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Biology 218 – Human Anatomy Session: Section: Days / Time: Instructor: Lecture Outline Adapted from Martini Human Anatomy 7th ed. FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL Chapter 16 The Nervous System The Brain and Cranial Nerves 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 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 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 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 An Introduction to the Organization of the Brain Major Regions and Landmarks of the Brain Medulla oblongata Pons Cerebellum Mesencephalon (midbrain) Diencephalon Cerebrum (telencephalon) An Introduction to the Organization of the Brain Medulla oblongata Relays information to the thalamus and brain stem © 2012 Pearson Education, Inc. Page 1 of 12 840954120 Biology 218 – Human Anatomy Session: Section: Days / Time: Instructor: Lecture Outline Adapted from Martini Human Anatomy 7th ed. FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL Regulates visceral function Pons Relays information to the thalamus and cerebellum Regulates subconscious somatic and visceral motor centers 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 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 An Introduction to the Organization of the Brain Telencephalon (cerebrum) Conscious thought processes Memory storage Conscious regulation of skeletal muscle contractions 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 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. Page 2 of 12 840954120 Biology 218 – Human Anatomy Session: Section: Days / Time: Instructor: Lecture Outline Adapted from Martini Human Anatomy 7th ed. FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL 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 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 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 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 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. Page 3 of 12 840954120 Biology 218 – Human Anatomy Session: Section: Days / Time: Instructor: Lecture Outline Adapted from Martini Human Anatomy 7th ed. FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL 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 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 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 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 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 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. Page 4 of 12 840954120 Biology 218 – Human Anatomy Session: Section: Days / Time: Instructor: Lecture Outline Adapted from Martini Human Anatomy 7th ed. FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL 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 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 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 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) 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 The Mesencephalon Mesencephalon (also called the midbrain) Consists of two pairs of nuclei collectively called corpora quadrigemina © 2012 Pearson Education, Inc. Page 5 of 12 840954120 Biology 218 – Human Anatomy Session: Section: Days / Time: Instructor: Lecture Outline Adapted from Martini Human Anatomy 7th ed. FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL 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 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 The Diencephalon The diencephalon consists of: Epithalamus Thalamus Hypothalamus The Diencephalon The epithalamus Forms the roof of the third ventricle Contains the pineal gland Produces the hormone melatonin Regulates our day/night cycles 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 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 The Diencephalon © 2012 Pearson Education, Inc. Page 6 of 12 840954120 Biology 218 – Human Anatomy Lecture Outline Adapted from Martini Human Anatomy 7th ed. Session: Section: Days / Time: Instructor: FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL 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 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 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 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 The Cerebrum The Cerebral Hemispheres The hemispheres consist of: Gyri and sulci Central sulcus Longitudinal fissure Cerebral lobes © 2012 Pearson Education, Inc. Page 7 of 12 840954120 Biology 218 – Human Anatomy Lecture Outline Adapted from Martini Human Anatomy 7th ed. Session: Section: Days / Time: Instructor: FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL 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 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 The Cerebrum Hemispheric Specialization Left hemisphere Speech center, writing, language, mathematics Right hemisphere Analysis by touch, spatial visualization 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 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 The Cerebrum The Basal Nuclei Caudate nucleus, putamen, and globus pallidus © 2012 Pearson Education, Inc. Page 8 of 12 840954120 Biology 218 – Human Anatomy Lecture Outline Adapted from Martini Human Anatomy 7th ed. Session: Section: Days / Time: Instructor: FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL 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 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 The Cerebrum The limbic system consists of: Cingulate gyrus Dentate gyrus Parahippocampal gyrus Hippocampus 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 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 The Cranial Nerves CN I: The Olfactory Nerve Function: sensory (smell) Origin: olfactory epithelium Foramen: olfactory foramina Destination: olfactory bulbs The Cranial Nerves CN II: The Optic Nerve Function: sensory (vision) Origin: retina Foramen: optic canal © 2012 Pearson Education, Inc. Page 9 of 12 840954120 Biology 218 – Human Anatomy Session: Section: Days / Time: Instructor: Lecture Outline Adapted from Martini Human Anatomy 7th ed. FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL Destination: diencephalon, then to occipital lobe 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 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 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 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 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. Page 10 of 12 840954120 Biology 218 – Human Anatomy Session: Section: Days / Time: Instructor: Lecture Outline Adapted from Martini Human Anatomy 7th ed. FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL 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 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 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 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 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. Page 11 of 12 840954120 Biology 218 – Human Anatomy Lecture Outline Adapted from Martini Human Anatomy 7th ed. Session: Section: Days / Time: Instructor: FALL 52999 MW 5:00 PM – 9:20 PM RIDDELL 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 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 The Cranial Nerves CN XII: The Hypoglossal Nerve Function: Motor: controls tongue movement Origin: medulla oblongata Foramen: hypoglossal canal Destination: tongue muscles 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. 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