Anatomy - The Back

ribs (bony structures that articulate with vertebral column)

-12 thoracic vertebrae articulate with ribs

Spinal Cord and Meninges

-Meninges: covering of the spinal cord with 3 layers as follows-> -dura mater "tough mother": outermost, leathery connective tissue covers spinal cord and brain, dorsal and ventral roots as they enter the intervertebral foramen and spinal ganglia -arachnoid mater: intermediate layer of meninges which has a 3d appearance, wispy and trabeculae span space, subarachnoid space is filled with cerebrospinal fluid (CSF) -pia mater: very thin and intimately invest blood vessels, dorsal/ventral roots and entire surface of spinal cord and brain -meninges extend as a "sleeve" into the intervertebral foramen, covering spinal ganglia before blending into *epineurial connective tissue that inverts peripheral nerves, anchors at bone of sacral hiatus

Epidural Anesthesia

-administered to the space outside of the lower dural sac into the epidural space->affects spinal nerves S2-Cox1 which lie outside main dural sac (remember dura mater ends at S2) -needle is inserted through sacral hiatus -also possible to administer trans-sacral through lower sacral foramina

Transversospinalis muscle group

-below erector spinae muscles -seen in grooves between transverse processes and spines of vertebrae. their course is superior and medial. -origin: transverse processes -insertion: vertebral spinous processes -3 muscles from superficial to deep: semispinalis, multifidis, rotatores (send mom roses) -extend and rotate the vertebral column (and head)

skull (bony structures that articulate with vertebral column)

-called atlanto-occipital joint -occipital condyles: articulate with the atlas, superior and inferior nuchal lines of occipital bone, mastoid process of the temporal bone

Triangle of auscultation

-space between the inferior border of trapezius and superior border of latissimus dorsi for optimal auscultation of thoracic sounds(have patient abduct scapula or put hands together and and lean forward to open up)

Denticulate ligaments

-specialized pia mater -located midway between each set of dorsal and ventral rootlets -typically found only above T12 level of vertebral column

Distal end of the spinal cord

-spinal cord ends in cone shaped structure called the conus medullaris (L1 vertebral level) -inferior to that, dorsal and ventral nerve roots that are within the vertebral column and still heading inferiorly to exit points form the cauda equina "horse's tail" -the dural sac which covers the spinal cord and cauda equina end at S2 level of vertebral column

Extrinsic back muscles

-superficial on back -move upper extremities or involved in respiration -trapezius, latissimus dorsi, rhomboid major, rhomboid minor, levator scapulae, posterior and inferior serratus

Filum terminale

-tapering of the pia mater past the conus medullaris into a string: the **filum terminale internum -lies among caudal dorsal and ventral nerve roots which form the cauda equina, distinguishable in lab by its very white shiny color -at inferior ending of dural sac S2, filum terminale picks up a dural covering and is then called **filum terminale externum

herniated disk concepts

-tear or weakness in annulus fibrosis causes bulging out of nucleus pulposus, usually posterolateral, can compress spinal nerves *usually at L4-L5, L5-S1 and, C5-6 or C6-7 *second number rule, nerve affected by disk prolapse (in cervical and lumbar) is the second number in disk name

Latissimus Dorsi

Origin: iliac crest, spines of T7-L5, thoracolumbar fascia, inferior 3-4 ribs Insertion: floor of intertubercular (bicipital) groove of humerus Nerve: thoracodorsal nerve Function: adducts, extends and medially rotates the humerus (e.g. power stroke of swimmer)

Splenius Capitis

Origin: ligamentum nuchae, spines of C7-T3 Insertion: mastoid process of temporal bone and lateral part of occipital bone Nerve: dorsal rami (no name) Function: extend head (together with cervicis), acting alone laterally tilts head

Rectus Capitis Posterior Major/ Minor

Origin: minor=atlas (C1), major=axis (C2) Insertion: occipital bone Nerve: dorsal ramus C1 (suboccipital nerve) Action: extend head and laterally rotate head

Trapezius

Origin: occipital bone, nuchal ligament, spines of thoracic vertebrae Insertion: spine of scapula, acromion, lateral clavicle Nerve: cranial nerve XI Function: elevates, retracts and superiorly rotates scapula (needed for full abduction of the arm)

Oblique Capitis Inferior

Origin: spine of axis (C2) Insertion: transverse process of atlas (C1) Nerve:Dorsal Ramus C1 (suboccipital nerve) Action: extend head and laterally rotate head

Splenius Cervicis

Origin: spines of T3-T6 Insertion: transverse processes of upper 3-4 cervical vertebrae Nerve: Dorsal rami Function: extend the neck (together with capitis), acting alone laterally tilts the neck

Oblique Capitis Superior

Origin: transverse process atlas (C1) insertion: occipital bone Nerve: Dorsal Ramus C1 (suboccipital nerve) Action: extend head and laterally rotate head

Levator Scapulae

Origin: transverse process of C1-C4 Insertion: scapula at superior angle Nerve: dorsal scapular nerve Fx: elevates scapula *shrug shoulder*

Rhomboid Major & Rhomboid Minor

Origin: vertebral spine; minor from C7-T1, major from T2-T5 insertion: medial border of the scapula nerve: dorsal scapular nerve Function: adduct and rotate scapula

Spinal Curvature Conditions

kyphosis: (hump back) excessive thoracic curvature scoliosis: excessive lateral curvature lordosis: (sway back) excessive lumbar curvature

Craniovertebral joint ligaments*(draw it)

must include: cruciform ligament (ID transverse ligament and longitudinal fascicles), alar "check" ligament of the dens lying deep to the cruciform ligament *clinical note: these ligs stabilize articulation of dens with anterior arch of atlas, if these ligaments rupture-> dens is driven into cervical spinal cord-> instant death (phrenic nerve innervation cut off)

ligaments of the spine, cervical (draw it)

must include: nuchal ligament, supraspinous ligament,, interspinous ligament, anterior longitudinal ligament

posterior view of vertebrae (draw it)

must include: pars interarticularis (are between superior and inferior articular processes) *clinical note: fractures here can cause misalignment aka spondylolysis

Inferior region of vertebral column( draw it)

must include: sacrum (sacral canal, sacral foramina, sacral hiatus) and coccyx

Parts of a typical vertebrae (draw it)

must include: vertebral body, pedicles, lamina, transverse process, spinous process, superior and inferior articular facets and, vertebral foramen

lateral view of vertebral articulations (draw it)

must include: zygapophysial joint between the inferior and superior articular processes, intervertebral disk

Numbering scheme and relationships of spinal nerves, vertebrae and intervetebral disks

-23 total disks, 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal pairs (C1 and C2 don't have a intervetebral disk) -cervical nerves leave above their same numbered vertebra (exception is C8, which leaves at C7-T1) -thoracic and lumbar leaves below same numbered vertebra

Dermatome Landmark names

-C2 dorsal ramus - back of head -C3-C4 - neck and top of shoulder -C5-T1 - upper extremity -C7 - middle finger -C8 - little finger -**T4 - nipple line -T6- bottom of sternum -**T10 - belly, umbilicus -T12 - pubic bone -L1-S2 lower extremity -S2-Cox1 are perineal -S2-S3

Rotatores

-cross 1 entire vertebrae -origin: transverse process -insertion: longus=spinous process of superior vertebra, brevis=base of spinous process immediately superior *best studied in diagrams and not in lab

scapula

-does NOT directly articulate with vertebral column -superior angle is at T2 -inferior angle is at T7 -acromion is the palpable endpoint of shoulder -coracoid process faces anteriorly

Intrinsic ("True") Back Muscles

-extend the vertebral column/head -rotate the vertebral column/head -**all innervated by dorsal rami of spinal nerves -Includes: Splenius Muscles (superficial) , Erector Spinae Muscles (intermediate), Transversospinalis Muscles (deep)

Length of spinal cord

-in adults: from medulla oblangata of brain stem to L1-2 intervertebral disk level -in 6 mo fetus: spinal cord goes to S1 because neurons do not divide after birth, cord occupies relatively less space as development proceeds

Lumbar puncture

-inside the dura mater but outside of the spinal cord -done at the highest point of the iliac crest, usually L3-L4 or L4-L5(for C-section anesthetic) -subarachnoid space is common point for removing CSF or introducing drugs (such as imaging fluids for myelography) -same landmarks for anasthetic agents -spinal anesthesia OR spinal tap

Suboccipital muscles

-obliquus capitis superior -obliquus captis inferior (misnamed inserts in vertebrae) -rectus capitis posterior minor -rectus capitis posterior major -innervated by suboccipital in C1 and greater occipital in C2 (solely sensory and no motor) -vertebral artery is deep within floor of this structure -muscles of suboccipital region extend and rotate head

Spinal arteries

-occur cervical level when vertebral arteries pass these branches on their way up to meet at the basilar arter -nourishes the spinal cord Branch off from the vertebral arteries as follows-> -anterior spinal artery: 1 big artery, lies in the anterior median fissure of the spine and supplies the anterior 2/3 of the spinal cord -posterior spinal arteries 2 that run parallel; the paired posterior spinal arteries supply the posterior 1/3 portion of the cord radicular and segmental arteries as follows: -contribute to spinal cord arterial tree at all levels. arise from spinal branches of vertebral, deep cervical, ascending cervical, posterior intercostal and, lower levels from lumbar and sacral arteries *the biggest segmental artery is the 'great radicular' because it branches from inferior intercostal artery and nourishes cord

Spinal cord segment

-portion which gives rise to a given pair of ventral roots and which receives a pair of dorsal roots -grey matter=butterfly shaped portion, contains neuron cell bodies in the spinal cord -white matter=contains the ascending and descending axons, most of them myelinated -anterior side of the spinal cord has a deep midline fissure (anterior median fissure) -upper levels of the cord have more white matter because of many descending axons -lower levels of cord have more grey matter since regions contain neurons that innervate extremities

Myelogram

-replaced by MRIs in the USA -obtained by injecting radio-opaque dye into the Subarachnoid space using lumbar puncture route prior to x-ray

Vertebral Arteries in Cervical Region

-right and left vertebral arteries arise from subclavian arteries and ascend posterior side of neck through holes in transverse processes of cervical vertebrae AKA foramen transversarium -enter the cranial cavity via foramen magnum->branch to anterior and posterior spinal arteries-> converge to basilar artery *key arterial trunk of the brain

ligamentum flava

-run between lamina, covers most space between these vertebral regions. yellowish. during flexion, vertebra tend to move apart and ligementa flava stretches to accomodate *clinical note, commonly damaged in rear end accidents because of violent hyperextension, potential for injuring spinal cord (check your headrest!)

posterior longitudinal ligament

-runs along the posterior side of vertebral bodies -actually anterior to the spinal cord

Erector Spinae Muscle Group

-runs longitudinally from sacrum to skull. as a whole *extends* the vertebral column iliocostalis: origin=iliac crest and sacrum, insertion=passes superior to ribs lonigissimus: origin=inferior transverse processes, insertion=superior transverse processes spinalis: closest to midline (I love spaghetti) all innervated by dorsal rami

Unique bone schemes of C1 and C2

C1: Atlas, has no spines but has anterior and posterior arches, large articular facets for articulation with the occipital condyles for the skull. C2: Dens, toothlike process, articulates with the homologue of the "body" of atlas forming atlanto-axial joint

Surface Landmarks

C7 (vertebrae prominens): base of neck T2 vertebral level: superior angle of the scapula T7 vertebral level: inferior angle of the scapula Median furrow: located on the midline superficial to verterbral spines; separates erector spinae on either side. **L4 spinal level: line drawn here are high points of the iliac crest S2 verterbral level: "dimples of lower back". inferior extent of dural sac. Superior end of intergluteal cleft: superficial to sacral hiatus

different types of vertebrae

Cervical: distiguinshed by hole in transverse processes through which vertebral artery passes. C1 (atlas) and C2 (axis) are unique Thoracic: specialized with articulation regions for ribs Lumbar: large with heavy bodies, have an extra set of processes (mammillary processes)

Clinical picture of disk prolapse

Lumbar level: acute with acute back pain and sciatica-lower leg and foot-> spasma of back mainly on prolapsed side Cervical disk prolapse: pain is reported in upper extremity posterior protrusions of disks: rare and act like tumors in vertebral canal and compress spinal cord if they occur above the cauda equina level of cord (causes paralysis and anesthesia) *dehydration and disk degeneration leads to "shrinking" or shortening of people with age

Semispinalis muscle divisions

semispinalis thoracis/ cervicis: -origin: transverse processes of thoracic vertebrae -insertion: higher spinous processes semispinalis capitis: -origin: tips of transverse processes of upper thoracic and lower cervical vertebrae -insertion: occipital bone between nuchal lines