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Vertebral Column Spinal Cord and Meninges

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									Vertebral Column, Spinal Cord and Meninges



ANNOUNCEMENTS

   1.   Faculty laboratory assignments for this week:

            o    Lab 1: Dr. Tank
            o    Lab 2: Dr. Sims, Dr. Benes
            o    Lab 3: Dr. Davies, Dr. Gilmore




   2.   Only the odd numbered tables will remove a section of the spinal cord today (see helpful hint #7
        below).

   3.   Please remember to cover the yellow pails and the covered trash cans when you leave at the end of
        the day.

   4.   Place only human material in covered containers. The yellow pails are at table side for your
        convenience. The covered trash cans with the red liners (biohazard bags) are also for human
        material. Paper and gloves should be placed in the gray trash cans by the sinks.



ASSIGNMENTS

        Moore's Clinically Oriented Anatomy: 459-489
        Grant's Dissector: 139-143; Start at "Vertebral Canal and Spinal Cord"; Continue to the
        end of the chapter. We will delete the suboccipital region (pages 136-139) from our
        study. You will not be tested on the deleted material.



HELPFUL HINTS

   1.   Limit your study of the erector spinae muscles - Dissection of the erector spinae muscles should
        stop when you see three columns of muscle. Learn only the names of the 3 columns of erector
        spinae (iliocostalis, longissimus and spinalis), the segmental nature of blood and nerve supply and
        the group action. Don't learn any subparts of the three columns or details about them.

   2.   We will not dissect the transversospinal group - A brief study of the function of these complex
        muscles will be sufficient.

   3.   The dissector (pgs. 140-141) gives no definitive instructions on the length of the vertebral canal to
        be exposed and suggests that you consult your instructor. We want you to dissect the entire length
        of the vertebral column from C4 to the coccyx.

   4.   Detach the splenius muscle from its midline origin on the spines of C7-T6 and turn it laterally out
        of the way. Leave it attached at its insertion.

   5.   Completely remove the erector spinae muscles. Cut them off and place them in the yellow pail at
        your table. These muscles must be cut from the laminae so that you can clearly see the laminae of
       the vertebrae prior to performing the next step of the dissection. Go up as high as you can on the
       back of the neck - about to level C4. Caudally, be very cautious and remain near the midline of the
       sacrum when removing the muscles. Do not dissect too far laterally - you will damage the
       gluteal muscles.

  6.   Use a chisel to perform a laminectomy. Examine an articulated skeleton near you and note the
       width of the lamninae and that these widths are not uniform throughout the length of the vertebral
       column. Observations of the laminae will help to guide you in making the laminectomy. Also, ask
       the faculty for help. Only one person can chisel at one time, so the others at the table should
       definitely keep their hands away from the dissection field while the chiseler is at work. Take turns.
       Protect your eyes against bits of flying debris.

  7.   Begin laminectomy at the mid-thoracic level and work both ways (superiorly & inferiorly). Go all
       the way to the coccyx inferiorly, but stop at C4 superiorly. Be careful when you get to sacral
       levels. Look at a figure of the vertebral column as seen in a lateral view (Netter plate 142) and
       notice that the sacrum is very superficial - do not chisel too deeply in the sacral region.

  8.   Students on odd numbered tables: Load a sharp blade and remove a section of the spinal cord
       and surrounding meninges to help you study the relationships of the meninges, specializations of
       pia, etc. Collect this specimen from the mid-thoracic level. Make this specimen of spinal
       cord/meninges about 6 inches long. Cut it in half in the transverse plane (keep the meninges and
       spinal cord together and cut the entire specimen) and give half to the next higher numbered (even
       numbered) table. Once the specimen is removed, this is a good time to look at the posterior
       longitudinal ligament.
       Students on even numbered tables: Keep the spinal cord intact in the vertebral canal of your
       cadaver and share it with your neighbors at the next lower numbered (odd numbered) table. It is
       OK to open the dura and examine the spinal cord in your cadaver, just don't cut the spinal cord.
       We will harvest these intact spinal cord specimens for you to use later this academic year in the
       Neuroscience course.



WHEN YOU FINISH THIS SECTION, YOU SHOULD BE ABLE TO PERFORM THE
FOLLOWING TASKS AND ANSWER THESE QUESTIONS

  1.   Draw and label a typical thoracic vertebra. Draw a lumbar vertebra and a cervical vertebra. How
       do they differ?

  2.   Describe the normal curvatures of the vertebral column. How do the adult curvatures differ from
       those of the newborn?

  3.   Name and describe three abnormal curvatures of the vertebral column.

  4.   What neural structure passes through a posterior sacral foramen? What neural structure passes
       through an anterior sacral foramen?

  5.   Could the sacral hiatus be used as a route for injecting an anesthetic into the epi- (extra-) dural
       space? Explain.

  6.   What is the nucleus pulposus? What role does it play in a "herniated disc"?

  7.   In the adult, at what vertebral level would you expect to find the 5th sacral spinal cord segment?
       The 12th thoracic spinal cord segment? The 1st cervical spinal cord segment?

  8.   What is the nerve supply for the deep group of back muscles?
   9.   Name the primary arterial supply for the deep group of back muscles.

   10. State the function of each member of the deep group of back muscles

   11. Describe the extent of each meninx. What anchors the spinal cord?

   12. Of what clinical significance is the vertebral venous plexus?

   13. What arteries supply the spinal cord?

   14. What is the cauda equina and how is it related to the lumbar subarachnoid space?

   15. At which vertebral level would it be safe to do a lumbar puncture? What is the supracristal line?

   16. Beginning with the skin, name in correct sequence, all structures penetrated when doing a lumbar
       puncture (a) in the midline and (b) slightly lateral to the midline by passing through the
       ligamentum flavum.



SURFACE ANATOMY OF THE BACK
     External occipital protuberance
     Vertebra prominens
     Iliac crest
     Scapula:

            o    Acromion
            o    Spine
            o    Medial (vertebral) border
            o    Inferior angle

        Erector spinae
        Vertebral furrow
        Posterior superior iliac spine
        Posterior axillary fold

CUTANEOUS NERVES OF THE BACK
     Branches of dorsal primary rami
     Branches of ventral primary rami

VERTEBRAL COLUMN
     Components

            o    Vertebrae
            o    Intervertebral discs


        Curvatures

            o    Normal
                         Cervical
                         Thoracic
                         Lumbar
                         Sacral
            o    Abnormal
                     Scoliosis
                     Lordosis
                     Kyphosis


        Parts of a typical vertebra

            o    Body
            o    Vertebral arch
                      Pedicles (paired)
                      Laminae (paired)
                      Transverse processes (paired)
                      Spinous process (single)
            o    Vertebral foramen


        Sacrum

            o    Sacral hiatus
            o    Posterior (dorsal) sacral foramina
            o    Anterior (ventral) sacral foramina


        Structures involving more than one vertebra:

            o    Vertebral canal
            o    Intervertebral foramina
            o    Ligaments
                       Anterior longitudinal
                       Posterior longitudinal
                       Interspinous
                       Supraspinous
                                Ligamentum nuchae
                       Ligamentum flavum

EXTRINSIC BACK MUSCLES (superficial back muscles)
Review these muscles which were dissected with the upper limb.
        Trapezius m.
        Latissimus dorsi m.
        Rhomboideus major m.
        Rhomboideus minor m.
        Levator scapulae m.
INTERMEDIATE BACK MUSCLES
        Serratus posterior superior m.
        Serratus posterior inferior m.
INTRINSIC BACK MUSCLES (deep back muscles)
        Splenius mm.

            o    Capitis
            o    Cervicis
           Erector spinae mm.

           o     Iliocostalis
           o     Longissimus
           o     Spinalis


       Transversospinal group

           o     Semispinalis mm.
                      Capitis
           o     Multifidus mm.
           o     Rotatores mm.

SPINAL MENINGES
      Dura mater

           o     Coccygeal ligament


       Arachnoid

       Pia mater

           o     Denticulate ligament (2)
           o     Filum terminale


MENINGEAL-ASSOCIATED SPACES
     Epidural (extradural) space

           o     Fat
           o     Venous plexuses


       Subdural space

       Subarachnoid space

           o     Cerebrospinal fluid (CSF)


SPINAL CORD
      Location

       External appearance

           o     Cervical enlargement
           o     Lumbar enlargement
           o     Nerve rootlets
           o     Conus medullaris - L1/L2
           o     Cauda equina
Organization

                o     Spinal segment




                                        Topographic Anatomy of the Back

 Structure/Space                       Boundaries/Description                                    Significance

triangle of              a triangle located medial to the inferior angle of the        triangle of auscultation is used
auscultation             scapula; it is bounded by the trapezius m. medially,          to listen to (auscultate) the
                         rhomboideus major m. superiorly and the latissimus            lungs because the stethoscope
                         dorsi m. inferiorly; its floor is the posterior thoracic      can be placed close to the
                         wall                                                          thoracic wall at this location

vertebral furrow         midline furrow down the back                                  surface landmark that indicates
                                                                                       the location of the vertebral
                                                                                       spines; the erector spinae
                                                                                       muscle masses lie on either side
                                                                                       of it

natal cleft              midline cleft between the buttocks                            natal cleft lies between the
                                                                                       gluteus maximus muscles

vertebra                 the C7 vertebra, so named because its spine is                vertebra prominens is an easily
prominens                easily seen and palpated                                      palpable landmark which
                                                                                       indicates the level of transition
                                                                                       from cervical to thoracic
                                                                                       vertebra

external occipital       a bump located in the midline on the posterior                the medial ends of the superior
protuberance             surface of the occipital bone                                 nuchal lines meet at the
                                                                                       external occipital protuberance;
                                                                                       the ligamentum nuchae attaches
                                                                                       here

lumbar triangle          a triangle defined by the border of the latissimus            lumbar triangle may be the site
                         dorsi m. medially, the external abdominal oblique             of an abdominal hernia; also
                         m. laterally and the iliac crest inferiorly; its floor is     known as: triangle of Petit
                         the internal abdominal oblique m.


                                           Cutaneous Nerves of the Back

 Nerve              Source      Branches               Motor                         Sensory                 Notes

ramus,         first branch     numerous      to the deep back           general sense (touch,         a mixed nerve
dorsal         off of the                     mm.; sympathetic           pressure, pain, heat,         containing both
primary        dorsal side                    innervation to the         cold, etc.) to the skin of    motor and
               of the spinal                  skin                       the back                      sensory fibers
               nerve

ramus,         first branch     numerous      to skeletal mm. of the general sense (touch,             a mixed nerve
ventral        off of the                     neck, trunk and        pressure, pain, heat,             containing both
primary      ventral side                 extremities;              cold, etc.) to the skin of   motor and
             of the spinal                sympathetic               the trunk (except the        sensory fibers
             nerve                        innervation to the        back) and extremities
                                          skin


                                 Posterior Thoracoappendicular Muscles

  Muscle           Origin         Insertion          Action       Innervation          Artery           Notes

trapezius       medial third    lateral third of   elevates      motor: spinal   transverse         named for
                of the          the clavicle,      and           accessory (XI), cervical a.        its shape;
                superior        medial side of     depresses     proprioception:                    trapezius is
                nuchal line,    the acromion       the scapula   C3-C4                              an example
                external        and the upper      (depending                                       of a muscle
                occipital       crest of the       on which                                         that
                protuberance,   scapular           part of the                                      migrates
                ligamentum      spine, tubercle    muscle                                           during
                nuchae,         of the scapular    contracts);                                      development
                spinous         spine              rotates the                                      from its
                processes of                       scapula                                          level of
                vertebrae C7-                      superiorly;                                      origin
                T12                                retracts                                         (cervical) to
                                                   scapula                                          its final
                                                                                                    position,
                                                                                                    pulling its
                                                                                                    nerve and
                                                                                                    artery along
                                                                                                    behind

latissimus      vertebral      floor of the        extends       thoracodorsal     thoracodorsal latissimus
dorsi           spines from    intertubercular     the arm       nerve (C7,8)      a.            dorsi tendon
                T7 to the      groove              and rotates   from the                        passes in
                sacrum,                            the arm       posterior cord                  close
                posterior                          medially      of the brachial                 relationship
                third of the                                     plexus                          to the teres
                iliac crest,                                                                     major
                lower 3 or 4                                                                     tendon at
                ribs,                                                                            their
                sometimes                                                                        insertions
                from the
                inferior angle
                of the
                scapula

levator         transverse      medial border      elevates    dorsal scapular     dorsal           levator
scapulae        processes of    of the scapula     the scapula nerve (C5); the     scapular a.      scapulae is
                C1-C4           from the                       upper part of                        named for
                vertebrae       superior angle                 the muscle                           its action
                                to the spine                   receives
                                                               branches of C3
                                                               & C4

rhomboideus spines of     medial border            retracts,     dorsal scapular   dorsal           named for
major       vertebrae T2- of the scapula           elevates      nerve (C5)        scapular a.      its shape
            T5            inferior to the          and rotates
                                spine of the       the scapula
                                scapula            inferiorly

rhomboideus inferior end        medial border      retracts,   dorsal scapular        dorsal            named for
minor       of the              of the scapula     elevates    nerve (C5)             scapular a        its shape
            ligamentum          at the root of     and rotates
            nuchae,             the spine of       the scapula
            spines of           the scapula        inferiorly
            vertebrae C7
            and T1


                                 Muscles of the Back - Intermediate Group

 Muscle          Origin          Insertion      Action        Innervation         Artery                Notes

serratus    ligamentum          ribs 1-4,      elevates    branches of         posterior        a respiratory
posterior   nuchae, spines      lateral to     the         the ventral         intercostal      muscle, it receives
superior    of vertebrae C7     the angles     upper       primary rami        aa. 1-4          ventral ramus
            and T1-T3                          ribs        of spinal                            innervation;
                                                           nerves T1-T4                         embryonically
                                                                                                related to the
                                                                                                intercostal muscles,
                                                                                                not the deep back
                                                                                                mm.

serratus    thoracolumbar       ribs 9-12,     pulls       branches of         lowest           a respiratory
posterior   fascia, spines of   lateral to     down        the ventral         posterior        muscle, it receives
inferior    vertebrae T11-      the angles     lower       primary rami        intercostal      ventral ramus
            T12 and L1-L2                      ribs        of spinal           a., subcostal    innervation;
                                                           nerves T9-T12       a., first two    embryonically
                                                                               lumbar aa.       related to the
                                                                                                intercostal muscles,
                                                                                                not the deep back
                                                                                                mm.


                                     Muscles of the Back - Deep Group

  Muscle          Origin        Insertion         Action         Innervation        Artery               Notes

splenius       ligamentum       mastoid        extends and      dorsal           supplied          named for its
capitis        nuchae and       process        laterally        primary          segmentally       shape: splenius
               spines of        and lateral    bends the        rami of          by: deep          means bandage
               C7-T6            end of the     neck and         spinal           cervical a.,      and capitis refers
               vertebrae        superior       head, rotates    nerves C2-       posterior         to the insertion of
                                nuchal line    head to the      C6               intercostal       this portion of the
                                               same side                         aa.               muscle

splenius       ligamentum       posterior      extends and      dorsal           supplied          named for its
cervicis       nuchae and       tubercles      laterally        primary          segmentally       shape: splenius
               spines of        of the         bends neck       rami of          by: deep          means bandage
               C7-T6            transverse     and head,        spinal           cervical a.,      and cervicis
               vertebrae        processes      rotates head     nerves C2-       posterior         refers to the
                                of C1-C3       to the same      C6               intercostal       insertion of this
                                vertebrae      side                              aa.               portion of the
                                                                                          muscle

iliocostalis    iliac crest    angles of     extends and      dorsal       supplied       the most lateral
                and sacrum     the ribs      laterally        primary      segmentally    part of the erector
                                             bends the        rami of      by: deep       spinae; it may be
                                             trunk and        spinal       cervical a.,   subdivided into
                                             neck             nerves C4-   posterior      lumborum,
                                                              S5           intercostal    thoracis and
                                                                           aa.,           cervicis portions
                                                                           subcostal
                                                                           aa., lumbar
                                                                           aa.

longissimus     transverse     transverse    extends and      dorsal       supplied       the intermediate
                process at     process at    laterally        primary      segmentally    part of the erector
                inferior       superior      bends the        rami of      by: deep       spinae;it may be
                vertebral      vertebral     trunk, neck      spinal       cervical a.,   subdivided into
                levels         levels and    and head         nerves C1-   posterior      thoracis, cervicis
                               mastoid                        S1           intercostal    and capitis
                               process                                     aa.,           portions
                                                                           subcostal
                                                                           aa., lumbar
                                                                           aa.

spinalis        spinous        spinous       extends and      dorsal       supplied       most medial part
                processes at   processes     laterally        primary      segmentally    of the erector
                inferior       at superior   bends trunk      rami of      by: deep       spinae; may be
                vertebral      vertebral     and neck         spinal       cervical a.,   subdivided into
                levels         levels and                     nerves C2-   posterior      thoracis, cervicis
                               base of the                    L3           intercostal    and capitis
                               skull                                       aa.,           portions
                                                                           subcostal
                                                                           aa., lumbar
                                                                           aa.

semispinalis    transverse   capitis:        extends the      dorsal       supplied       three parts are
                processes of back of         trunk and        primary      segmentally    named based on
                C7-T12       skull           laterally        rami of      by: deep       their insertions:
                             between         bends the        spinal       cervical a.,   capitis, cervicis
                             nuchal          trunk, rotates   nerves C1-   posterior      and thoracis;
                             lines;          the trunk to     T12          intercostal    semispinalis,
                             cervicis &      the opposite                  aa.,           multifidus and
                             thoracis:       side                          subcostal      rotatores make up
                             spines 4-6                                    aa., lumbar    the
                             vertebrae                                     aa.            transversospinal
                             above                                                        muscle group
                             origin

semispinalis,                                this group of                                these muscles
multifidus,                                  muscles                                      make up the
and rotatores                                provides                                     transversospinal
                                             rotational,                                  muscle group
                                             extension
                                             and lateral
                                             bending
                                             movements
                                            between
                                            adjacent
                                            vertabrae;
                                            they extend
                                            the head and
                                            neck


                                          Osteology of the Back

  Bone         Structure                Description                                  Notes

occipital                        the bone forming the           it articulates superolaterally with the parietal
                                 posterior surface of the       bones through the lambdoid suture,
                                 skull and posterior portion    anteroinferiorly with the temporal bone and
                                 of the skull base              anteriorly with the body of the sphenoid bone

            external occipital   a low process on the           it is an attachment site for the ligamentum
            protuberance         external surface of the        nuchae; the superior nuchal lines of the two
                                 occipital bone in the          sides meet in the midline at the external
                                 midline                        occipital protuberance; also known as: inion

            inferior nuchal      a low ridge that runs          it is an attachment site for deep neck muscles
            line                 transversely on the
                                 external surface of the
                                 squamous part of the
                                 occipital bone inferior to
                                 the superior nuchal line

            superior nuchal      a low ridge that runs          it is an attachment site the for the trapezius
            line                 transversely on the            and splenius mm.
                                 external surface of the
                                 squamous part of the
                                 occipital bone

            occipital condyle    a low, wide projection         paired; it articulates with the atlas
                                 from the inferior surface
                                 of the lateral part of the
                                 occipital bone



vertebra                         one of a series of irregular   a vertebra has two parts: the vertebral body
                                 bones that form the spine      and the vertebral arch; there are 33 vertebrae
                                                                total: 7 cervical, 12 thoracic, 5 lumbar, 5
                                                                fused to form the sacrum, 4 coccygeal;
                                                                features of a typical vertebra include: body,
                                                                pedicles, transverse processes, laminae,
                                                                articular processes, spinous process

            vertebral body       the largest part of the        it is shaped like a short cylinder; adjacent
                                 vertebra                       vertebral bodies articulate through a
                                                                symphysis

            vertebral arch       the ring of bone formed        the transverse processes and spinous process
                                 by the paired pedicles and     are attached to the neural arch; the neural
                                 paired laminae of the          arch protects the spinal cord
                               vertebra

            pedicle            short strong process that     paired; it connects the body with the
                               extends posteriorly from      transverse process; it is marked by superior
                               the posterolateral surface    & inferior vertebral notches;
                               of the vertebral body

            transverse         a lateral process the         a site for muscle attachment and rib
            process            extends from the junction     articulation
                               of the pedicle and the
                               lamina of the vertebra

            lamina             a broad flat plate of bone    paired; it is flattened markedly in the
                               located between the           anteroposterior direction; ligamenta flava
                               transverse process and the    span the interval between the laminae of
                               spinous process of the        adjacent vertebrae
                               vertebra

            articular          processes that project        two pair on each vertebra (superior and
            processes          inferiorly and superiorly     inferior); the superior articular processes of
                               from the junction of the      one vertebra articulate with the inferior
                               lamina and pedicle of the     processes of the adjacent vertebra through
                               vertebra                      synovial joints

            vertebral notch    a notch on the superior       the superior vertebral notch of one vertebra
                               and inferior surface of the   combined with the inferior vertebral notch of
                               vertebral pedicle             the adjacent vertebra forms the intervertebral
                                                             foramen

            intervertebral     an opening between the        adjacent vertebral notches form the
            foramen            pedicles of adjacent          intervertebral foramen; an opening for
                               vertebrae                     passage of the spinal nerve

            vertebral canal    a canal formed by the         it contains the spinal cord, meninges,
                               combination of the            epidural fat and the internal vertebral plexus
                               vertebral foramina of all     of veins
                               vertebrae

            vertebral foramen the opening formed by the when all vertebrae are articulated, the
                              body and the vertebral    combined vertebral foramina form the
                              arch                      vertebral canal

            spinous process    a posterior midline           an important site of muscle attachment
                               process arising from the
                               junction of the two
                               laminae of the vertebra

cervical                       the seven vertebrae of the    cervical vertebrae have the features of the
vertebrae                      neck                          typical vertebra plus all have transverse
                                                             foramina (for passage of the vertebral
                                                             artery); C2-C6 have bifid spinous processes;
                                                             cervical vertebrae have relatively small
                                                             bodies; several cervical vertebra are named:
                                                             atlas, axis, vertebra prominens

            atlas (C1)         the first cervical vertebra   atlas has no vertebral body, only anterior and
                                                             posterior arches; it articulates with the
                                                             occipital bone and the odontoid process of
                                                             the axis

            axis (C2)           the second cervical          the odontoid process (dens) projects
                                vertebra                     superiorly from its body; it articulates with
                                                             the anterior arch of the atlas



            vertebra            the seventh cervical         it has a long, non-bifid spinous process
            prominens           vertebra                     which is prominent at the nape of the neck,
                                                             hence its name

thoracic                        the 12 vertebrae             thoracic vertebrae have the features of a
vertebrae                       associated with the          typical vertebra plus they are characterized
                                thoracic region              by long slender spines that project inferiorly;
                                                             they have facets for articulation with ribs;
                                                             thoracic vertebrae have bodies of
                                                             intermediate size

            costal articular    small smooth areas at the    most thoracic vertebrae have 2 costal facets
            facet on the body   junction of the body and     on each side (one superior and one inferior);
                                the vertebral arch           the superior costal facet of one vertebra and
                                                             the inferior costal facet of the adjacent
                                                             vertebra both articulate with the head of the
                                                             same rib; also known as demifacets

            costal articular    a small smooth area on       it articulates with the articular facet on the
            facet on the        the transverse process of    tubercle of the rib
            transverse          the thoracic vertebra
            process

lumbar                          the 5 vertebrae located in   lumbar vertebrae have the features of a
vertebrae                       the lumbar region            typical vertebra plus they are characterized
                                                             by short, blunt spines that project posteriorly;
                                                             lumbar spines do not overlap making the
                                                             lumbar level a good one for spinal tap;
                                                             lumbar vertebrae are built strong and have
                                                             the largest bodies of all vertebrae

sacrum                          a triangular bone that is    it is formed by 5 fused vertebrae; the sacrum
                                the posterior skeletal       and two os coxae bones form the pelvis
                                element forming the
                                pelvis

            anterior sacral     openings on the anterior     there are four pairs; each transmits the
            foramina            surface of the sacrum        ventral primary ramus of the respective
                                                             sacral spinal nerve; branches of the lateral
                                                             sacral aa. and vv. reach the sacral canal by
                                                             passing through these openings

            posterior sacral    openings on the posterior    there are four pairs; each transmits the dorsal
            foramina            surface of the sacrum        primary ramus of the respective sacral spinal
                                                             nerve

            promontory          the anterior aspect of the   the body of the fifth lumbar vertebra sits on
                                body of the first sacral     the body of the first sacral vertebra; the
                              vertebra                      anterior longitudinal ligament attaches to the
                                                            promontory

          sacral canal        the opening in the center     it is the continuation of the vertebral canal at
                              of the sacrum                 sacral vertebral levels

          articular surface   the roughened area            this surface articulates with the ilium in the
                              located on the lateral        sacroiliac articulation; a synovial joint
                              surface of the sacrum

          body                the central portion of the    the body is equivalent to the bodies of the
                              sacrum                        other vertebra

          base                the superior surface of the   the base of the sacrum articulates with the
                              sacrum                        fifth lumbar vertebra through an
                                                            intervertebral disk

          sacral hiatus       an opening on the             it is a normal feature that results from the
                              posterior surface of the      failure of fusion of the laminae of the fifth
                              sacrum in the midline         sacral segment (and sometimes the fourth)
                                                            during development

          ala                 the lateral portion of the    paired; it projects laterally from the body of
                              sacrum                        the sacrum; it represents the fused costal and
                                                            transverse processes of the first sacral
                                                            vertebra

coccyx                        the most inferior portion     the coccyx results from the fusion of the four
                              of the vertebral column       coccygeal vertebrae; it may be a single bone
                                                            or the first coccygeal vertebra may be
                                                            separated from the other three; it articulates
                                                            with the fifth sacral segment; coccygeal
                                                            vertebrae are reduced in complexity, having
                                                            no pedicles, laminae or spines

scapula                       the bone of the shoulder      the scapula floats in a sea of muscles, so it is
                                                            difficult to fracture; it articulates with only
                                                            one bone - the clavicle at the
                                                            coracoclavicular and acromioclavicular joints

          superior border     the superior edge of the      the superior border of the scapula is marked
                              scapula                       by the scapular notch laterally

          medial border       the border of the scapula     it is an important site of muscle attachments
                              that runs from the            for the intermediate layer of back muscles
                              superior angle to the
                              inferior angle

          superior angle      the angle of the scapula      it is the attachment site for the levator
                              formed at the union of the    scapulae m.
                              superior and medial
                              borders

          lateral border      the portion of the scapula    it is an important site of muscle attachments
                              that runs inferomedially      for the teres major m., teres minor m. and the
                              from the infraglenoid         long head of the triceps brachii m.; it has a
                              tubercle to the inferior      groove for passage of the circumflex
                              angle                         scapular a.
inferior angle     the angle of the scapula     the inferior angle of the scapula often has a
                   formed by the union of       slip of origin of the latissimus dorsi attached
                   the medial and lateral       to it
                   borders

glenoid cavity     the articular surface        it articulates with the head of the humerus; it
                   located at the junction of   is deepened by a fibrocartilaginous rim
                   the superior and lateral     called the glenoid labrum
                   borders of the scapula

supraglenoid       a projection of bone         it is the attachment site for the tendon of the
tubercle           located superior to the      long head of the biceps brachii m.
                   glenoid cavity

infraglenoid       a projection of bone         it is the attachment site of the tendon of the
tubercle           located inferior to the      long head of the triceps brachii m.
                   glenoid cavity

spine              a heavy ridge that runs      it supports the acromion process; it divides
                   from the medial border of    the posterior surface of the scapula into a
                   the scapula to the           supraspinatous fossa and an infraspinatous
                   acromion process             fossa

scapular notch     a notch on the superior      it is bridged by the superior transverse
                   border of the scapula        scapular ligament; the suprascapular a.
                   located medial to the        passes superior to the superior transverse
                   attachment of the            scapular ligament and the suprascapular n.
                   coracoid process             passes inferior to it (Army goes over the
                                                bridge, Navy goes under the bridge)

coracoid process   a beak-like process that     it is the attachment site for the short head of
                   projects anteriorly from     the biceps brachii m., the coracobrachialis
                   the lateral end of the       m., the pectoralis minor m. and the
                   superior border of the       coracoacromial and coracoclavicular
                   scapula                      ligaments

acromion           a broad, flat process        it articulates with the clavicle through a
                   located at the lateral end   synovial joint (acromioclavicular joint)
                   of the scapular spine

supraspinatous     a broad depression           it is the site of origin of the supraspinatus m.
fossa              located superior to the
                   spine of the scapula

infraspinatous     a broad depression           it is the site of origin of the infraspinatus m.
fossa              located inferior to the
                   spine of the scapula
                                            Spinal Meninges

   Organ                Location/Description                                   Notes

meninges        three layers of connective tissue       meninges provide protection and nourishment of
                covering the brain and spinal cord;     the brain, brainstem and spinal cord
                dura mater, arachnoid mater, and pia
                mater

dura mater      outermost of the meningeal layers       "tough mother"; it is the most durable of the
                covering the brain and spinal cord      meninges and provides support and protection for
                                                        the brain and spinal cord; two types are described
                                                        which differ in structure: cranial and spinal

epidural space the space external to the sac of spinal the epidural space contains epidural fat and the
               dura mater within the vertebral canal internal vertebral plexus of veins which is
                                                       valveless (clinically relevant)

arachnoid       intermediate one of the three layers    arachnoid mater is a thin membrane which is
mater           of meninges                             pressed against the inner surface of the dura mater
                                                        by cerebrospinal fluid pressure; arachnids are
                                                        spiders and the arachnoid mater is so named
                                                        because it has a thin, web-like appearance

subarachnoid    the space between the arachnoid         subarachnoid space contains cerebrospinal fluid
space           mater and the pia mater                 and spider web-like filaments

pia mater       delicate membrane that lies on the      "delicate mother", it is the most delicate of the
                surface of the brain and spinal cord    meninges; this layer faithfully follows all surface
                                                        contours of the brain and spinal cord; pia mater has
                                                        2 specializations: denticulate ligament and filum
                                                        terminale internum

denticulate     a lateral extension of pia mater from   denticulate ligament attaches to the dura mater to
ligament        the spinal cord                         anchor the spinal cord; it forms a scalloped free
                                                        border; there are 2 (one on each side)

filum           thread-like extension of the pia mater filum terminale internum is best seen between
terminale       from the conus medullaris of the       vertebral levels L2 and S2; it becomes enclosed
                spinal cord                            within the filum terminale externum

coccygeal       thread-like extension of the dura       it attaches to the coccyx; also known as the
ligament        mater below the end of the dural sac    coccygeal ligament
                at S2

								
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