Lecture 6: Axial skeleton Test 2 Flashcards
function of spinal ligaments
limit motion
help maintain spinal curves
protect spinal cord and nerve roots
name all the ligaments found in the spine
ligamentum flavum
interspinous
supraspinous
inter transverse
ALL
PLL
apophyseal joint capsule
where can you find the ligaments flavum
anterior surface on lamina to posterior surface of one below
describe the characteristics of the ligaments flavum
yellow ligament
80% elastin, 20% collagen
thickest in lumbar region
describe the resistance and absorption given by ligaments flavum
constant modest resistance throughout wide range of flexion with 35% elongation
absorbs some intervertebral compression forces near end flexion
small but constant compression/stabilization in neutral
when is the fail range for the ligamentum flavum
ligament fails at 70% beyond its fully slackened length
describe the interspinous ligament
fill spaces between adjacent spinous processes
deep with more elastin bend with LF
superficial with more collagen blend with SS
fiber orientation varies by level
what is the function of the interspinous ligament
resists separation of adkjacent spinous processes (resists flexion)
describe the supraspinous ligament
attaches between tips of spinous process
more collagen in areas that resist flexion more strongly
very well developed in the cervical region: cranially it is the ligamentum nuchae
function of the supraspinous ligament
resist separation of the adjacent spinous processes (resist flexion)
what is the ligamentum nuchae (x5)
tough bilaminar fibroelastic tissue that attaches to cervical processes and external occipital protuberance
serves as a midline attachment for many muscles (i.e. trap, splenius capitis/cervicis)
gives some passive tension for extension support
can make palpation more difficult
describe inter transverse ligaments
poorly defines
thin, membranous
taut in colateral lateral flexion
slightly tight towards flexion
describe anterior longitudinal ligament (ALL); what does it look like, where does it attach, when is it taut/slack
long, strong, straplike - narrow at C/S and widens as it gets lower
attaches at the basilar part of the occipital bone and goes to the entire anterior surface of the vertebral bodies and then goes to attach to the sacrum
deeper fibers blend with and reinforce discs
taut in extension and slack in flexion
describe the posterior longitudinal ligament; what does it look like, where does it attach, where does it sit, when is it taut
continuous band of connective tissue
goes entire length o posterior surfaces of all vertebral bodies from C2 to sacrum
within vertebral canal, anterior to spinal cord
deep fibers blend and reinforce posterior Side of discs
broad cranially, narrows toward lumbar
taut with flexion
describe capsular ligaments of apophyseal joints; where does it attach, what type of fibers/why, reinforced by what, slack/taut when
attach to the entire rim of the facet surfaces
blend of elastin and collagen; tough to keep integrity of joint but flexible to allow arthrokinematics
reinforced by adjacent multifidus, ligamentum flava
slack in neutral, some fibers taut in each end ROM
describe the significance of knowledge of the ligament related to the axis of rotation
gives us information about how it moves/stretches
i.e in the sagittal plane any posterior ligament will stretch in flexion and any ligament anterior will stretch in extension
what is Panjabi’s neutral zone
there is a region of intervertebral motion around a neutral position that has little restraint from the passive spinal components (i.e. there is wiggle room between the two vertebrae without passive restraint)
used to quantify the amount of segmental instability
how is the neutral zone affected with injury
if neutral zone grows with disc degeneration or ligament injury there is more laxity/instability in the spine to control and more demands are thus placed on the stabilizing systems
with injury the vertebral motion pattern changes and influences the motion of the whole spine, potentially causing more pain and hyper mobility
what is spinal instability
loss of intervertebral stiffness that can lead to abnormal and increased intervertebral motion
what is the passive system of control (subset of Panjabi’s control system)
consists of bony structures, ligaments, joint capsules, discs, and passive portion of the musculotendinous units
thought to send feedback to the neural subsystem about joint positions and challenges to stability at the passive level
describe the active system of control (subset of Panjabi’s systems of control)
composed of muscles and tendons
describe the neural subsystem (subsystem of Panjabi’s) and when is it compromised
recives/transmits info from and to the other two systems (passive and active) to manage spinal stability
neuromuscular control can be compromised in patients with low back pain and must be considered in core stabilization program
describe core stability in relation to the neutral zone
can be viewed from segmental level or whole spinal level
when neutral zone is larger than normal (thus more slide, glide, and rotation between vertebrae) the spinal segment becomes unstable
describe the osteological features if the cervical vertebral column
smallest and most mobile
transverse foramina house vertebral arteries
describe the osteology of C3-C6 vertebrae
small/rectangular bodies
superior/inferior surfaces = curved/notched
superior portion = concave side to side with hooks (unicate processes)
inferior portion - concave ant/post; joint forms between recesses
forms medial wall of intervertebral foramen
how might nerves be “pinched” in the cervical spinal region
compression between 2 segments can impinge the greater spinal nerve
i.e. If there is an impingement between C4 and C5 vertebrae this would impinge the C5 spinal nerve root (because the cervical spinal nerves exit above the respective vertebrae)
** this is also why there is a C8 spinal nerve
describe the other osteological features of C3-C6 (x7)
pedicles are short and curved posterior-lateral
very thin laminae
larger vertebral canal
consecutive articular processes form a pillar with apophyseal joints
facets in joints are smooth/flat
superior facets face posterior/superior
inferior facets face anterior/inferior
describe the spinous and transverse processes of C3-C6
SP = short and some are bifurcated
TP= short lateral extensions with ant/post tubercles; unique to cervical spine and serve as attachments for muscles like anterior scalenes, elevator scapulae, and splenius cervicis
describe the important characteristics of the atlas (C1) (x6)
supports the head
no body/pedicle/lamina/spinous process
2 large lateral masses joint by anterior and posterior arches (superior concave facets to support cranium)
large transverse process
inferior articular facets are flat/slightly concave
anterior tubercle = attachment for ALL
describe important characteristics of the axis (C2) (x7)
large/tall body with dens (odontoid process)
dens = regid vertical axis o rotation for head/atlas
has superior articular processes to attach with C1
pedicles
short transverse processes
inferior articular processes face ant/inf
bifurcated spinous process (broad/palpable)
describe the unique characteristics of C7
largest cervical vertebrae
can have large transverse process and spinous process
can have a cervical rib (brachial plexus issue) off transverse process
key characteristics of T2-T7 (x10)
posterior directed pedicles
short/thick lamina
spinous process slanted down
more narrow vertical canal than cervical
larger TP (posterior laterally with costal facet)
superior articular facets face posterior
inferior articular fastes face anterior
apophyseal joints aligned in frontal plane
have costal demifacets
intervertebral foramina = location for spinal nerves
what are the atypical thoracic vertebrae
T1 = has a full costal facet (entire rib) and a Demi facet for rib 2; elongated SP
T10-12 = single full costal facet
how is rib 1 atypical
shorter/wider than others
only 1 facet
superior surface marked by 2 grooves that make way for subclavian vessels
how is rib 2 atypical
thinner/longer than rib 1
2 articular facets on head as normal
roughened area on upper surface where serratus anterior originates
how is rib 10 atypical
only 1 facet for corresponding vertebra (T10)
*T9 does not have T10 rib reach up to it
how are ribs 11 and 12 atypical
no neck
only contain one facet which is articulation for their corresponding vertebrae
what are the 3 functional components of intervertebral joints
TP/SP = mechanical levers that increase leverage of muscles/ligaments
apophyseal joints = guide vertebral motion
interbody joint = absorb/distribute load, greatest adhesion, axes or rotation, spacers, provide passage for nerves
describe the osteokinematics of intervertebral movement
movement at any one intervertebral junction is small
combined motion at different joints = larger angular motion
move in 3 cardinal planes
axis is at/near inter body joint
rotation reference point is anterior
describe the arthrokinematics of intervertebral joints
most facets are flat
approximation (compression), seperation/gapping, gliding
describe apophyseal joints
24 pairs total
plane joints
lined with articular cartilage
enclosed by synovial capsule (well innervated)
acts as mechanical barricade
how do the orientation of facets influence kinematics
horizontally oriented favor axial rotation
vertically oriented block axial rotation
describe the make up of an intervertebral disc
nucleus pulposus = pulplike gel mid to posterior aspect of disc; 70-90% water in youth
annulus fibrosis = outer ring
describe the nucleus pulposus
hydraulic shock absorbing system
dissipates/trasnfers loads across consecutive vertebrae
gel like
proteoglycans. and GAGs linked to core protein
thin type II collagen, small # chondrocytes and fibroblasts (synthesizes the proteins and proteoglycans)
why is a disc negatively charged by nature
results from charged groups on glycominoglycan (GAG) molecules on the PGs found in the extracellular matrix of the disc
describe the annulus fibrosis
15-25 concentric rings of collagen fibers
prevent distraction/shear/tortion
50-60% collagen (elastin in between rings of collagen that allows circumferential elasticity)
entrap/encase pulposus
outer layer contains disc only sensory nerves
describe vertebral endplates
relatively thin cartilaginous caps that cover most of the sup/inf surface of vertebral bodies
surface facing disc = fibrocartilage that binds directly to collagen in AF
surface facing bone calcifies cartilage- weakly affixed to bones
diffusion of O2 and glucose
outer rings of annulus fibrosis with vascular supply = limited healing at disc
what are some of the changes that take place along with the degeneration of a disc
reduced permeability = inhibited syntheses of proteoglycans
less proteoglycans = less water
less ability to absorb/trasnfer loads
doesn’t just happen with aging; also with excessive/abnormal loads
how is an IVD considered a “load sharing system”
biomechanics interaction between nucleus pulposa and annular rings
what happens to the endplates with compressible loads
push endplates inward to NP
describe how elastin and collahgen work to create a pressure distributer in Intervertebral discs
stretched rings of collagen and elastin create tension to resist and balance forces
the forces are then uniformly transferred to the vertebral bodies
once the force is gone the stretch is released and all structures return to normal
how are intervertebral discs viscoelastic
resist fast and strongly applied loads
less resistance is given to slow or lighter compressions
thus they are flexible at low loads and more rigid at higher loads
how does sustained, full lumbar extension affect discs
this reduces the pressure in discs and can allow water to be reabsorbed in the discs
describe the daily fluctuations that take place in the discs
1% height change during the day
supine is low pressure and allows water to “swell” disc and “refill”
during the day WB forces push water out of the disc
age changes can also affect; less ability to retain water as we get older (proteoglycan reduces)
what might give a dx of degenerative disc disease
loss of distinction of AF and NP with imaging
nuclear bulging
loss of disc space
not always symptomatic or loss of function
changes in discs often proceed what condition
osteoarthritis
what is spinal coupling
any movement of the spine in a plane is combined with an automatic and often imperceptible movement in another plane
what are the reasons/explanations for why spinal coupling occurs
muscle action
facet alignment
posture
ribs
stiffness
curve of spine itself
what can you/can’t you expect with spinal coupling patterns
there is varied and little consensus as to which coupling pattern is normal for different specific regions
in the middle and lower cervical spine there is a more consistent pattern = lateral flexion and ipsilateral rotation
describe the movement of the Atlanta occipital joint
movement of the cranium on the axis
convex condyles of the occiput and concave facets of the atlas
2 degrees of freedom: flexion/extension and lateral flexion
median joint of Atlanto-axial joint motions/characteristics
dens of C2 into the osseous ligamentous ring
horizontal stability is given by anterior arch of atlas and transverse ligament
2 synovial cavities
pivot joitn
describe the pair of apophyseal joints on the Atlanta axial joint
flat and close to the horizontal plane
2 degrees of freedom: rotation and flexion/extension
what is the tectorial membrane
on the AA joint
posterior to the transverse ligament
basilar (base of skull) and posterior longitudinal ligament attachments
what are the alar ligaments
on AA joint
tough fibrous cords 1 cm “check” ligaments
run side of the dens to lateral foramen magnum
describe the intracervical apophyseal joints
facets of C2-C7 like singles on a roof at a 45 degree angle
increased freedom of movement in all 3 planes
how much combined motion is present in the cervical region in the sagittal plane
120-130 degrees
how much extension is present in the cervical spine normally
80 degrees
how much flexion is found in the cervical spine normally
45-50 degrees of flexion
20-25% of total is at the OA/AA (upper cervical)
the remainder is from C2-C7
resting angle of cervical region in flex/ext
resting is 30-35 degree flexion
where is the restraint from in the cervical spine throughout flexion
ligamentum nuchae
interspinous ligamen
where are the compressive forces in flexion of the cervical spine
compressive forces on the anterior margin of AF
where are the restraints in the cervical spine during extension
from approximation apophyseal joints
where are the compressive forces in the cervical spine during extension
compressive forces on the posterior margin of the AF
how much flexion extension is present in the AA joint
15 degrees flex/ext
tilt of the axis
how much overall motion is present in the facets
90-100 degrees of overall motion
55-60 degrees extension
35-40 degrees flexion
average of 15 degrees for each segment
where is the greatest arthrokinematic motion in the cervical spine as well as the most common injury sights
greatest movement at C4-C6, also the sight for greatest spondylosis and hyper flexion injuries
what kind of motion is present in the horizontal plane at the AA joint
designed for rotation
35-40 degrees each direction
what kind of motion is present in the frontal plane of the cervical spine
35-40 degrees each side (most at C2-C7; 5 degrees at AO)
how does flexion affect the apophyseal joints and the intervertebral foramen
full flexion causes an “opening” of the apophyseal joint and an increased size of the intervertebral foramen
this can provide greater passage of the spinal nerve roots
what is the normal curvature of the thoracic spine? How stable is this area?
normal = 40-45 degrees of kyphosis
fairly stable (stabilized by ligaments)
