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    SPINE

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    Madhavarao Maddisetty
    The document discusses the anatomy and organization of the spinal cord and peripheral nervous system, including that the spinal cord is covered by meninges and has dorsal and ventral roots that carry nerves exiting at each vertebrae level, and describes the pathways of ascending and descending tracts that carry sensory and motor information between the spinal cord and brain.

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    SPINE

    Uploaded by

    Madhavarao Maddisetty
    8 views27 pages
    The document discusses the anatomy and organization of the spinal cord and peripheral nervous system, including that the spinal cord is covered by meninges and has dorsal and ventral roots that carry nerves exiting at each vertebrae level, and describes the pathways of ascending and descending tracts that carry sensory and motor information between the spinal cord and brain.

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    The document discusses the anatomy and organization of the spinal cord and peripheral nervous system, including that the spinal cord is covered by meninges and has dorsal and ventral roots that carry nerves exiting at each vertebrae level, and describes the pathways of ascending and descending tracts that carry sensory and motor information between the spinal cord and brain.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    8 views27 pages

    SPINE

    Uploaded by

    Madhavarao Maddisetty
    The document discusses the anatomy and organization of the spinal cord and peripheral nervous system, including that the spinal cord is covered by meninges and has dorsal and ventral roots that carry nerves exiting at each vertebrae level, and describes the pathways of ascending and descending tracts that carry sensory and motor information between the spinal cord and brain.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 27

    • Spinal Cord Anatomy

    • Meninges cover the spinal cord


    • Nerves leave at the level of each
    vertebrae
    • Dorsal root
    • Associated with the dorsal root ganglia –
    collections of cell bodies outside the central
    nervous system

    •Ventral root
    • Peripheral Nervous System

    • Nerves and ganglia outside the central


    nervous system

    • Nerve = bundle of neuron fibers

    • Neuron fibers are bundled by


    connective tissue
    • Structure of a Nerve

    • Endoneurium
    surrounds each fiber

    • Groups of fibers are


    bound into fascicles
    by perineurium

    • Fascicles are bound


    together by
    epineurium
    grey matter in the centre (the butterfly shape)
    white matter surrounds it
    opposite arrangement is found in the cortex of the brain..
    •The diameter of the
    spinal cord is the
    largest in the cervical
    region and there is a
    larger proportion of
    white matter
    compared to gray
    matter.
    •The diameter of the sacral
    region of the spinal cord
    (which is surrounded by the
    T12/L1 vertebrae) is the
    smallest and the proportion of
    gray matter is largest in the
    spinal cord.
    Cross Section of Spinal Cord
    Cross Section of Spinal Cord

    • White matter: • Gray matter:


    • Myelinated axons • Neuron cell cell bodies,
    dendrites, axons
    forming nerve tracts
    • ‘Horns’:
    • Fissure and sulcus • Posterior (dorsal)
    • Three columns: • Anterior (ventral)
    • Ventral • Lateral

    • Dorsal
    • Lateral • Commissures:
    • Gray: Central canal
    • White
    Functional Organization of the Nuclei
    within the Gray Matter
    of the Spinal Cord
    Location of Ascending and
    Descending Tracts of the Spinal Cord
    •See ANS
    •lecture
    •The cervical
    enlargement contains the
    neurons that innervate the
    upper limbs

    •The lumbar
    enlargement contains
    the neurons that
    innervate the lower
    limbs.
    •The tapering end
    of the spinal cord is
    called the conus
    medullaris.

    •The conus
    medullaris is
    surrounded by L1
    in and adult and
    L2 in a child.
    •The adult spinal cord
    terminates at the level of
    the first lumbar vertebra
    (L1)

    •In a developing child,


    the spinal cord can
    extend to the level of
    the second lumbar
    vertebra (L2)
    •The cauda
    equina
    (horse’s tail)
    is composed
    of nerves that
    arise from
    the conus
    medullaris
    and extend
    inferiorly.
    •The filum terminale,
    which is composed of
    pia mater, extends from
    the conus medullaris to
    the coccyx. Note the
    subarachnoid space also
    continues for some
    distance.
    •There are 31
    pairs of spinal
    nerves that
    serve defined
    segments of the
    human body.
    •‘Plexus’:
    •intermingling /
    merging of nerves
    and subsequent re-
    organisation
    •--> distribution of
    peripheral nerves
    is different from
    that of spinal
    nerves
    •The Organisation of the Nervous System

    •spinal cord brain


    •CNS
    •spinal nerves (31p) cranial nerves (12p)

    •PNS
    •sensory motor •motor sensory

    • Sensory information has to be passed on from the spinal cord to the brain
    • ascending pathways (red)

    • Commands from the brain have to be sent out to the PNS


    • descending pathways (green)
    •Ascending (afferent) spinal tracts:

    • Pathways that carry sensory information to a conscious level

    •receptor
    •(e.g. pain receptor in skin)

    • primary sensory neurone


    •(cell body in dorsal root ganglia)

    • second order neurone


    •(in the spinal cord or brainstem)
    • target area: cortex
    • third order neurone •somatosensory (somatic sensory)
    •(in thalamus)
    area
    •(postcentral gyrus) of the cortex
    •Example

    •Conscious
    •perception

    •Light touch
    •Sensory information travels to the brain via 3 main pathways:

    To somatosensory cortex
    1) Spinothalamic system (lateral and anterior tract):
    somatosensory information to brain:pain and temperature, light touch,
    pressure, tickle, itch

    2) Dorsal column / medial lemniscus:


    Two-point discrimination, proprioception, pressure, vibration

    To cerebellum:
    3) Spinocerebellar system (posterior and anterior):
    proprioception, for comparator function
    Basic Organization of a
    Reflex Pathway
    Terms Associated with
    Reflex Pathways

    • Spinal Reflexes // Cranial Reflexes


    • Somatic Reflexes // Visceral (Autonomic)
    Reflexes
    • Monosynaptic Reflex // Polysynaptic Reflex
    • Ipsilateral Reflex // Contralateral Reflex
    • Segmental Reflex // Intersegmental Reflex
    • Reciprocal innervation
    A Spinal, Somatic, Monosynaptic,
    Ipsilateral, Segmental Reflex
    demonstrating Reciprocal Innervation

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