IVD (Quiz 1/Test 1) Flashcards
How many IVDs ligaments are there? Where are they found? How are IVDs named?
-23 pad-like ligaments
-found from C2/C3-L4/S1
-named for both vertebrae or vertebra above
How many regions are there within IVDs?
2- annulus fibrosus and nucleus pulposus
What is the annulus fibrosis?
quiz/test q
-outer portion of an IVD
-12-20 concentric layers
-thick, tough strong fibrous laminae
-tightly fused to superior/inferior epiphyseal rims
-fused to anterior/posterior longitudinal ligaments
-has multiple fiber orientations
-accommodates torque, tilt, shear
-CANNOT accommodate axial compression
What is the nucleus pulposus?
-pulpy center of IVD
-semi-gelatinous, yellow mass
-has protein (mucopolysaccharide) matrix, chondrocytes, water
-notochord remnant embryologically
-main shock absorber of IVD
-highly hydrophilic (88% water)
-accommodates axial load
What gives the disc its elasticity?
preloaded state
Compression forces on the IVD are seen more in the _______ discs. It bears nearly half the body weight
L5/S1
Which IVD is most susceptible to damage with violent overload?
L5
Which IVD is the thickest?
lumbar (9mm)
Which IVD is the thinnest?
cervical (3mm)
What happens to IVDs when the spinal column is elongated?
-disc becomes spherical
-the increase in disc height reduces internal pressure, (treatment for disc prolapse is spinal traction in this case)
What happens to IVDs when the spinal column has axial compression?
-increased internal pressure from the nucleus is transmitted to the innermost fivers of the annulus
-the vertical force becomes lateral force tightening up the annular fibers
What happens to IVDs when the spinal column is in extension?
the vertebra above tilts posterior, driving the nucleus anteriorly, increasing the tension and thus “balancing” the vertebrae
What happens to IVDs when the spinal column is in flexion?
upper vertebra tilts anteriorly, driving the nucleus posteriorly, increasing the tension of the annulus and restores the upper vertebra to initial position
What happens to IVDs when the spinal column is in lateral flexion?
upper vertebra tilts to the same side as the flexion, driving the nucleus in the opposite direction
couple nucleus-annulus motion leads to self-stabilization
What happens to IVDs when the spinal column is in axial rotation?
MOST VULNERABLE POSITION
-oblique fibers running counter to the direction of movement are stretched while the intermediate fibers with opposite orientation are relaxed
-the strongly compresses nucleus’s internal pressure rises in proportion to the angle of rotation
-flexion and rotation lead to tear the annulus and drive the nucleus posteriorly through the annulus fibers
-whatever force is applied to the disc, it will ALWAYS INCREASE the internal pressure of the disc and stretched the fibers of the annulus
-the couple stretch of the annulus balance the system
