VC week 3 Flashcards
how many vertebrae in vertebral column?
regions?
when is this complete?
develops as 33, reduced to 24 + sacum & coccyx
cervical = 7 thoracic = 12 lumbar = 5 sacrum = 1 (5 fused) coccyx = 1 (4 fused)
sacral and coccygeal fusions do not start until 20, not completed until middle age
functions of vertebral column?
protects spinal cord
body flexibility
mobility (intervertebral discs)
cervical vertebrae?
features?
curve?
divided into?
7 vertebrae
smaller compared to other regions as bear less weight + distinguished by their great flexibility
lordotic curve
divided into 2 parts (atypical and typical) which differ anatomically and functionall
typical cervical vertebrae?
features?
C3 - C6
pic is superior view
features of typical cervical vertebrae?
- spinous process
- bifid
- projects posteriorly
- vertebral body
- composed of trabecular bone surrounded by thin layer of compact bone
- small - reflects amount of weight carried
- superior articular facet (zygapophyseal joint)
- in addition to articular processes
- flat and oval in shape
- superior facet projects backwards, upwards + medially
- Laminae
- bilateral, long + narrow
- forms majority of the arch & links transverse process with spinous process
- protrude posteromedially
- pedicles
- bilateral
- cylindrical bones that connect vertebral arch to the body
- short, protrude posterolaterally
- articular processes
- 4 = 2 superior and 2 inferior
- flattened bone which face superiorly + inferiorly respectively
- found at junction of pedicle + lamina
- project laterally on both sides
- transverse process and foramina
- has neural sulcus supplying pathway for spinal nerve
- anterior part = costal process (in front of foremen laterally)
- posterior part - true process (behind foramen laterally)
- one foramen in each process to allow passage of vertebral arteries, veins + nerve plexus to supply the brain
purpose of bifid cervical spinous process?
what about superficial muscles?
increases surface area for muscle attachments
due to their shortness, superficial muscles (e.g. trapezius + splenius capiits) attach to nuchal ligament instead of cervical vertebrae
cervical vertebral body morphological differences?
(sex, ethnic origin + age)
vertebral bodies + foramina significantly wider, more elongated + higher in males
african americans have wider, elongated vertebral bodies in C3-C5 than european americans
heights of C3 + C4 smaller in AA regardless of sex
cervical vertebral bodies become wider and more elongated with age (elongation more obvious than width)
also change shape with age (round → oval)
also reduction in height with age
no changes to vertebral foramen size with age
what does C1 articulate with?
Superior articular facet - occipital condyle of skull
inferior articular facet - lateral masses of C2
C1 anterior arch features?
anterior arch has anterior tubercle - for attachment of longus colli muscles and anterior longitudinal ligament
has fovea dentis for articulation with odontoid process of the axis
upper border = atlantooccipital membrane for attachment with occipital boen above
lower border = anterior atlantoaxial ligament for attachment with axis below
atypical vertebrae?
C1, C2, C7
C1 also called?
osteological features?
structure?
C1 = atlas
- ring-shaped
- no vertebral body (instead there are bilateral masses that bear weight from the skull)
- no spinous process
structure
- between each lateral mass, there is an anterior and posterior arch
- on lateral masses are the facet surfaces:-
- superior facet = upwards, deep curve, articulates with occipital condyle of skull
- inferior facet = downwards, flat, articulates with superior facet of C2
- transverse process = longer than other vertebrae, more lateral than any other transverse process of cervical spine
C2 also called?
osteological features?
C2 = called axis due to its function in rotating the head left and right (axis of rotation)
Dens = piece of bone that extends upwards from vertebral body + articulates with posterior surface of C1 anterior arch
has vertebral body (unlike C1)
has large bifid, spinous process (unlike C1)
bilateral masses = transmits weight
transverse processes = contain foramina transversarium, shaped like an L to permit lateral slanting of vertebral artery (remember C1 has lateral transverse foramen)
superior articular facets
inferior articular facets = positioned anteroinferiorly
thick pedicle + lamina
function C7?
called?
osteological features C7 vertebrae?
C7 is transition between highly flexible cervical spine + rigid thoracic
very similar to thoracic vertebrae
called “vertebral prominens” because of its spinous process (palpable)
atypical features
- spinous process = not bifid, longest out of all CV, multiple muscles attach here, positioned postero-inferiorly
- transverse process = very small transverse foramen (sometimes absent), contains accessory veins instead of vertebral artery
cervical spine joints?
cervical spine injuries?
76 individual joints
significant CSI:
- fracture
- dislocation/subluxation
- ligamentous tearing
functions cervical spine?
normal kinematics? - IMPORTANT
anchors head so eyes are parallel to ground (helps vestibular system in ear maintain balance)
provides motility - view our surroundings
muscle attachment
spinal cord - vertebral bodies protect SC + vertebral arteries
Kinematics
- flexion = 80-90*
- extension = 70*
- lateral flexion = 20-45*
- rotation = 90*
atlantooccipital joint? what does this mean?
articulatons?
surfaces lined with?
bilateral ellipsoid synovial joint between C1 and occipital condyle of skull
ellipsoid/condylar joints allow movement in 2 axes - AO joint can only assist in flexion + extension (limited lateral flexion)
- articulations = superior articular facet of C1 + occipital condyle of skull
- there is no IV disc between these surfaces, but articular surfaces are still lined with hyaline cartilage
why is there limited ROM for atlantooccipital joint?
due to deep shape of articular facets
- hinders translational movements of the head
- restrains anteriorly, posteriorly + laterally
- gives stability + balance (head wont fall off lol)
C1 atlantooccipital joint kinematics? (don’t confuse with cervical kinematics slide)
Flexion
- occurs in anteroposterior + transverse axis
- convex (inferior) surface of occipital condyles glide posteriorly over C1 articular facets
- results in occipital bone moving further away from C1 posterior arch in a nodding motion
- restricted to 5-10 degrees of flexion
extension
- occipital condyles slide anteriorly onto C1 articular facets
- decreased space between occipital condyles and arch of C1
- restricted extension of 10*
lateral flexion
- not a major movement
- limited to 5-8 degrees
- coupled (multiple movements) + double joint action
- contralateral movement of occipital condyle = anterior movement of one OC + posterior movement of other
structures associated with atlantooccipital joint stability?
significance?
articular capsule = thin, both AO joints covered, fibrous tissue with synovial membrane
ligaments = nuchal ligament, alar ligament, lateral atrlantooccipital ligament
primary stability:
- anterior atlantooccipital membrane (continuation of anterior longitudinal ligament) = fibrous tissue, anterior border of foramen magnum → upper border of anterior arch of C1
- = anterior LL provides additional stability
- posterior attlantooccipital membrane = spreads across posterior AO joint, posterior border foramen magnum → upper border of posterior arch of C1
- = significant landmark for vertebral artery and C1 nerve
craniovertebral joints?
AO joint and atlantoaxial joint
intervertebral discs cervical spine?
type of joint?
function?
no IV disc between C0-C1 or C1-C2
C3-C7 = symphysis joint links the iV discs
they are secondary cartilaginous joints
control ROM of the spine
ligaments of cervical spine?
anterior longitudinal ligament
lies anterior to vertebral body
tenses during cervical extension
posterior longitudinal ligament
lies posterior to vertebral body
stretches during cervical flexion
ligamentum flava
latin for yellow
connects laminae of each vertebrae
facilitates + controls flexion
ligamentum nuchae
extends from occipital protuberance + spreads across cervical spine
gives stability to head + neck - restricts flexion
also important muscle attachment site
CSI’s occur where?
mortality?
Ax?
Dx?
⅓ of CSIs occur in craniocervical junction (OA + AA)
death is usually certain
Ax = RTAs
Dx = CT + MRI
CSI’s occur where?
mortality?
Ax?
Dx?
⅓ of CSIs occur in craniocervical junction (OA + AA)
death is usually certain
Ax = RTAs
Dx = CT + MRI
AO dislocation types?
mechanism?
Type 1
common
ventral dislocation
type II
highly unstable
longitudinal distractions (upward force)
type III
rarest
dorsal dislocation
mechanism = hyperextension
trauma to posterior AO (tectorial) membrane
+ lateral flexion
C1 fracture Ax?
types?
axial loading (force directed through top of the head → through spine) due to RTA
jefferson fracture/burst fracture = anterior + posterior arches of C1 atlas
(occipital condyles press onto lateral masses causing breakage of A + P arches)
posterior arch fracture = related to hyperextension
anterior arch fracture = hyperflexion
lateral mass fracture = lateral flexion on one side of vertebrae
(note: burst + lateral mass fractures both involve rupture of transverse ligament)
ewrbe
A = jefferson fracture
B = lateral mass fracture
C = lateral mass fracture
atlantoaxial joint made up of?
movements?
why is it significant?
AA joint made up of 2 joints:-
median atlanto-axial joint (dens + transverse ligament)
lateral atlanto-axial joint (lateral masses of atlas + axis)
movements:
principal movement - axial rotation (atlas supports skull and facilitates this)
bi-axial movement nodding + shaking head by rotating around odontoid process (limited flexion, extension + lateral rotation)
this is the most mobile part of the spine
AA joint ligaments?
Odontoid process
- osteoligamentous ring = anterior arch of atlas
- transverse ligament = attached to atlas posteriorly, runs across posterior surface of odontoid process
(pic = OA is nodding, AA is shaking?)
what is a motion segment?
made up of?
also called?
-Smallest unit of the spine which has biomechanical characteristics i.e. smallest unit which allows movement
made up of only 2 adjacent vertebrae + the ligaments that connect them
also called the functional unit/building blocks of the spine
motion segment components?
2 adjacent vertebrae
Intervertebral disc
Facet joints between vertebrae (superior + inferior articular processes)
Soft tissues and ligaments
vertebral body function?
rim + centre?
vertebral foramen?
spinous + transverse processes?
vertebral body = load bearing
cortical bone rim = resistant to bending + torsion
cancellous bone centre = flexibility + structural support
vertebral foramen = protects spinal cord during movement
spinous + transverse processes = muscle attachment
zygapophyseal joint?
how does shape differ in spinal regions?
thus…
facet joint - between inferior articular process on superior vertebra and superior articular process of inferior vertebra
cervical + thoracic = plane surface (in cervical region allows flexion, extension, lateral flexion + rotation → in thoracic region allows lateral flexion + rotation)
lumbar = joints have curved surface which only allows flexion + extension
thus shape of facet joint restricts movement of the motion segment
IV disc functions? (3)
layers of IV disc?
how is IV disc bound to vertebral bone?
IV disc functions:
shock absorber
transmits mechanical load
allows + manages motion in motion segment
outer rim = anulus fibrosis (made of collagenous sheets called lamellae) - these sheets are strong but flexible = allows spinal column to bend
centre = nucleus pulposus, gelatinous which alllows absoprtion of water to help anulus fibrosis maintain its stiffness
IV disc bound to vertebral bone by the endplate
spinal ligament function? (3)
Allow motion without muscle
Protect spinal cord by restricting motion segment movement
Absorb energy and protect spinal cord during quick movements
A = sclerotomic segments seperated by less dense intersegmental tissue
B = condensation + proliferation of sclerotomal cells around notochord forming the IV discs
e.g. IV disc pathologies?
degenerated disc = tears in annulus fibrosis
bulging/prolapsed disc = annulus fibrosus still intact but is protruding into spinal column
erniated disc = nuclueos pulposus has protruded through annulus fibrosus into spinal column
MRI scan
image shows different stages of disc degeneration using MRI
A = normal disc
B-D = intervertebral disc starts to become darker → means disc has lost water content
E = thinning disc with osteophyte formation
x-ray
can also see osteophytes forming
…
CT scan shows a herniated disc in the lumbar region compressing the spinal nerves
movements of VC?
degrees of movements?
flexion
extension
axial rotation
lateral flexion
(lat flexion + rotation are associated movements, both take place with the other)
degrees of these movements between motion segments differ throughout the vertebral column = difference in the IV disc thickness and articular process position
movements + movements in motion segment
flexion + extension movements + forces?
flexion + extension occur as rotations in sagittal plane around lateral axis (see image)
flexion
nucleus pulposus migrates posteriorly due to compression of anterior annulus
(anterior compression forces)
extension
nucleus pulposus migrates anteriorly due to compression of posterior annulus
(posterior compression forces)
axial rotation forces + movements?
where does axial rotation occur?
coupled with?
rotation of vertebrae around longitudinal axis in transverse plane
the annular fibres that run in the same direction as the direction of movement = relaxed
the annular fibres that run in the opposite direction as the direction of movement = stretched
results in compression of nucleus pulposus
there is no axial rotation at lumbosacral junction + very small degrees in lumbar region
axial rotation + lateral flexion are coupled movements
lateral flexion movement + forces?
lateral flexion occurs as lateral rotation in frontal/coronal plane
flexing laterally to right side - right side of intervertebral disc is compressed + left side is stretched
flexing laterally to left side - left side of intervertebral disc is compressed + right side is stretched
axial compression force?
compressive forces increase from cervical vertebrae towards lumbar + sacral
compression causes pressure build-up within nucleus pulposus
as the nucleus is fluid-like it produces hydrostatic pressure which is isotropic - same in all directions
to distribute load of the force, inner + outer margins of annulus swell outwards, anteriorly, posteriorly and laterally
shear forces?
Experienced during actions like pushing or pulling
vertebrae in the motion segment “slide” + disc is displaced in the direction of the force is applied
can occur in the y axis (anteriorly/posteriorly) or in the x axis (laterally)
moments in spine?
torsional moments
occur in plane perpendicular to axis of intervertebral disc (i.e. Z axis)
causes twisting of spine
annular fibres in direction of torsion become stretched
bending moments
occur in plane parallel to axis of IV disc (i.e. X or Y)
Y axis = flexion/extension bending
X axis = lateral bending moment (opposite way round from image wtf)
e.g during flexion upper body weight x distance from spine = bending moment
