis (separates the hemispheres) Flocculonodular lobes Arbor vitae Cerebellar peduncles © 2012 Pearson Education, Inc. Figure 16.15b The Cerebellum Dendrites projecting into the gray matter of the cerebellum Cell body of Purkinje cell Axons of Purkinje cells projecting into the white matter of the cerebellum Purkinje cells LM 120 Superior colliculus Aqueduct of midbrain Mamillary body Mesencephalon Inferior colliculus Anterior lobe Anterior lobe Arbor vitae Pons Arbor vitae Cerebellar nucleus Cerebellar cortex Cerebellar peduncles Superior Middle Inferior Medulla oblongata Cerebellar cortex Pons Posterior lobe Fourth ventricle Choroid plexus of the fourth ventricle Medulla oblongata Flocculonodular lobe Sagittal view of the cerebellum showing the arrangement of gray matter and white matter. Purkinje cells are seen in the photomicrograph; these large neurons are found in the cerebellar cortex. © 2012 Pearson Education, Inc. Cerebellar nucleus Posterior lobe Flocculonodular lobe Figure 16.15a The Cerebellum Cerebellum Vermis Vermis Anterior lobe Primary fissure Posterior lobe Folia Folia Left hemisphere of cerebellum Right hemisphere of cerebellum Superior surface of the cerebellum. This view shows major anatomical landmarks and regions. © 2012 Pearson Education, Inc. The Cerebellum • The cerebellum • Cerebellar cortex: subconscious coordination of movements • Arbor vitae: connects cerebellar cortex with cerebellar peduncles • Cerebellar peduncles • Superior: connect cerebellum with mesencephalon, diencephalon, and cerebrum • Middle: communicate between cerebellum and pons • Inferior: connect cerebellum with the medulla oblongata © 2012 Pearson Education, Inc. Figure 16.15b The Cerebellum Dendrites projecting into the gray matter of the cerebellum Cell body of Purkinje cell Axons of Purkinje cells projecting into the white matter of the cerebellum Purkinje cells LM 120 Superior colliculus Aqueduct of midbrain Mamillary body Mesencephalon Inferior colliculus Anterior lobe Anterior lobe Arbor vitae Pons Arbor vitae Cerebellar nucleus Cerebellar cortex Cerebellar peduncles Superior Middle Inferior Medulla oblongata Cerebellar cortex Pons Posterior lobe Fourth ventricle Choroid plexus of the fourth ventricle Medulla oblongata Flocculonodular lobe Sagittal view of the cerebellum showing the arrangement of gray matter and white matter. Purkinje cells are seen in the photomicrograph; these large neurons are found in the cerebellar cortex. © 2012 Pearson Education, Inc. Cerebellar nucleus Posterior lobe Flocculonodular lobe The Cerebrum • The cerebrum consists of: • Two hemispheres • Several lobes • Frontal, parietal, occipital, and temporal • • • • • Gyri and sulci Longitudinal fissure Corpus callosum Basal nuclei Limbic system © 2012 Pearson Education, Inc. The Cerebrum • The Cerebral Hemispheres • The hemispheres consist of: • • • • Gyri and sulci Central sulcus Longitudinal fissure Cerebral lobes © 2012 Pearson Education, Inc. Figure 16.16a The Cerebral Hemispheres, Part I ANTERIOR Longitudinal fissure Right cerebral hemisphere Left cerebral hemisphere Cerebral veins and arteries covered by arachnoid mater Central sulcus Parieto-occipital sulcus Cerebellum POSTERIOR Superior view © 2012 Pearson Education, Inc. The Cerebrum • The Cerebral Hemispheres • The Cerebral Lobes • Frontal lobe: conscious control of skeletal muscles • Occipital lobe: perception of visual stimuli • Parietal lobe: conscious perception of touch, pressure, vibration, pain, temperature, and taste • Temporal lobe: conscious perception of auditory and olfactory stimuli © 2012 Pearson Education, Inc. Figure 16.17a The Cerebral Hemispheres, Part II Precentral gyrus Postcentral gyrus PARIETAL LOBE Central sulcus FRONTAL LOBE of left cerebral hemisphere OCCIPITAL LOBE Lateral sulcus Branches of middle cerebral artery emerging from lateral sulcus TEMPORAL LOBE Cerebellum Pons Lateral view of intact brain after removal of the Medulla oblongata dura mater and arachnoid mater showing superficial surface anatomy of the left hemisphere © 2012 Pearson Education, Inc. The Cerebrum • Motor and Sensory Areas of the Cerebral Cortex • Precentral gyrus • Anterior to the central gyrus • Neurons direct voluntary movements by controlling somatic motor neurons in the brain stem and spinal cord • Postcentral gyrus • Posterior to the central gyrus • Neurons receive somatic sensory information for touch, pressure, pain, taste, and temperature from the dorsal columns and spinothalamic tracts © 2012 Pearson Education, Inc. Figure 16.13a Sectional Views of the Brain Precentral gyrus Central sulcus Postcentral gyrus Cingulate gyrus Fornix Thalamus Membranous portion of epithalamus Hypothalamus Corpus callosum Septum pellucidum Pineal gland Interventricular foramen Parieto-occipital sulcus Superior colliculus Corpora Inferior quadrigemina colliculus Frontal lobe Anterior commissure Optic chiasm Aqueduct of midbrain Mamillary body Fourth ventricle Temporal lobe Cerebellum Mesencephalon Pons A sagittal section through the brain © 2012 Pearson Education, Inc. Medulla oblongata The Cerebrum • Hemispheric Specialization • Left hemisphere • Speech center, writing, language, mathematics • Right hemisphere • Analysis by touch, spatial visualization © 2012 Pearson Education, Inc. Figure 16.18 Hemispheric Specialization RIGHT HAND LEFT HAND Prefrontal cortex Prefrontal cortex Speech center Anterior commissure C O R P U S C A L L O S U M Writing Auditory cortex (right ear) General interpretive center (language and mathematical calculation) Analysis by touch Auditory cortex (left ear) Spatial visualization and analysis Visual cortex (right visual field) Visual cortex (left visual field) LEFT HEMISPHERE © 2012 Pearson Education, Inc. RIGHT HEMISPHERE The Cerebrum • The Central White Matter • Consists of bundles called: • Association fibers: tracts that interconnect areas of neural cortex within a hemisphere (arcuate fibers and longitudinal fasciculi) • Commissural fibers: tracts that connect the two hemispheres (anterior commissure and corpus callosum) • Projection fibers: tracts that link the cerebrum with other regions of the brain and spinal cord © 2012 Pearson Education, Inc. Figure 16.19a The Central White Matter Arcuate fibers Longitudinal fasciculi Lateral aspect of the brain showing arcuate fibers and longitudinal fasciculi © 2012 Pearson Education, Inc. Figure 16.19b The Central White Matter Longitudinal fissure Corpus callosum Projection fibers of internal capsule Anterior commissure Anterior view of the brain showing orientation of the commissural and projection fibers © 2012 Pearson Education, Inc. The Cerebrum • The Basal Nuclei • These are masses of gray matter embedded in the white matter inferior to the lateral ventricles • Consist of: • • • • • Caudate nucleus Amygdaloid body Claustrum Putamen Globus pallidus © 2012 Pearson Education, Inc. The Cerebrum • The Basal Nuclei • Caudate nucleus, putamen, and globus pallidus • Control the cycles of arm and leg movements when walking • Claustrum • Plays a role in subconscious processing of visual information • Amygdaloid body • Component of the limbic system © 2012 Pearson Education, Inc. Figure 16.20c The Basal Nuclei Lateral ventricle Corpus callosum Head of caudate nucleus Septum pellucidum Internal capsule Claustrum Insula Lateral sulcus Anterior commissure Putamen Lentiform nucleus Globus pallidus Amygdaloid body © 2012 Pearson Education, Inc. Tip of inferior horn of lateral ventricle Frontal section The Cerebrum • The Limbic System • Located between the cerebrum and the diencephalon just superior to the corpus callosum • Functions: • Establishes emotional states • Links the conscious functions with the unconscious autonomic functions • Facilitates memory storage and retrieval © 2012 Pearson Education, Inc. Figure 16.21a The Limbic System Interthalamic adhesion Central sulcus Cingulate gyrus (limbic lobe) Fornix Pineal gland Corpus callosum Thalamus Hypothalamus Temporal lobe Parahippocampal gyrus (limbic lobe) Hippocampus (within dentate gyrus) Mamillary body Sagittal section through the cerebrum showing the cortical areas associated with the limbic system. The parahippocampal and dentate gyri are shown as if transparent so that deeper limbic components can be seen. © 2012 Pearson Education, Inc. The Cerebrum • The limbic system consists of: • • • • Cingulate gyrus Dentate gyrus Parahippocampal gyrus Hippocampus © 2012 Pearson Education, Inc. Figure 16.21b The Limbic System Corpus callosum Cingulate gyrus Fornix Anterior nucleus of thalamus Hypothalamic nuclei Olfactory tract Amygdaloid body Mamillary body Hippocampus (within dentate gyrus) Parahippocampal gyrus Additional details concerning the threedimensional structure of the limbic system © 2012 Pearson Education, Inc. Figure 16.21a The Limbic System Interthalamic adhesion Central sulcus Cingulate gyrus (limbic lobe) Fornix Pineal gland Corpus callosum Thalamus Hypothalamus Temporal lobe Parahippocampal gyrus (limbic lobe) Hippocampus (within dentate gyrus) Mamillary body Sagittal section through the cerebrum showing the cortical areas associated with the limbic system. The parahippocampal and dentate gyri are shown as if transparent so that deeper limbic components can be seen. © 2012 Pearson Education, Inc. The Cerebrum • The Limbic System • The fornix • Tract of white matter connecting the hippocampus with the hypothalamus • Many fornix fibers extend to the mamillary bodies • Mamillary bodies control reflex movements associated with eating © 2012 Pearson Education, Inc. The Cranial Nerves • There are 12 pairs of cranial nerves • These nerves innervate the periphery emerging from the brain (not the spinal cord) • These nerves are on the ventrolateral surface of the brain • They are numbered beginning at the anterior aspect of the brain • They are numbered CN I to CN XII © 2012 Pearson Education, Inc. Figure 16.22b Origins of the Cranial Nerves Olfactory bulb, termination of olfactory nerve (N I) Olfactory tract Optic chiasm Optic nerve (N II) Infundibulum Oculomotor nerve (N III) Trochlear nerve (N IV) Trigeminal nerve (N V) Abducens nerve (N VI) Facial nerve (N VII) Vestibulocochlear nerve (N VIII) Glossopharyngeal nerve (N IX) Vagus nerve (N X) Hypoglossal nerve (N XII) Accessory nerve (N XI) Diagrammatic inferior view of the human brain. Compare view with part (a). © 2012 Pearson Education, Inc. Figure 16.22a Origins of the Cranial Nerves Olfactory bulb, termination of olfactory nerve (N I) Olfactory tract Mamillary body Optic chiasm Optic nerve (N II) Basilar artery Infundibulum Pons Oculomotor nerve (N III) Trochlear nerve (N IV) Trigeminal nerve (N V) Abducens nerve (N VI) Facial nerve (N VII) Vestibulocochlear nerve (N VIII) Glossopharyngeal nerve (N IX) Vertebral artery Vagus nerve (N X) Cerebellum Hypoglossal nerve (N XII) Medulla oblongata Accessory nerve (N XI) Spinal cord The inferior surface of the brain as it appears on gross dissection. The roots of the cranial nerves are clearly visible. © 2012 Pearson Education, Inc. The Cranial Nerves • CN I: The Olfactory Nerve • • • • Function: sensory (smell) Origin: olfactory epithelium Foramen: olfactory foramina Destination: olfactory bulbs © 2012 Pearson Education, Inc. Figure 16.23 The Olfactory Nerve Left olfactory bulb (termination of olfactory nerve) Olfactory tract (to olfactory cortex of cerebrum) OLFACTORY NERVE (N I) Cribriform plate of ethmoid Olfactory epithelium © 2012 Pearson Education, Inc. Olfactory nerve fibers The Cranial Nerves • CN II: The Optic Nerve • • • • Function: sensory (vision) Origin: retina Foramen: optic canal Destination: diencephalon, then to occipital lobe © 2012 Pearson Education, Inc. Figure 16.24 The Optic Nerve Eye Olfactory bulb Olfactory tract OPTIC NERVE (N II) Optic chiasm Pituitary gland Optic tract Mesencephalon (cut) Lateral geniculate nucleus (in thalamus) Optic projection fibers Visual cortex (in occipital lobes) © 2012 Pearson Education, Inc. The Cranial Nerves • CN III: The Oculomotor Nerve • Function: controls extra-ocular eye muscles • • • • Motor function Superior, inferior, and medial rectus Inferior oblique Levator palpebrae superioris • Origin: mesencephalon • Foramen: superior orbital fissure • Destination: extra-ocular eye muscles © 2012 Pearson Education, Inc. Figure 16.25 Cranial Nerves Controlling the Extra–Ocular Muscles Superior oblique muscle Superior rectus muscle OPTIC NERVE (N II) Optic chiasm OCULOMOTOR NERVE (N III) TROCHLEAR NERVE (N IV) Trochlea Levator palpebrae superioris muscle Trigeminal nerve (N V), cut Inferior oblique muscle Vestibulocochlear nerve (N VIII), cut Inferior rectus muscle © 2012 Pearson Education, Inc. Ciliary ganglion Medial rectus muscle Facial nerve (N VII), cut Lateral rectus muscle (cut) ABDUCENS NERVE (N VI) The Cranial Nerves • CN IV: The Trochlear Nerve • Function: controls extra-ocular eye muscles • Motor function • Superior oblique • Origin: mesencephalon • Foramen: superior orbital fissure • Destination: extra-ocular eye muscles © 2012 Pearson Education, Inc. Figure 16.25 Cranial Nerves Controlling the Extra–Ocular Muscles Superior oblique muscle Superior rectus muscle OPTIC NERVE (N II) Optic chiasm OCULOMOTOR NERVE (N III) TROCHLEAR NERVE (N IV) Trochlea Levator palpebrae superioris muscle Trigeminal nerve (N V), cut Inferior oblique muscle Vestibulocochlear nerve (N VIII), cut Inferior rectus muscle © 2012 Pearson Education, Inc. Ciliary ganglion Medial rectus muscle Facial nerve (N VII), cut Lateral rectus muscle (cut) ABDUCENS NERVE (N VI) The Cranial Nerves • CN V: The Trigeminal Nerve • Function: • Mixed (sensory and motor) function • Ophthalmic: sensations from the forehead, eyelids, and nose • Maxillary: sensations from lower eyelid, upper lip, and cheek • Mandibular: controls mastication • Origin: ophthalmic, maxillary, and mandibular nerves © 2012 Pearson Education, Inc. The Cranial Nerves • CN V: The Trigeminal Nerve (continued) • Foramen: • Ophthalmic: superior orbital fissure • Maxillary: foramen rotundum • Mandibular: foramen ovale • Destination: • Ophthalmic and maxillary: Pons • Mandibular: mandibular muscles © 2012 Pearson Education, Inc. Figure 16.26 The Trigeminal Nerve Superior orbital Ophthalmic Semilunar fissure branch ganglion Supraorbital nerves Ciliary ganglion Foramen rotundum Infra-orbital nerve Pons TRIGEMINAL NERVE (N V) Maxillary branch Foramen ovale Lingual nerve Submandibular ganglion Mental nerve © 2012 Pearson Education, Inc. Otic ganglion Mandibular branch Pterygopalatine ganglion The Cranial Nerves • CN VI: The Abducens Nerve • Function: controls eye movements • Motor function • Origin: pons • Foramen: superior orbital fissure • Destination: innervates the lateral rectus eye muscle © 2012 Pearson Education, Inc. Figure 16.25 Cranial Nerves Controlling the Extra–Ocular Muscles Superior oblique muscle Superior rectus muscle OPTIC NERVE (N II) Optic chiasm OCULOMOTOR NERVE (N III) TROCHLEAR NERVE (N IV) Trochlea Levator palpebrae superioris muscle Trigeminal nerve (N V), cut Inferior oblique muscle Vestibulocochlear nerve (N VIII), cut Inferior rectus muscle © 2012 Pearson Education, Inc. Ciliary ganglion Medial rectus muscle Facial nerve (N VII), cut Lateral rectus muscle (cut) ABDUCENS NERVE (N VI) The Cranial Nerves • CN VII: The Facial Nerve • Function: Mixed (sensory and motor) • Sensory: sensations from the face / taste • Motor: controls muscles of the face • Origin: • Sensory: taste buds • Motor: pons • Foramen: internal acoustic meatus • Destination: • Sensory: pons • Motor: muscles of the face © 2012 Pearson Education, Inc. Figure 16.27a The Facial Nerve Pterygopalatine ganglion Greater petrosal nerve Geniculate ganglion FACIAL NERVE (N VII) Temporal branch Pons Zygomatic branches Posterior auricular branch Stylomastoid foramen Buccal branch Chorda tympani nerve (with mandibular branch of N V) Mandibular branch Lingual branch (with lingual nerve of N V) Cervical branch Origin and branches of the facial nerve © 2012 Pearson Education, Inc. Submandibular ganglion The Cranial Nerves • CN VIII: The Vestibulocochlear Nerve • Function: • Sensory: balance and hearing • Origin: receptors of the vestibule and cochlea • Foramen: internal acoustic meatus • Destination: pons © 2012 Pearson Education, Inc. Figure 16.28 The Vestibulocochlear Nerve Tympanic cavity (middle ear) Semicircular canals Vestibular branch (N VIII) Facial nerve (N VII), cut Internal acoustic canal VESTIBULOCOCHLEAR NERVE (N VIII) NV Pons N VI N VII Medulla oblongata Tympanic membrane © 2012 Pearson Education, Inc. Auditory tube Cochlea Cochlear branch (N VIII) N IX N XII NX N XI The Cranial Nerves • CN IX: The Glossopharyngeal Nerve • Function: Mixed (sensory and motor) • Sensory function: tongue pain • Motor function: swallowing • Origin: • Sensory: posterior 1/3 of the tongue • Motor: salivary gland © 2012 Pearson Education, Inc. The Cranial Nerves • CN IX: The Glossopharyngeal Nerve (continued) • Foramen: jugular foramen • Destination: • Sensory: pons • Visceral motor: parotid salivary gland • Somatic motor: pharyngeal muscles for swallowing © 2012 Pearson Education, Inc. Figure 16.29 The Glossopharyngeal Nerve Pons NV N VII N VIII N VI GLOSSOPHARYNGEAL NERVE (N IX) Otic ganglion Medulla oblongata Inferior (petrosal) ganglion Superior (jugular) ganglion Lingual branch Pharyngeal branches Parotid salivary gland Carotid sinus branch Carotid body Carotid sinus Common carotid artery © 2012 Pearson Education, Inc. The Cranial Nerves • CN X: The Vagus Nerve • Function: • Sensory: information from organs • Motor: sends information to the organs • Origin: • Sensory: from the organs • Motor: medulla oblongata © 2012 Pearson Education, Inc. The Cranial Nerves • CN X: The Vagus Nerve (continued) • Foramen: jugular foramen • Destination: • Sensory: autonomic centers of the medulla oblongata • Somatic motor: muscles of the palate and pharynx • Visceral motor: respiratory, cardiovascular, and digestive organs © 2012 Pearson Education, Inc. Figure 16.30 The Vagus Nerve VAGUS NERVE (N X) Superior pharyngeal branch Medulla oblongata Auricular branch to external ear Inferior ganglion of vagus nerve Superior ganglion of vagus nerve Pharyngeal branch Superior laryngeal nerve Superior laryngeal nerve Internal branch External branch Cardiac branches Recurrent laryngeal nerve Cardiac plexus Left lung Right lung Liver Anterior vagal trunk Stomach Pancreas Spleen Celiac plexus Colon Small intestine Hypogastric plexus © 2012 Pearson Education, Inc. The Cranial Nerves • CN XI: The Accessory Nerve • Function: • Motor: controls the sternocleidomastoid, trapezius, palate, pharynx, and larynx muscles • Origin: spinal cord and medulla oblongata • Foramen: jugular foramen • Destination: • Internal branch: muscles of the palate, pharynx, and larynx • External branch: sternocleidomastoid and trapezius muscles © 2012 Pearson Education, Inc. Figure 16.31 The Accessory and Hypoglossal Nerves HYPOGLOSSAL NERVE (N XII) ACCESSORY NERVE (N XI) Internal branch: to palatal, pharyngeal, and laryngeal muscles with vagus nerve Intrinsic muscles of tongue Trigeminal nerve (N V) Medulla oblongata Cranial root of N XI Spinal root of N XI Styloglossus muscle External branch of N XI Genioglossus muscle Geniohyoid muscle Spinal cord Hyoglossus muscle Hyoid bone Thyrohyoid muscle Trapezius muscle Sternocleidomastoid muscle Sternohyoid muscle Sternothyroid muscle Ansa cervicalis (cervical plexus) Omohyoid muscle © 2012 Pearson Education, Inc. The Cranial Nerves • CN XII: The Hypoglossal Nerve • Function: • Motor: controls tongue movement • Origin: medulla oblongata • Foramen: hypoglossal canal • Destination: tongue muscles © 2012 Pearson Education, Inc. Figure 16.31 The Accessory and Hypoglossal Nerves HYPOGLOSSAL NERVE (N XII) ACCESSORY NERVE (N XI) Internal branch: to palatal, pharyngeal, and laryngeal muscles with vagus nerve Intrinsic muscles of tongue Trigeminal nerve (N V) Medulla oblongata Cranial root of N XI Spinal root of N XI Styloglossus muscle External branch of N XI Genioglossus muscle Geniohyoid muscle Spinal cord Hyoglossus muscle Hyoid bone Thyrohyoid muscle Trapezius muscle Sternocleidomastoid muscle Sternohyoid muscle Sternothyroid muscle Ansa cervicalis (cervical plexus) Omohyoid muscle © 2012 Pearson Education, Inc. The Cranial Nerves • Summary of Cranial Nerve Branches and Functions • Mnemonic aid • Oh, Once One Takes The Anatomy Final, Very Good Vacations Are Heavenly © 2012 Pearson Education, Inc. Table 16.12 The Cranial Nerves (Part 1 of 2) © 2012 Pearson Education, Inc. Table 16.12 The Cranial Nerves (Part 2 of 2) © 2012 Pearson Education, Inc.
