Vertebral Column Flashcards
Vertebra Body
-weight bearing structure
-Cancellous (inner) and Cortical (outer)
Neural Arch - Pedicles
-increase in size caudally (cervical -> lumbar)
-Transmit forces from posterior elements to the vertebral body
-Defines size/shape of the vertebral canal
Post Elements of Neural Arch
Lamina
- “roof” to protect spinal cord
- Transfer forces through pars interarticularis from the spinous and articular processes to pedicles
Post Elements of Neural Arch
Articular Processes
- connect with the vertebra above/below
- Facet Joint = Zygapophyseal Joint (ZAJ)
- Resist shear, compression, tensile and torsional forces - transmits forces to laminae
Post Elements of Neural Arch
Spinous and Transverse Processes (SP, TP)
- sites for muscle attachments
-spinous process resists compression-transmits forces to laminae
Spondylolysis/Spondylolisthesis
- fracture/fracture w displacement
- fracture to pars interarticularis
- Most frequently at L5-S1
- Increased stress on supporting ligaments and joints
- possible compression of the spinal cord
Intervertebral Discs
- increase in size caudally
- Function: increase available motion and transmit
Intervertebral Discs Innervation
- outer 1/3-1/2 of annulus fibrosis
- Sinuvertebral N.: Surrounding connective tissue and ligaments
Intervertebral Discs Nutrition
- no major arterial branches: metaphyseal capillaries @ endplates
diffusion
Interbody Joint (Cartilaginous)
-sliding
-distraction
-compression
-tilting
Amount of movement varies by region…
-structure (disc, vertebral body, orientation of the ZAJ), ligamentous support(s)
Anterior Longitudinal Ligament (ALL)
-resists extension
-Anterior surface of vertebral bodies from C2-sacrum
-fibers blend with annulus fibrosus
-thickest in lordotic regions
-tensile strength greatest in lumbar (2x PLL)
-May become slackened with degenerative disc disease
Anterior Atlantooccipital & Atlantoaxial membranes
extension of ALL from C2-occiput
Posterior longitudinal ligament (PLL)
-resists flexion
-posterior surface of vertebral bodies from C2-Sacrum
-fibers blend with annulus fibrosus
Ligamentum Flavum
-resists flexion
-posterior surface of the spinal canal
-lamina to lamina from C2-Sacrum
-under constant tension even in neutral
Interspinous ligament
-resists flexion
-connects SP of adjacent vertebra
Supraspinous ligament
-resists flexion
-Cord like, connects tips of SP
Intertransverse Ligament
-resists lateral flexion
-pass between TP
-provide stretch/compression during lateral flexion
Alar ligaments
-resists rotation
- Atlas (C0-C2)
- limit ipsilateral lateral flexion and contralateral rotation
Facet/ZAJ Capsules
-resists forward flexion and rotation
-strongest at transition zones
-Vulnerable in extreme flexion (esp. lumbar)
Coupling
consistent association of one motion about an axis with another motion around a different axis
Pure lateral flexion or pure rotation is rare T or F?
False
only place this is true for the cervical/neck region
Coupling is dependent on…
-spinal posture and curves
-orientation of facets
-fluidity, elasticity, and thickness of intervertebral discs
-extensibility of muscles, ligaments, and capsules
Amount of motion available depends on…
size of the discs
Direction of motion is determined by…
orientation of the facets
Flexion
-body ANT tilts
-Inferior Facets SLIDE up
Extension
-body POST tilts
-superior facets SLIDE down
Lateral Flexion
-int foramen opens contralateral side
-rotation accompanies (varies by region)
Axial Compression
-result of gravity, GRF, muscle and ligament pulls
-Discs and vertebral bodies resist most
-cartilaginous end plates will be first to fail
-help from arches and facets
-nucleus pulpous exhibits creep
Torsion
-axial rotation and coupled motion
-resisted by annulus fibers/facet joints
Shear
-translation of disk
-lumbar - resisted by facets
Bending:
Flexion
-anterior compression
-posterior tension
-limited by post outer annulus, facet capsules, post ligaments, mm
Bending:
Extension
-anterior tension
-posterior compression
-limited by anterior outer annulus, facet capsules, anterior ligaments, SP
Upper cervical spine
occiput (C0) + C1 + C2
Lower cervical spine
C2-7
OA joint
“nodding yes”
-occiput has convex condyles
-C1 (atlas) - concave superior facet (internal facet for dens)
FUNCTION: nodding of the head on C1
AA Joint
“shaking head no”
-C1 inferior convex facets
-C2 (axis) superior convex facets
-Dens facet for C1
ROTATION of C1 on C2
Posterior Atlanto-occipital (AO or C0-C1) and Atlanto-axial (AA or C1-C2) ligaments
continuation of ligaments flavum
Anterior atlanto-occipital and atlantoaxial ligaments
continuation of ALL
Tectorial membrane
cont of PLL
Ligamentum Nuchae
resists flexion
Transverse Ligament
Critical in maintaining C1/2 stability
-holds dens in close proximation to anterior C1
-dens will fracture before ligament tears
Alar ligaments
“cruciate ligaments”
-dens to occipital condyles
-limits axial rotation of head; tightens both
-side bend to the RIGHT causes contralateral occipital fibers to become tight and ipsilateral C1 fibers to become taught (based on ipsilateral movement of C1)
-rotation to R causes C2 spinous process to move L
