RA week 8 Flashcards
Functions of vertebral column?
Muscle attachment
mobility
protection
weight transfer
haematopoeisis
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Vertebral column curvatures?
Primary + secondary curvatures
- primary = kyphosis (embryo)
- secondary = lordosis
*
4 curvatures of VC?
development of curvatures
develop in response to use of the vertebral column
- in newborn = primary curvature
- holds up head = 2ry cervical curvature
- Crawl + stand upright = 2ry lumbar curvature
Components of vertebrae?
lumbar vertebrae shown
vertebral arch posteriorly - connected to body by pedicle
2 pedicles form laminae which unite to form spinous process
space created by vertebral arch + VB = vertebral foramen (spinal cord)
2 superior articular processes + 2 inferior
Inferior vertebral notch is much more pronounced
where is spinal cord found?
vertebral foramen → space created by vertebral arch + VB
C1: Atlas features?
No body or spinous process
ant + post arches, each with a tubercle
(i.e. ant and post tubercle, sites of attachment for muscles)
superior articular surfaces → occipital condyles
C2: Axis features?
Dens/odontoid process projects up from body
flat superior articular facets (allows Atlas to rotate)
Features of cervical vertebrae C3-C7?
Typical cervical vertebrae
- Body = uncinate process (ridges)
- Transverse process = foramen transversarium (vertebral arteries), anterior + post tubercles with groove on superior surface for spinal nerve in between
- Spinous process = bifid
Thoracic verebrae features T1-T12?
Costal facets for articulation of ribs (on body + transverse process)
nearly vertical articular facets directed posteriorly (sup.) + anteriorly (inf.)
long sloping spinous processes
What is the significance of arrangement of articular facets in thoracic spine?
nearly vertical articular facets directed posteriorly (sup.) + anteriorly (inf.)
allows rotation
Lumbar vertebrae features?
significance of processes?
massive kidney-shaped body
accessory process on each transverse process
mammillary process on each sup. articular process
articular facets directed posteromedially (sup) + anterolaterally (inf) - so essentially grip vertebrae above
mammilary + accessory processes are sites of muscle attachment
arrangement of articular facets in lumbar region?
significance?
superior articular facets = posteromedially
inferior articular facets = anterolaterally
allows flexion + extension but very little rotation
spinous process lumbar vertebrae?
quadrilateral structure
Sacral vertebrae?
5 fused vertebrae
anterior sacral foramina - allow passage of anterior rami of sacral spinal nerves
more features than smooth anterior surface
auricular surface for articulating with the ilia
posterior sacral foramina for passage of spinal nerves
coccygeal vertebrae?
Co1 - Co4 fused
small and triangular
4 fused vertebrae
coccygeal cornu articulate with the sacrum
joints between VB?
Articular processes?
between VB = IV discs (2* cartilaginous)
between articular processes = zygapophysial joints (plane synovial)
Iv disc function?
structure? - related to function?
V important in allowing movement of the VC
Annulus fibrosis on outside + gelatinous centre called nucleus pulposus
nuecleus pulposus allows IB disc to deform + accommodate movement
muscles of the back divided into?
extrinsic + intrinsic
extrinsic further subdivided into superficial and intermediate
- superficial = connect to appendicular skeleton
- intermediate = superficial respiratory muscles
superficial extrinsic muscle function?
examples?
Involved in movement of upper limb + upper limb girdle:-
trapezius
latissimus dorsi
rhomboid major
rhomboid minor
levator scapulae
trapezius attachment?
from base of skull (medial ⅓ superior nuchal line), nuchal ligament, spinous processes C7-T12 to → → lateral clavicle, acromion + spine of scapula
latissimus dorsi attachments?
from spinous processes T7-T12, thoracolumbar fascia, iliac crest and lower 4 ribs to → edge of bicipital groove of humerus (i.e. anterolateral aspect of humerus)
(like trapezius, fibres converge before distal attachment)
trapezius muscle function?
Innervation?
rotate scapula so glenoid cavity points more superiorly, allowing greater degree of abduction of upper limb
retract scapula (middle fibres)
Innervation = spinal accessory (XI)
action of latissimus dorsi?
innervation?
extension, adduction + medial rotation of arm
important in things like climbing
innervation = thoracodorsal nerve (C6, C7, C8)
bottom right is showing muscular attachment of latissimus dorsi in anterolateral aspect of humerus
tendon comes from posteriorly to wrap around anteriorly at bicipital groove
if reflect trapezius muscle you will see?
rhomboid major + minor
levator scapulae
rhomboid major attachments?
minor?
level of division?
innervation?
function?
major = sp. processes T2-5 to → medial border scapula (spine to inf. angle)
minor = nuchal ligament, sp. processes C7, T1 to → medial end of spine of scapula
(so divided at level of spine of scapula)
innervation = dorsal scapular nerve (C4, C5)
retract the scapula
levator scapulae located?
attachments?
function?
Innervation?
largely located within the neck
from posterior tubercles transverse processes C1-C4 to → medial border of scapula above spine
function = elevates scapula
innervation = cervical nerves C3, C4 + dorsal scapular nerve (C4, C5)
intermediate extrinsic muscles of the back?
examples?
secondary muscles of respiration:
serratus posterior superior
serratus posterior inferior
serratus posterior superior attachments?
Innervation?
function?
superior = nuchal ligament, spinous processes C7-T3 to → superior borders ribs 2-4
innervation = intercostal nerves 2-5
assists in raising upper ribs
inferior = sp. processes T11-L2 to → inferior borders ribs 8-12 near angle
innervation = anterior rami T9-T12
function = assist in lowering lower ribs
superficial intrinsic muscles of the back?
attachments?
splenius capitis (looks a bit like a bandage) + cervicis
nuchal ligament and sp. processes C7-T4 to →
- capitis → mastoid process and lateral ⅓ sup. nuchal line
- cervicis → tubercles of transverse processes C1-C4
intermediate intrinsic muscles of the back?
layers?
common proximal attachment?
Erector spinae muscles
arranged in 3 columns from lateral to medial:
iliocostalis, longissimus, spiinalis
common porximal attachment = posterior iliac crest, posterior sacrum + SI ligaments, sp processes of sacral + lower lumbar vertebrae, supraspinous ligament
iliocostalis parts?
attachments?
lumborum, thoracic, cervicis parts
common proximal attachment → angles of lower ribs, cervical transverse processes
longissimus parts?
attachments?
thoracis, cervicis, capitis parts
common proximal attachment → ribs (between tubercles + angles), thoracic and cervical transverse prcoesses, mastoid process
spinalis parts?
attachments?
often…?
thoracis, cervicis, capitis parts
common proximal attachment → upper thoracic sp. processes + cranium
often poorly developed
semispinalis parts?
attachments
thoracic, cervicis and capitis parts
transverse processes C4-T12 → occipital bone (capitis), thoracic + cervical sp. processes (thoracic + cervicis)
multifidus thickest?
attachments?
rotatores developed?
attachments?
functions?
multifidus:
- thickest in lumbar region
- fibres pass superomedially from transverse processes → to sp. processes 2-4 vertebrae above
rotatores:
- well developed in thoracic region (i.e. rotation most possible in thoracic region)
- fibres pass superomedially from transverse process → to junction of lamina + transverse process 1-2 vertebrae above
both are important in rotational movements of the VC
thickest in lumbar region
levator costarum found where?
interspinale?
intertransversari?
functions?
attachments?
levator costorum = in thoracic region
raises ribs
transverse process → upper border rib
Interspinale = well developed in cervical and lumbar regions
between adjacent spinous processes
Intertransversari = well developed in cervical + lumbar regions
between transverse processes of vertebrae
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thoracolumbar fascia extends from transverse processes towards anterior abdo wall muscles
also muscles of posterior abdo wall
posterior aspect of middle thoracolumbar fascia = intrinsic muscles of back
anterior longitudinal ligament found?
attachments?
layers?
function?
anterolateral aspect of vertebral bodies
skull base → sacrum
3 layers of dense collagen fibres
- deep fibres bind adjacent vertebrae together
- superficial fibres span multiple segments
limits extension (it is the only ligament that does this)
posterior longitudinal ligament found?
compared to anterior ligament?
attachments?
what is located between ligament + surface of the bone?
functions?
found within vertebral canal on posterior aspect of VBs
much narrower than anterior longitudinal ligament
C2 → sacrum
attached mainly to IV discs + vertebral margins
fat + vessels located between ligament + bone surface
functions = limits flexion (weakly) + prevents herniation of IV disc
ligamenta flava singular?
found?
made up of?
functions?
singular = ligamentum flavum
connect laminae of adjacent vertebrae
made up of strong elastic fibres
functions:
helps maintain curvatures
reinforce wall of vertebral canal posteriorly
limit flexion
ligaments of spinous and transverse processes?
found?
function?
Interspinous ligaments
- connect adjacent spinous processes
- thin, weak, membranous
supraspinous ligament
- joins tips of spinous processes
- C7 → sacrum (isn’t found above C7 due to nuchal ligament)
- tough, cord-like
intertransverse ligaments
- between adjacent transverse processes
- cervical = scattered fibres
- thoracic = fibrous
- lumbar = membranous
Interspinous + supraspinous limit flexion
Nuchal ligament?
attachments?
continuous with?
functions?
thickened fibroelastic tissue
external occipital protuberance, posterior border foramen magnum, spinous processes C1-C7
continuous with supraspinous ligament
functions:
muscle attachment
limits flexion
Spinal cord spans?
enlargements?
naming of spinal nerves?
foramen magnum → L1/L2 (medullary cone)
cervical enlargement C4-T1 (nerves to UL)
lumbosacral enlargement L1-S3 (nerves to LL)
cervical spinal nerves named after vertebrae below (exception C8) - emerge above vertebrae of the same number
T1 - Co1 named after vertebrae above - emerge below vertebrae of same number
cauda equina?
filum terminale? found?
cauda equina = lumbar + sacral roots extend below end of spinal cord
filum terminale = remnant of caudal part of spinal cord
extends from tip of conus medularis to coccyx
how do cauda equina and filum terminale arise?
at 3 months spinal cord and VC will be same length
by 5 months much more rapid growth of VC than spinal cord - root of 1st sacral nerve has had to lengthen
in newborn, spinal cord ends at level of L3 - growth continues in childhood so ends at L1/L2
blue indicates the pia covering the spinal cord
meninges attached to sacrum so as spinal cord moves upwards =
thin remnant of pia called filum terminale
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spinal meninges continuous with?
what are they?
spinal nerve?
continuous with meninges covering the brain
- spinal dura mater (superficial, toughest)
- spinal arachnoid mater
- spinal pia mater (deep)
meningeal coverings will extend along initial portion of the spinal nerve
spinal dura mater?
attachments?
dural root sheaths?
tough outer covering
attached to coccyx inferiorly by filum terminale
lateral extensions of spinal dura cover nerve roots as dural root sheaths
between dura mater and bone of VC?
contains?
epidural space
contains internal vertebral venous plexuses + epidural fat
spinal arachnoid mater?
what connects it to pia mater?
subarachnoid space contains?
enlargement?
delicate membrane lining dura (looks like spider web hence the name)
arachnoid trabeculae connect arachnoid to pia
subarachnoid space contains CSF
enlarged around conus medullaris to form lumbar cistern (L2-S2) - this is where you would do a lumbar puncture i.e. below level of spinal cord
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can see dural root sheath
when open dura (right) can see spider web-y arachnoid mater
pia mater not visible as distinct layer but as shiny surface of spinal cord
spinal pia mater covers?
denticulate ligaments?
found?
function?
covers spinal cord, nerve roots + spinal blood vessels
denticulate ligaments - run on either side of spinal cord between posterior + anterior nerve roots
found between ant + post roots of spinal nerve, will pierce through arachnoid and anchor in the dura
suspend cord in dural sac
arterial supply spinal cord?
found?
supported by?
what supply nerve roots?
anterior spinal artery (x1)
posterior spinal artery (x2)
run longitudinally from medulla oblongata to conus medullaris
supported by medullary segmental arteries (from trunk i.e. intercostal/lumbar arteries)
radicular arteries supply nerve roots
venous drainage of the cord?
drain into?
3 anterior + 3 posterior spinal veins
drain into medullary (segmental) and radicular veins
join internal vertebral venous plexuses in epidural space
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midline sagittal section through VC
can see internal vertebral venous plexus in epidural space
receives blood from vertebral bodies + spinal cord
will anastomose with anterior internal venous plexus + posterior
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Photograph A shows the posterior body wall after removal of the skin from the back. Some superficial fascia and fat are still adherent to the muscles.
Photograph B shows the same individual with the majority of this fatty tissue removed to expose the superficial muscles of the back. The scapulae can also be identified, though they are still covered in connective tissue and muscle at this stage of the dissection. This photograph shows the large trapezius muscles that attach to the occipital bone of the skull, to the scapula and to the vertebra. It has fibres that run in several different orientations which allows it to elevate, depress, retract and rotate the scapula relative to the body wall. Trapezius is the odd one out of the superficial muscle layer as it is innervated by a cranial nerve – CNXI the spinal accessory nerve.
Latissimus dorsi is the other prominent superficial muscle of the back. Photograph C shows the large, thin muscle sheet of latissimus dorsi as it passes between the lumbosacral fascia, around the lateral surface of the thorax and abdomen before inserting into the humerus. Although the muscle forms a thin sheet, it has a relatively large surface area allowing the weight of the body to be raised upwards towards the arms during chin-ups or climbing. Latissimus dorsi is innervated by a nerve from the brachial plexus – the thoracodorsal nerve.
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Photograph A shows trapezius lying between the vertebrae and the scapula. These fibres of trapezius act to retract the scapula (pull it towards the midline). If these fibres are sectioned, then the rhomboid muscles are visible. This is shown in photograph C – rhomboid major and immediately above it rhomboid minor pass between the vertebrae and the scapula. They also act to retract the scapula. During dissection, these muscles often appear as one sheet of muscle, with very little gap between the inferior border of rhomboid minor and the superior surface of rhomboid major. The rhomboids are innervated by the dorsal scapular nerve from the brachial plexus.
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Photograph A shows latissimus dorsi, if this muscle is sectioned and reflected then a much smaller muscle can be seen. Photograph B shows the thin and fibrous serratus posterior inferior muscle highlighted by a red plastic strip. Serratus posterior inferior is innervated by the anterior rami of T9 to T11 and the subcostal nerve (T12). Serratus posterior superior is not shown here but is innervated by T2 to T5 intercostal nerves. This means than none of the superficial muscles of the back are innervated by dorsal rami nerves – even though they are on the dorsal (posterior surface) of the body.
The next layer of muscles – the intermediate muscles of erector spinae and the small deep muscles of the back are supplied by nerves from the dorsal rami, as is the skin of the back. As you dissect down to the erector spinae you may find branches of the dorsal rami piercing through the muscle to reach the superficial fascia and skin. This is shown in photograph C where the nerves have been highlighted by a red plastic strip.
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This slide shows the intermediate muscle layer of the back – the erector spinae. These muscles appear to be one interconnected mass but can be divided into 3 muscle blocks. Each muscle can also be given the term ‘capitis’, ‘cervicis’, ‘thoracis’ or ‘lumborum’ depending on which part of the vertebral column it is related to.
Photograph A shows iliocostalis (shown by the red plastic strip), the most lateral of the erector spinae. Photograph B shows longissimus and photograph C spinalis (shown by the red plastic strip). All of the muscles extend the back and help to control flexion of the trunk. All of the erector spinae are innervated by the dorsal rami of the spinal nerves.
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Trapezius is the most superficial muscle that covers the posterior surface of the neck. If it is reflected then splenius capitis becomes visible (as shown in photograph A). On the same level as splenius capitis but in a more inferior position in the neck is splenius cervicis (shown by the red plastic strip in photograph B). If splenius capitis and cervicis are reflected then semispinalis capitis becomes visible (as shown in photograph C). There are deeper muscles in the suboccipital triangle of the neck posterior to semispinalis muscle but these muscles will be described later during dissection of the head and neck. The splenius capitis and cervicis and semispinalis capitis muscles act to extend the head or neck and allow lateral flexion of the neck, they are innervated by the dorsal rami nerves.
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This slide shows the deeper muscles of the back. Multifidus is shown by the red plastic strips in photographs A and B – it is easier to identify in the lumber region (photograph B) as there is more muscle mass in this area.
There are many deep muscles such as the interspinales(between the spinous processes of the vertebrae) and intertransversarii (between the transverse processes of the vertebrae). These are very small, as is rotatores(shown in photograph C) and levatorescostarum(shown in photograph D) and are not as easy to identify as the other muscles of the back. They act to provide small movements that assist in lateral flexion, rotation or extension of the back and are supplied by the dorsal rami nerves.
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Photograph A shows the right side of the back with much of the muscular tissue removed. If the posterior bony parts of the vertebral canal are removed (a laminectomy) the duralsheath surrounding the spinal cord can be seen. This is shown in photograph B.
Photograph C shows the dura mater surrounding the spinal nerves as they exit the spinal canal (shown by red plastic strips).
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If the dura is opened, then the neural tissue becomes visible. Photograph A shows the thin, shiny arachnoid lying inferior to the dura, the pia mater adheres to the nerves themselves. The spinal cord and nerves have become soft and pink/purple in colour due to the Thielembalming fluid. A spinal nerve can just be seen passing away from the cord in photograph A.
Photograph B shows the end of the spinal cord, which in adults is at vertebral level L1 to L2. The cord splits into the nerves of the cauda equina at this level and the end of the cord can be seen to form a medullary cone as it does so.
