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chapter 13 - Dr. Rick · PDF fileChapter 13 – Spinal Cord and ... Gray’s anatomy! Conus medullaris! ... 41! Peripheral Nerves and Nerve Plexuses

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Text of chapter 13 - Dr. Rick · PDF fileChapter 13 – Spinal Cord and ... Gray’s anatomy!...

  • Chapter 13 Spinal Cord and Spinal Nerves!

    1!

    Chapter 13!The Spinal Cord and Spinal Nerves!

    2!

    SECTION 13-1 !The brain and spinal cord make up the central nervous system, and the cranial nerves and spinal nerves constitute the peripheral nervous system!

    3!

    Grouping of Neural Tissues (1 of 3)!White matter! Myelinated (and unmyelinated) neuron processes! Schwann cells in PNS! Oligodendrocytes in CNS!

    Gray matter! Nerve cell bodies and dendrites! Unmyelinated axons! Neuroglia (e.g. astrocytes)!

    Nerve! Bundle of nerve fibers (axons) outside the CNS! Has associated CT layers!

  • Chapter 13 Spinal Cord and Spinal Nerves!

    2!

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    Grouping of Neural Tissue (2 of 3)!

    Ganglion! Collection of nerve cell bodies outside of the

    CNS! E.g. Dorsal root ganglion!

    Nucleus! Collection of nerve cell bodies with a

    common function found inside the CNS! In brain or spinal cord! Unmyelinated! E.g. Basal nuclei!

    5!

    Grouping of Neural Tissue (3 of 3)!

    Columns are major regions of cord! E.g., posterior columns!

    Tracts are bundles of axons with common:! Structural characteristics (e.g. axon diameter,

    myelinated or not)! Function/direction! E.g., spinothalamic tract!

    Ascending tracts (in cord) = sensory!Descending tracts (in cord) = motor!Horns! Major areas of gray matter in spinal cord!

    6!

    SECTION 13-2 !The spinal cord is surrounded by three meninges and conveys sensory and motor information!

  • Chapter 13 Spinal Cord and Spinal Nerves!

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    Gross Anatomy of the Spinal Cord Figure 13-2!

    8!

    Spinal Cord Functions/Anatomy!

    Spinal cord functions:! Convey sensory information to brain! Convey motor information to PNS! Reflexively integrate sensory and motor info!

    Gross anatomical features:!Length! Extends from medulla to L1L2 in adults! 16 to 18 in. long! About 0.5 in. diameter!

    9!

    Spinal Cord Gross Anatomy (1 of 2)!

    Enlargements:!Regions where cord is

    thicker! Cervical enlargement!

    Fibers to and from arms! Lumbar enlargement!

    Fibers to and from legs!Conus medullaris! Tapered end of the

    cord! About L1 or L2!

    E

    E E

  • Chapter 13 Spinal Cord and Spinal Nerves!

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    Spinal Cord Gross Anatomy (2 of 2)!

    Filum terminale! Fibrous extension of pia mater! Forms part of coccygeal ligament!

    Coccygeal ligament! Dura mater + filum terminale (pia)! Attaches conus medullaris to coccyx!

    Cauda equina (horses tail)! Nerves arising from lower portion of cord! Descend in spinal canal! Exit spinal canal as spinal nerves!

    11!

    Conus Medullaris, Filum Terminale!

    Grays anatomy!www.bartleby.com/107/illust661.html!

    Conus medullaris!

    Filum terminale -!Intradural portion!

    Filum terminal - !extradural portion!(coccygeal ligament)!1st coccygeal!

    vertebra!

    Dura mater!

    Subarachnoid!space!

    2nd sacral vertebra!

    1st lumbar!Vertebra!

    12!

    Spinal Tap, Spinal Nerves!Spinal tap! Deliver anesthetics, sample CSF fluid or

    pressure, etc.! Done between L3 and L4 or L4 and L5!

    (Cord not present here)!Spinal nerves contain two roots! Spinal nerves are mixed nerves! Ventral root - motor ! Dorsal root - sensory ! Dorsal root ganglion!

    Sensory cell bodies (unipolar neurons)!

  • Chapter 13 Spinal Cord and Spinal Nerves!

    5!

    13!

    Gross Anatomy of the Spinal Cord Figure 13-2b!

    motor!

    sensory!

    mixed!

    14!

    The Spinal Meninges Figure 13-3a!

    15!

    Spinal Meninges and Associated Structures!

    Continuous with cranial meninges at F. magnum!Functions:! Provide support, stability, shock absorption!

    !!Epidural space:! Between dura mater and walls of vertebral

    canal! Contains areolar CT, blood vessels! Cushions cord!

  • Chapter 13 Spinal Cord and Spinal Nerves!

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    Dura Mater!

    Dura mater = tough mother! Not firmly attached to bone (as in cranium)! Dense irregular CT! Inner lining of simple squamous EPI! Tubular portion runs from F. Magnum to S2!

    Fuses to form coccygeal ligament (with filum terminale) that extends to coccyx!Fuses with CT coverings of spinal nerves!

    Subdural space! Probably not present in life!

    17!

    Arachnoid Membrane!

    Arachnoid = spider-like = refers to trabeculae! Avascular! Simple squamous EPI + CT trabeculae!

    Collagen + elastin fibers form trabeculae! EPI adheres to dura across subdural space! Extends with dura to end of intradural portion

    of filum terminale, so roots of nerves making up the cauda equina are in subarachnoid space!

    Subarachnoid space! Contains cerebrospinal fluid (CSF)!

    18!

    Pia Mater!

    Pia mater = soft or delicate mother! Adheres to surface of brain and cord! Delicate collagen and elastin fibers! Highly vascular! Runs to coccyx as filum terminale (with dura,

    forms coccygeal ligament)!Denticulate (dentate) ligaments (Fig. 13-5)! Formed from pia mater! Extend through arachnoid to attach to dura! Suspend cord within subarachnoid space!

  • Chapter 13 Spinal Cord and Spinal Nerves!

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    The Spinal Cord and Spinal Meninges!

    Figure 13-3b!

    Note orientation compared to that in Figure 13-5!

    20!

    SECTION 13-3 !Gray matter is the region of integration and command, and white matter carries information from place to place!

    21!

    Sectional Organization of Cord Figure 13-5b!

    Note orientation compared to that in Figure 13-3!

  • Chapter 13 Spinal Cord and Spinal Nerves!

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    Internal Anatomy of the Cord!

    Ventral (anterior) median fissure !(A fissure is larger than a sulcus.)!

    Dorsal (posterior) median sulcus !(smaller than fissure)!

    Gray commissures!Commissure = crossing from one side of the

    body to the other!Gray = gray matter!

    Central canal!Contains CSF!

    23!

    Gray Matter in the Cord see Figure 13-5a!

    Nuclei - collections of cell bodies with a similar function!

    Ventral (anterior) gray horns! Somatic motor nuclei! Efferent information to skeletal muscles!

    Lateral gray horns! Visceral (autonomic) motor nuclei! Only in thoracic and lumbar segments!

    Dorsal (posterior) gray horns (see slide #63)! Sensory area! Somatic and autonomic (visceral) nuclei!

    24!

    Sectional Organization of Cord Figure 13-5a!

    Note interneurons in dorsal horns!

  • Chapter 13 Spinal Cord and Spinal Nerves!

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    White Matter Columns and Tracts!

    Columns:! Large collections of fibers conveying

    information to or from the brain! Have similar origin and similar destinations!

    Tracts:! Collections of fibers within a column! Carry same type of information in the same

    direction to the same destination!

    26!

    Examples of Columns and Tracts!

    Posterior columns! Sensory (ascending)!

    Spinothalamic tracts! Sensory (ascending)!

    Corticospinal tracts! Motor (descending)! Voluntary movements!

    Vestibulospinal tracts! Motor (descending)! Automatic (involuntary) movements!

    Note that the name usually tells you the direction of information

    flow.!

    27!

    Sensory Columns and Tracts Figure 15-4!

    Note organization and direction. Do not try to memorize locations.!

    Posterior column pathway

    Spinothalamic pathway

  • Chapter 13 Spinal Cord and Spinal Nerves!

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    Motor Columns and Tracts Figure 15-8!

    Lateral corticospinal tract

    Vestobulospinal tract

    Anterior corticospinal tract

    Note organization and direction. Do not try to memorize locations.!

    29!

    SECTION 13-4 !Spinal nerves form plexuses that are named according to their level of emergence from the vertebral canal!

    30!

    Spinal Nerves!

    Spinal nerves are mixed nerves! Contain both sensory and motor fibers!

    Exist in 31 pairs!Exit vertebral canal via intervertebral foramina! Named for where they exit vertebral column!

    Cord stops at level of L2! Nerves exiting below this level form the cauda

    equina!

  • Chapter 13 Spinal Cord and Spinal Nerves!

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    31!

    Spinal Nerve Categories Figure 13-9!Pairs of spinal nerves:!! 8 cervical !

    (C1 exits between atlas and occipital bone)!

    12 thoracic! 5 lumbar! 5 sacral! 1 coccygeal!31 pairs!

    32!

    Peripheral Nerve Anatomy Figure 13-6!

    Connective tissue coverings!1. Epineurium! Surrounds entire nerve!

    2. Perineurium! Delineates fascicles

    (bundles)!3. Endoneurium! Surrounds individual

    nerve fibers!

    Does this terminology seem familiar?!

    33!

    Rami (Branches) of Spinal Nerves!

    Ramus = branch; plural = rami!1. Dorsal ramus! Information to and from skin, skeletal muscles

    of back! Somatic and visceral, both motor and sensory!

    !2. Ventral ramus! Information to and from ventrolateral body

    surface, body wall and limbs! Somatic and visceral, both motor and sensory! Form plexuses or thoracic (intercostal) nerves!

  • Chapter 13 Spinal Cord and Spinal Nerves!

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    34!

    Nerve Roots and Rami modified from Fig. 13-3b!

    Dorsal!

    Ventral!

    Dorsal root!Dorsal root

    ganglion!

    Ventral root! Denticulate ligament!

    Sympathetic chain ganglion!

    Ventral ramus!

    Dorsal ramus!

    Rami communicantes!

    35!

    Rami Communicantes (much more in Ch. 16)!3. Rami communicantes! Communicate between ventral rami and

    sympathetic ganglia! Visceral sensory and visceral motor! Information to and from interocepto

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