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    Introduction To Neuroanatomy

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    Pratik Dhakal
    The nervous system is made up of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves). The brain is divided into three main parts - the cerebrum, cerebellum, and brainstem. Each part of the brain controls different functions. The nervous system uses neurons and glial cells to transmit signals and regulate bodily functions both voluntarily and involuntarily through the somatic and autonomic nervous systems.

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    Introduction To Neuroanatomy

    Uploaded by

    Pratik Dhakal
    307 views49 pages
    The nervous system is made up of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves). The brain is divided into three main parts - the cerebrum, cerebellum, and brainstem. Each part of the brain controls different functions. The nervous system uses neurons and glial cells to transmit signals and regulate bodily functions both voluntarily and involuntarily through the somatic and autonomic nervous systems.

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    Introduction to Neuroanatomy

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    The nervous system is made up of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves). The brain is divided into three main parts - the cerebrum, cerebellum, and brainstem. Each part of the brain controls different functions. The nervous system uses neurons and glial cells to transmit signals and regulate bodily functions both voluntarily and involuntarily through the somatic and autonomic nervous systems.

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    Download as ppt, pdf, or txt
    307 views49 pages

    Introduction To Neuroanatomy

    Uploaded by

    Pratik Dhakal
    The nervous system is made up of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves). The brain is divided into three main parts - the cerebrum, cerebellum, and brainstem. Each part of the brain controls different functions. The nervous system uses neurons and glial cells to transmit signals and regulate bodily functions both voluntarily and involuntarily through the somatic and autonomic nervous systems.

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    of 49

    Fernando J.

    Peraldo, MD,
    MPH

    The Nervous System


    the major controlling, regulatory, and

    communicating system in the body.


    the center of all mental activity including
    thought, learning, and memory.
    Together with the endocrine system controls
    the functions of the body; responsible for
    regulating and maintaining homeostasis.
    is made up of the brain, the spinal cord, and the
    (peripheral) nerves that transmit information into and
    out of the brain and spinal cord.

    The Nervous System


    Central Nervous System (CNS)

    brain
    spinal cord
    Peripheral Nervous System
    nerve fibers
    nerve ganglia

    THE HUMAN BRAIN


    divided into

    two halves, or
    hemispheres,
    which are
    separated by
    a very deep
    crevice.

    THE HUMAN BRAIN


    The brain is made up of three major parts:

    the cerebrum, the brainstem, and the


    cerebellum.
    There is a large bundle of "nerves" that
    relays messages between the left and right
    hemispheres.
    brain = cerebrum + cerebellum + brainstem

    View of the right side of the brain from the midline

    THE HUMAN BRAIN


    The brainstem a "stalk" connecting the

    brain and the spinal cord


    - responsible for many life-sustaining
    functions, including regulation of breathing,
    heart rate, and blood pressure
    - have parts concerned with regulation of
    sleep-wakefulness cycles and with levels of
    alertness

    THE HUMAN BRAIN


    The cerebellum

    - concerned with regulating movements


    - also plays an important role in
    procedural memory and classical
    conditioning

    THE HUMAN BRAIN


    The cerebrum

    - concerned with our ability to think, to


    plan, to process sensory information, and
    to move; responsible for those abilities
    that make us most uniquely human

    4 geographic regions, or lobes of


    cerebrum

    Summary of localization of function in the brain


    Function

    Description

    Location

    Motor

    Control of voluntary movement

    The back edge of the frontal lobes

    Somatosensory

    Bodily sensations, including heat,


    cold, pain, pressure, and body
    position

    The front edge of the parietal lobes

    Vision

    Ability to see

    Occipital lobe

    Auditory

    Ability to hear

    Top part of the temporal lobe

    Speech Production
    (Motor Speech)

    Ability to produce speech sounds

    "Broca's" area in the frontal lobe in


    the left hemisphere

    Speech planning and


    comprehension
    ("sensory" speech)

    Ability to plan and understand


    speech

    "Wernicke's" area at the junction of


    the partiety, temporal, and occipital
    lobes in the left hemisphere

    Biologically based
    motives

    Control of drives to satisfy basic


    biological needs, such as hunger
    and thirst

    Hypothalamus, loacted at the bottom


    of the brainstem, near where the
    brainstem meets the cerebrum

    Limbic functions

    Regulation of emotions

    "Limbic system" consisting of a group


    of brain areas located near the corpus
    callosum and extending into the
    temporal lobes

    localization of functions in the left hemisphere of the cerebrum

    The Spinal Cord


    connected to the brain, descends down the

    middle of the back and is surrounded and


    protected by the bony vertebral column
    surrounded by a clear fluid called Cerebral
    Spinal Fluid (CSF), that acts as a cushion to
    protect the delicate nerve tissues against
    damage from banging against the inside of
    the vertebrae
    consists of millions of nerve fibers which
    transmit electrical information to and from
    the limbs, trunk and organs of the body,
    back to and from the brain

    1 Spinal Nerve
    2 Dorsal Root Ganglion
    3 Dorsal Root (Sensory)
    4 Ventral Root (Motor)
    5 Central Canal
    6 Grey Matter
    7 White Matter

    The Spinal Cord:Ascending and


    Descending Spinal Tracts
    Ascending tracts

    - within the spinal cord carry sensory


    information from the body, upwards to
    the
    brain, such as touch, skin
    temperature, pain
    and joint
    position.
    Descending tracts
    - within the spinal cord carry information
    from
    the brain downwards to initiate
    movement and
    control body
    functions.

    Spinal Nerves
    branch off the spinal cord and pass

    out through a hole in each of the


    vertebrae
    carry information from the spinal
    cord to the rest of the body, and
    from the body back up to the brain.

    Spinal Nerves
    4 main groups of spinal nerves

    - Cervical Nerves "C" : (nerves in the


    neck) supply movement and feeling to
    the arms,
    neck and upper trunk. Also
    control breathing.
    - Thoracic Nerves "T" : (nerves in the
    upper back) supply the trunk and
    abdomen.
    - Lumbar Nerves "L" and Sacral Nerves
    "S" : (nerves in the lower back) supply the
    legs, the bladder, bowel and sexual organs.

    Spinal Cord Nerve Levels

    The level of the spinal


    cord segments do not
    relate exactly to the
    level of the vertebral
    bodies i.e. damage to
    the bone at a
    particular level e.g. L5
    vertebrae does not
    necessarily mean
    damage to the spinal
    cord at the same
    spinal nerve level.

    Peripheral Nervous
    system

    located outside the CNS


    contains nerves that extend throughout the

    body
    Two parts to the PNS
    1. Somatic nervous system - neurons deal with
    voluntary actions, Ex. run, play, swing, hit
    2. Autonomic nervous system - generally deal
    with involuntary acts

    The Autonomic Nervous System


    a part of the nervous system that is

    concerned with regulating internal bodily


    functions that are generally considered to be
    involuntary or automatic, such as digestion,
    heart rate, blood pressure, glandular
    secretions, and tear production.
    made up of two parts with opposite
    functions:
    1. sympathetic nervous system
    2. parasympathetic nervous system.

    The Autonomic Nervous System


    sympathetic nervous

    system
    - the "fight or flight"
    system. It prepares the
    body for action
    - active when we are
    anxious or otherwise
    emotionally aroused
    - activity increases heart
    rate and blood pressure.

    parasympathetic nervous

    system
    - referred to as the
    "vegetative" system
    - nurtures and rebuilds the
    body
    - active during relaxation and
    rest
    - Activity decreases heart rate
    and blood pressure and
    promotes digestion

    ORGANIZATION OF THE
    NERVOUS SYSTEM

    Neurons
    - are the basic structural
    and functional units of the
    nervous system
    - conducting nerve
    impulses
    - highly specialized and
    amitotic

    - generally large nerve


    cells

    Neurons
    - generated before
    birth
    - responsible for
    the reception,
    transmission, and
    processing of
    stimuli; triggering
    of certain cell
    activities; and
    release of
    neurotransmitters

    Neurons

    3 parts of a
    neuron:
    - dendrites
    - cell body/
    perikaryon
    - axon

    Neurons
    Cell Body

    - the metabolic
    center of a neuron
    and contains the
    nucleus with at
    least one nucleolus
    and contains many
    of the typical
    cytoplasmic
    organelles but
    lacks centrioles

    Neurons
    Dendrites

    - are cytoplasmic
    extensions, or
    processes, that project
    from the cell body
    - usually, but not
    always, short and
    branching, which
    increases their surface
    area to receive signals
    from other neurons are called afferent
    processes because they
    transmit impulses to
    the neuron cell body.

    Neurons
    Axons

    - also cytoplasmic
    extensions, or
    processes,
    - there is only one axon
    that projects from each
    cell body
    - usually elongated,
    carries impulses away
    from the cell body
    (efferent process)
    - the "transmitting"
    process of the neurone

    Axons

    - may have infrequent


    branches called axon
    collaterals
    - Axons and axon
    collaterals terminate in
    many short branches or
    telodendria
    distal ends of the
    telodendria are slightly
    enlarged to form
    synaptic bulbs
    surrounded by a
    segmented, white, fatty
    substance called myelin
    or the myelin sheath.

    SYNAPSES
    morphologically

    specialised contacts
    between a bouton
    formed by one neuron,
    the presynaptic
    neuron,
    and the cell surface of
    another neuron,
    the postsynaptic
    neuron

    SYNAPSES
    Convert electrical signal from presynaptic

    cell into a chemical signal in the post


    synaptic cell
    Transmit information by releasing chemical
    messengers
    (neurotransmitters/neuromodulators)
    Formed by an axon terminal that delivers
    the signal and a region on the surface of
    another cell where a new signal is
    generated and a thin intercellular space
    called synaptic cleft

    Types of Neurons
    According to size and shape of their processes

    Multipolar more than 2 cell processes


    one axon, multiple
    dendrites
    Bipolar one dendrite and one axon
    Pseudounipolar single process close to the
    perikaryon and divides into
    2 branches, one extending
    to
    the peripheral ending, the
    other toward the CNS

    According to their functional role

    Motor (efferent) neurons control


    effector organs such as muscle
    fibers, exocrine, and endocrine
    glands
    Sensory (afferent) neurons reception of
    sensory stimuli from the
    environment and
    from within the body
    Interneurons - or association neurons, are
    located entirely within the CNS in which
    they form the connecting link
    between the
    afferent and efferent
    neurons.

    SUPPORT CELLS OF THE NERVOUS TISSUE

    Schwann cells

    - Support cells in
    peripheral nerves

    - form the myelin


    around myelinated
    peripheral axons.
    - also envelop
    unmyelinated axons,
    but without the
    dense membrane
    wrapping which
    characterizes
    myelin.

    SUPPORT CELLS OF THE NERVOUS TISSUE

    satellite cells
    - support cells in
    peripheral ganglia
    - cells immediately
    surrounding the
    ganglion cells as
    one flattened layer

    SUPPORT CELLS OF THE NERVOUS TISSUE

    Glial cells

    - most numerous cells


    within the central
    nervous system
    -10 times more
    abundant in
    mammalian brain than
    neurons
    - surround both cell
    bodies and their axonal
    and dendrite processes
    - non-neuronal,
    supporting cells,
    neuroglia.

    SUPPORT CELLS OF THE NERVOUS TISSUE


    Glial cells
    Astrocytes (or astroglia)

    - may be involved in
    the removal of
    transmitters from
    synapses and the
    metabolism of
    transmitters.
    the scar-forming cells of
    the CNS.
    - participate in the
    maintenance of the
    composition of the
    extracellular fluid.

    SUPPORT CELLS OF THE NERVOUS TISSUE


    Glial cells

    Microglia
    - small elongated cell with
    short irregular processes
    - phagocytic cells that
    represent
    the mononuclear phagocytic
    system in nerve tissue
    - involved in inflammation
    and
    repair in the adult CNS and
    release neutral proteases
    and
    oxidative radicals
    - mesodermal origin, derived
    from the cell line which also
    gives rise to monocytes, i.e.
    macrophage precursors
    which circulate in the blood
    stream

    SUPPORT CELLS OF THE NERVOUS TISSUE


    Oligodendroglia
    - form myelin sheath around axons in the CNS
    - the functional homologue of peripheral
    Schwann
    cells.
    - have fewer and shorter processes.
    - in contrast to Schwann cells in the periphery,
    form parts of the myelin sheath around several
    axons.
    -responsible for normal propagation of
    action potentials

    SUPPORT CELLS OF THE NERVOUS TISSUE


    ependymal cells
    -

    low columnar epithelial cells lining the ventricles of the


    brain and central canal of the spinal cord
    - often cilated, lack tight junctions which allows a free
    exchange between cerebrospinal fluid and nervous tissue
    - have long basal processes and form the ventricular lining
    over the few CNS regions in which the blood-brain barrier
    is incomplete.
    - form tight junctions and control the exchange of
    substances between these regions and surrounding
    nervous tissue or cerebrospinal fluid.

    Review: Introduction to the Nervous


    System
    The nervous system is the major controlling,

    regulatory, and communicating system in


    the body. It is the center of all mental
    activity including thought, learning, and
    memory.
    The various activities of the nervous system
    can be grouped together as three general,
    overlapping functions: sensory, integrative,
    and motor.
    Neurons are the nerve cells that transmit
    impulses. Supporting cells are neuroglia.

    Review: Introduction to the Nervous


    System
    The three components of a neuron are a

    cell body or soma, one or more afferent


    processes called dendrites, and a single
    efferent process called an axon.
    The central nervous system consists of the
    brain and spinal cord. Cranial nerves, spinal
    nerves, and ganglia make up the peripheral
    nervous system.
    The afferent division of the peripheral
    nervous system carries impulses to the
    CNS; the efferent division carries impulses
    away from the CNS.

    Review: Introduction to the Nervous


    System
    There are three layers of meninges around

    the brain and spinal cord. The outer layer is


    dura mater, the middle layer is arachnoid,
    and the innermost layer is pia mater.
    The spinal cord functions as a conduction
    pathway and as a reflex center. Sensory
    impulses travel to the brain on ascending
    tracts in the cord. Motor impulses travel on
    descending tracts.

    End of lecture
    Thank you

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