* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Slides - gserianne.com
Neuroinformatics wikipedia , lookup
Intracranial pressure wikipedia , lookup
Neurolinguistics wikipedia , lookup
Synaptic gating wikipedia , lookup
Limbic system wikipedia , lookup
Lateralization of brain function wikipedia , lookup
Development of the nervous system wikipedia , lookup
Proprioception wikipedia , lookup
Central pattern generator wikipedia , lookup
Haemodynamic response wikipedia , lookup
Embodied cognitive science wikipedia , lookup
Brain morphometry wikipedia , lookup
Embodied language processing wikipedia , lookup
Selfish brain theory wikipedia , lookup
Neuroesthetics wikipedia , lookup
Environmental enrichment wikipedia , lookup
Neuroeconomics wikipedia , lookup
Sensory substitution wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Neuropsychology wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Brain Rules wikipedia , lookup
Sports-related traumatic brain injury wikipedia , lookup
Cognitive neuroscience wikipedia , lookup
Time perception wikipedia , lookup
Metastability in the brain wikipedia , lookup
History of neuroimaging wikipedia , lookup
Neural correlates of consciousness wikipedia , lookup
Neuroanatomy wikipedia , lookup
Cognitive neuroscience of music wikipedia , lookup
Neuroplasticity wikipedia , lookup
Human brain wikipedia , lookup
Anatomy of the cerebellum wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Aging brain wikipedia , lookup
Evoked potential wikipedia , lookup
Marieb’s Human Anatomy and Physiology Ninth Edition Marieb w Hoehn Chapter 12 The Central Nervous System Lecture 19 1 Lecture Overview • The brain – – – – – – Overview Protection Meninges Ventricles and the CSF The structure of the major parts of the brain Functional areas of the brain • The spinal cord – Spinal meninges, and spinal reflexes – Ascending and descending spinal tracts 2 Divisions of the Nervous System You are here CNS PNS 3 Brain – Embryology & Overview Table & Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 4 Overview of the Brain Functions • regulates visceral activities • coordinates muscular movements • interprets sensations • determines perception • stores memory • carries out reasoning • makes decisions • determines personality Major Parts • cerebrum (two hemispheres) • diencephalon • thalamus • hypothalamus • brain stem • midbrain (mesencephalon) • pons • medulla oblongata • cerebellum 5 Protection of the Brain • The brain is protected – Mechanically by • The skull bones • The meninges • The cerebrospinal (CSF) fluid – Biochemically by the blood-brain barrier • Capillaries interconnected by tight junctions • Astrocytes/ependymal cells control permeability of general capillaries/choroid capillaries • May be obstacle to delivery of drugs • May become more permeable during stress 6 Meninges of the Brain - dura mater – outer, tough (anchoring dural folds) - Subdural space – like interstitial fluid - arachnoid mater – web-like *Singular of meninges is meninx - Subarachnoid space – CSF - pia mater – inner, delicate Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 7 Dural Folds Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 Falx Cerebri – within longitudinal fissure; separates cerebral hemispheres Tentorium Cerebelli – above cerebellum; separates occipital lobe from cerebellum 8 Ventricles of the Brain • interconnected cavities • within cerebral hemispheres and brain stem • continuous with central canal of spinal cord • filled with cerebrospinal fluid (CSF) • lateral ventricles (1, 2) • third ventricle (3) • fourth ventricle (4) • cerebral aqueduct 9 Cerebrospinal Fluid • secreted by choroid plexus of ventricles (~500 ml/day) • circulates in ventricles, central canal of spinal cord, and subarachnoid space • completely surrounds brain and spinal cord • clear liquid (more Na+ and Cl-, but less K+, Ca2+, glucose, and protein than plasma) • nutritive and protective • helps maintain stable ion concentrations in CNS 10 Flow of CSF (Monro) (Luscka) (Magendie) Know Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 11 Overview of the Cerebrum of the Brain Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 -Over 85% of brain mass, with about 14 billion multipolar neurons in cortex - Lobes named for overlying bones. (See sulci above for divisions) 12 Functions of Cerebrum • interpretation • initiating voluntary movements • storing memory • retrieving memory • reasoning • center for intelligence and personality The cerebrum can be divided into several functional areas: - Motor (frontal cortex) - Sensory (parietal, occipital, and temporal cortex) - Association (all lobes) Points to keep in mind: - Each cerebral hemisphere receives information from, and sends information to, the opposite side of the body - Although symmetrical, the cerebral hemispheres are not entirely equal in function 13 Brain – Sensory and Motor Areas * 4 6 1 5 8 7 2 9 3 40 (Gnostic) 44 39 10 43 42 41 22 18 19 17 Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 *Somatosensory = Somesthetic 14 Cerebral Cortex Motor/Sensory Homunculi Notice the relative amount of cortical tissue devoted to each sensory function. 15 Hemispheric (Cerebral) Lateralization Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Categorical hemisphere Representational hemisphere 16 Basal Nuclei (formerly basal ganglia) • nuclei are masses of gray matter in CNS • deep within cerebral hemispheres • three nuclei: caudate nucleus and putamen, (together called the striatum), and the globus pallidus • subconscious control certain muscular activities, e.g., learned movement patterns 1. Receive input from entire cerebral cortex. 2. Relay motor impulses originating in the substantia nigra (where is this?), along with their own output, through the thalamus to the motor cortex to influence muscle movement. 17 Brain – Cerebral White Matter Three types of myelinated tracts form cerebral white matter: 1. Association – same hemisphere 2. Commisural – between corresponding gyri in opposite hemispheres 3. Projection – Ascending and descending tracts 18 Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 Basal Nuclei • nuclei are masses of gray matter in CNS • deep within cerebral hemispheres • caudate nucleus, putamen, globus pallidus (together called the corpus striatum) • subconscious control certain muscular activities, e.g., learned movement patterns Relay motor impulses originating in the cerebral cortex and substantia nigra of the midbrain. 19 Limbic System Consists of • portions of frontal lobe • portions of temporal lobe • hypothalamus • thalamus • basal nuclei • other deep nuclei • associated with sense of smell (less significant) Functions • controls emotions • produces feelings • interprets sensory impulses • facilitates memory storage and retrieval (learning!) The motivational system Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 20 Memory • A “Memory” is the persistence of knowledge that can be accessed (we hope!) at a later time. • Memories are not stored in individual “memory cells” or neurons; they are stored as pathways called engrams, or memory traces that use strengthened or altered synapses. • Immediate memory lasts a few seconds, e.g., remembering the earliest part of a sentence to make sense of it. • Short-term memory (STM) lasts a few seconds to a few hours – Working memory is a form of this (repeating a phone number over to yourself just long enough to dial it – and then forget it!) – Limited to a few ‘bits’ of information (about 7-9). So, ‘chunk up’! • Long-term memory (LTM) can last a lifetime – Can hold much more information that STM – Declarative (events and facts) – Procedural (motor skills) 21 Diencephalon • between cerebral hemispheres and brainstem • surrounds third ventricle • thalamus • hypothalamus • epithalamus (Tectum) • optic tracts • optic chiasm • infundibulum • posterior pituitary • mammillary bodies • pineal gland 22 Diencephalon - Thalamus Ventral nuclei - Posterior; relay for taste - Anterior and Lateral; voluntary motor - Forms wall of third ventricle - Crude interpretation center for pain, touch, pressure, temperature Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 Relay for hearing Relay for vision The ‘gateway’ to the cerebral cortex. Major relay for sensory information coming into the cerebral cortex, roles in cortical arousal, learning, and memory 23 Diencephalon - Hypothalamus Hypothalamus - maintains homeostasis by regulating visceral activities (see list below for examples…) - Heart rate and blood pressure - Body temperature - Stimulation of the pituitary (links nervous and endocrine) - Water balance (ADH) - SM contraction (OT) - Feeding/satiety centers - Movement/secretions of glands and intestines - Sleep and wakefulness - Rage/aggression - Psychosomatic illness Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 24 Brain Stem Three Parts 1. Midbrain 2. Pons 3. Medulla Oblongata (Tectum) 25 Brain Stem Three Parts 1. Midbrain 2. Pons 3. Medulla Oblongata (Tectum) 26 Midbrain • between diencephalon and pons • contains bundles of fibers that join lower parts of brainstem and spinal cord with higher part of brain Major connecting center between spinal cord and brain and parts of brainstem (Tectum) • cerebral aqueduct • cerebral peduncles – bundles of nerve fibers • contains red nucleus (rubro-) and substantia nigra • corpora quadrigemina – centers for visual and auditory reflexes Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 Origins of: CN III, IV 27 Pons • rounded bulge on underside of brainstem • between medulla oblongata and midbrain • helps regulate rate and depth of breathing • relays nerve impulses to and from 1. medulla oblongata and brainstem via longitudinal tracts 2. cerebellum via transverse tracts Origins of CN V, VI, VII, VIII 28 Medulla Oblongata • enlarged continuation of spinal cord running through foramen magnum of skull • conducts all ascending (olive) and descending (pyramids - decussation) impulses between brain and spinal cord • contains cardiac, vasomotor, and respiratory control centers • nucleus gracilis and nucleus cunneatus on dorsal side; sensory info, cross over, then send to thalamus Origins (nuclei) of: CN IX, X, XI, and XII 29 Reticular Formation • complex network of nerve fibers scattered throughout the brain stem • extends into the diencephalon • connects to centers of hypothalamus, basal nuclei, cerebellum, and cerebrum • filters incoming sensory information; habituation • modulates pain • arouses cerebral cortex into state of wakefulness Ascending portion is called the ‘reticular activating system’ (prefix = reticulo-) 30 Cerebellum • integrates sensory information concerning position of body parts • coordinates skeletal muscle activity • helps to maintain posture •May also be involved in several sensory, linguistic, emotional and non-motor functions • virtually all fibers entering and leaving are ispsilateral Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 31 Functions of Parts of Brain Part of Brain Motor areas Primary motor cortex (Precentral gyrus) Broca’s area (motor speech area) Major Function Voluntary control of skeletal muscles Controls muscles needed for speech Frontal eye field Sensory areas Cutaneous Sensory Area (postcentral gyrus) Controls muscles needed for eye movement Visual area (occipital lobe) Auditory area (temporal lobe) Association areas (all lobes) Receives visual sensations Receives auditory sensations Analyze and interpret sensory experiences; coordinate motor responses memory, reasoning, verbalization, judgment, emotions Subconscious control certain muscular activities, e.g., learned movement patterns (a nucleus is a collection of neuron cell bodies in the CNS); putamen, globus pallidus, caudate controls emotions , produces feelings, interprets sensory impulses, facilitates memory storage and retrieval (learning!) Basal nuclei Limbic system Diencephalon Thalamus Hypothalamus Brainstem Midbrain Pons Medulla Oblongata Reticular formation (system) Cerebellum Receives somatic sensations gateway for sensory impulses heading to cerebral cortex, receives all sensory impulses (except smell) Vital functions associated with homeostasis Major connecting center between spinal cord and brain and parts of brainstem; contains corpora quadrigemina (visual and auditory reflexes) Helps regulate rate and depth of breathing, relays nerve impulses to and from medulla oblongata and cerebellum Contains cardiac, vasomotor, and respiratory control centers, contains various nonvital reflex control centers (coughing, sneezing, vomiting) Filters incoming sensory information; habituation , modulates pain, arouses cerebral cortex into state of wakefulness (reticular activating system) Subconscious coordination of skeletal muscle activity, maintains posture 32 Spinal Cord Structure • extends from the foramen magnum to 2nd lumbar vertebra • cervical and lumbar enlargements • cauda equina (horse’s tail) – thin nerve fibers that exit at different level than they arise (note that spinal cord does not extend into this area of the lumbar spine). Begins around L2 and extends to S5. Good area for lumbar puncture and collection of CSF. Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 35 Meninges of the Spinal Cord Figures from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 Space between the dura mater and the vertebral body is called the epidural space 36 Cross Section of Spinal Cord The spinal cord… • is a center for spinal reflexes • aids in locomotion • is a conduit for nerve impulses to and from the brain 37 Organization of Spinal Gray Matter You should know the major areas of gray matter of within the spinal cord: Posterior = sensory Lateral = visceral motor Anterior = somatic motor Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 38 Organization of Spinal White Matter Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 39 Tracts of the Spinal Cord • Ascending tracts conduct sensory impulses to the brain • Descending tracts conduct motor impulses from the brain to motor neurons reaching muscles and glands All the axons in a tract share a common origin and destination Tracts are usually named for their place of origin (1st) and termination (2nd) Most axons cross over during their travel. What will this mean clinically? 40 Ascending Tracts • fasciculus cuneatus/gracilis - fine touch, pressure, body movement - cross (decussate) in medulla 3 • spinothalamic - crude pain, temperature, pressure, and touch - cross in spinal cord • spinocerebellar - subconscious coordination of muscle movements (1st and 2nd order neurons) - ipsilateral Decussation (crossing over) 2 1 41 1st, 2nd, and 3rd Order Sensory Neurons 1st order neuron – from receptor to the spinal cord (cell bodies are located in the dorsal root ganglion) 3 2nd order neuron – from spinal cord to thalamus 3rd order neuron – from thalamus to sensory cerebral cortex - terminate in the cerebral cortex Decussation 2 1 42 Descending Tracts • corticospinal (direct, pyramidal) - voluntary movement of skeletal muscles - lateral cross in medulla - contralateral Upper motor – begin in precentral gyrus of cortex • reticulospinal (indirect, extrapyramidal) - subconscious muscle tone, sweat glands - some lateral cross, anterior do not cross • rubrospinal (indirect, extrapyramidal) - subconscious regulation of upper limb tone/movement - cross in brain (less important in humans) Decussation Lower Upper MN – Cerebral cortex to spinal cord Lower MN – Spinal cord to effector 43 Review • The brain is protected by the – – – – Skull bones Meninges CSF Blood-brain barrier • The meninges of the brain and spinal cord consist of the – Dura mater – Arachnoid (membrane) – Pia mater 44 Review • Important motor areas of cerebral cortex – Precentral gyrus (Primary motor area) – Broca’s area – Frontal eye field • Important sensory areas of cerebral cortex – Postcentral gyrus (Primary cutaneous sensory) – Visual area (occipital lobe) – Auditory area (temporal lobe) • The spinal cord is a – Center for spinal reflexes – Conduit for nerve impulses to and from the brain 45 Review 46 Review Spinal cord contains nerve tracts Ascending = sensory Descending = motor 47