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52 Cards in this Set
- Front
- Back
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The spinal column is divided into five regions. List the name of each, how many segments in each, and the direction of curve in each IN NEUTRAL POSITION (use medical terminology)
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33 total vertebral bony segments
Cervical - 7 segments - Lordosis- convex anteriorly and concave posteriorly Thoracic - 12 segments - Kyphosis- concave anteriorly and convex posteriorly Lumbar - 5 segments - Lordosis- convex anteriorly and concave posteriorly Sacrum - 5 segments - Kyphosis- concave anteriorly and convex posteriorly Coccyx - 4 segments (Usually sacral and coccygeal vertebrae are fused in adulthood) - Sacral segments are fused, coccygeal segments are fused, but there is an inconsistent sacral-coccygeal joint |
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What is the function of the curves in the spinal column?
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This curvature functions to disperse loading and shock
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The plural of vertebra is
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vertebrae
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An individual vertebral segment is sometimes conceptually divided into anterior elements and posterior elements. What structures are included in each?
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a. Anterior elements: large vertebral body
b. Posterior elements: transverse processes, spinous processes, laminae, and articular processes c. Pedicle |
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Another name for the posterior elements is the:
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vertebral or neural arch
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The lamina is between _________________ and each ____________________.
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the base of the spinous process,
transverse process |
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Name the two types of bone in vertebra and describe briefly the structural implications of each:
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Cortical Bone/ Compact Bone
- Stronger but heavier Trabecular Bone/ Spongy Bone/ Cancellous Bone - Withstands compression (not as strong as cortical bone) - Lightweight—less energy expenditure for movement - Living tissue/fresh cadaver—vertebral bodies are a bit squishy |
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What is the clinical significance of the type of bone that makes up most of the vertebral body?
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Lightweight and a bit "squishy"
It hypertrophies due to increased loading Osteoporosis always affects this type of bone |
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Wolff’s Law can be paraphrased as:
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bone follows the stresses placed on it
“Bone is laid down in areas of high stress and reabsorbed in areas of low stress” |
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What is the detrimental clinical significance of Wolff’s Law?
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Formation of bone spurs
Loss of bone due to chronic unloading (can lead to compression fracture) |
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What is the beneficial clinical signficance of Wolff’s Law?
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More bone is laid down as stresses are applied
We can add to bone density with appropriate loading |
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What is the shape of the lumbar vertebral body?
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Massive and Wide
L5 is slightly wedge shaped So it can articulate with the sacrum and maintain lordosis |
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What is the shape of the lumbar vertebral canal?
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Triangular
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What is the main function of the vertebral body? Does it do this job alone?
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To support the entire superimposed weight of the head, trunk and arms
- Load bearing but they are not designed to absorb 100% (facets absorb small load) - The normal curves of the spine help minimize compressive load |
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Locate the pars interarticularis on a model of a lumbar vertebral segment.
a. Why is it called “interarticularis”? b. Located between _________________ and _________________ c. In standing or forward trunk flexion, what is the function of the pars interarticularis (it resists what?) |
a. it is in between the articular processes
b. the superior and inferior articular processes of the facet joint and between the pedicle and lamina c. resists shearing forces but they also decreases the load on the apophyseal joint - The pars is flexible in a living person—could act as a shock absorber and decrease impact loading on the facets |
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What kind of movement(s) is/are most likely to cause structural failure in the pars interarticularis?
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Repetitive loading with flexion and extension p. 351
- The fact that the pars bends is part of what makes it a problem. After enough bends it weakens and may fail. "coat-hanger effect" |
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What level of the lumbar spine is most likely to undergo failure of the pars interarticularis?
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L5-S1
because this segments has the most flex/ext, which are movements that damage the pars |
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Unilateral failure of the pars interarticularis is called
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spondylolysis
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If the pars interarticularis fails bilaterally, what is likely to occur between the two adjacent segments?
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Anterior slippage of the disk, narrowing the spinal canal
If this occurs, it is called spondylolesthesis |
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What bony structure primarily limits trunk extension?
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Spinous process
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at the spinous and transverse processes on a model of the vertebral segment. Why do you think they are shaped like they are?
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Transverse process of lumbar spine are projected laterally L1-4 are thin and tapered. The spinous processes are broad and rectangular projecting horizontally from the junction of each lamina. I believe they are shaped this way because the lumbar spine supports the most weight of the body (head, trunk, and arms). Muscle attachment, limits movement (especially extension)
Bony attachments for muscles. sticks out from the neural arch for a greater lever arm and mechanical advantage. It will take less force to do something. Postural muscles are firing all the time so you don’t want them to work really hard because they will fatigue. |
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The intervertebral foramen (IVF) is created by what bony structures?
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Facets, disc, pedicles, body
Lower 1/3 of vertebral body Ligamentum flavum Pars interarticularis Upper 1/3 of vertebral body |
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What passes through the IVF?
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Dorsal root ganglion, segmental arteries and veins
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Facet joints are also known as
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zygapophyseal joints or apophyseal joints.
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Facets are what type of joint?
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Facet joints are plane (synovial) joints and lined with articular cartilage and enclosed by a synovial lined, vastly innervated capsule.
Clinical significance: pain, capsule limits flexion. Synovial joint needs movement to stay lubricated. Arthritis, synovitis, osteophyte |
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What spine disorder primarily consists of degeneration of the facet joints?
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Osteoarthritis - Facet joint degeneration
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What is the other main function of the facet joints? (in addition to guiding movement)
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The orientation of the plane of the facet surfaces within each joint influences the kinematics at each region—more horizontal favor axial rotation, more vertical block axial rotation
- L1-L4 (upper L)- mostly vertical (in sagittal plane—divides R/L) –allows flex/ext, but not much rotation (Figure 9-32, Pg. 328) - L5-S1 –changes to more oblique between frontal and sagittal place—limits LF and rotation |
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The facet joint capsules aid the facets in fulfilling the function named in the previous question by acting as ...
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Ligaments
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Look at a model in which lumbar vertebral segments are articulated and make sure the segment is right-side up. Which of the facets is the superior facet?
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They form the bottom of each facet joint
One facet joint is made of the Inferior facet (above) of the higher vertebra and the Superior facet (below) of the lower vertebra |
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In the static upright anatomical position, what other function do the facet joints fulfill?
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They block anterior translation of one vertebrae on another. Functionally this is important because excessive anterior translation significantly compromises the volume of the vertebral canal – the space occupied by the spinal cord and or passing spinal nerve roots. In general, horizontal facet surfaces favor axial rotation and vertical facet surfaces block axial rotation. Neuman 327-328
The sturdy articular facets of the L5-S1 apophyseal joints provide bony stabilization to the L5-S1 junction. Neuman 349 L5-S1 is more load bearing because it is more oblique |
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Heterophile-negative mononucleosis in children and adults
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CMV - Herpesviridae 5
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What is the clinical significance for a patient that must stand for prolonged periods of time?
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During standing, lumbar lordosis can be increased by anterior tilting of the pelvis which will also cause an anterior shearing at the L5-S1 junction. Due to abdominal fatigue. Prolonged standing may increase LBP for those with facet dysfunction or radicular pain (because the size of the IVF will be decreased).
Spondy pts—may also be irritated by prolonged standing |
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What is the facet orientation in L1-L4?
What is the functional significance of this facet orientation? |
Nearly vertical, with a moderate-to-strong sagittal plane bias. This orientation favors sagittal plane motion at the expense of rotation in the horizontal plane. Neuman page 346
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What is the facet orientation in L5-S1?
What is the functional significance of this facet orientation? |
It is oblique—therefore it resists shear more and is more loadbearing
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Decreased disc height causes what change at the facet joints?
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Greater compressive loads at the joints - arthritis
Bone on bone interface blocks rotation in the sagittal and frontal planes – allowing only excessive tipping and translation. |
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Decreased disc height causes what change at the IVF?
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Decreased disc height causes decreased passage for exiting spinal nerve roots -> nerve root impingement, osteophytes
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Describe briefly the structure and function of the vertebral end plate
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Relatively thin cartilaginous caps of connective tissue that cover most of the superior and inferior surfaces of the vertebral bodies. In adults they recede and only occupy about 5% of the height of each intervertebral space. The surface that faces the disk is mainly fibrocartilage that binds directly and formly to to the collagen within the annulus fibrosus. This forms a primary adhesion between consecutive vertebrae. The surface that faces the vertebral body is composed of calcified cartilage and is weakly affixed to the bone.
Barrier between nucleus and vertebral body. Nutrients must pass through it to get to the disc |
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How much of our total lumbar flexion occurs at L5-S1?
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75%
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How much of our total lumbar flexion occurs at L4-L5?
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20%
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The first structure to be damaged by excessive compression is the
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Vertebral end plates
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What is the difference between an intraspongy nuclear herniation and a Schmorl’s node? What is the longer term clinical significance of these problems?
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Intraspongy nuclear herniation is traumatic and causes local pain. Schmorl’s nodes are developmental defects that occur only in adolescents and are not painful.
both flatten the disc space which limit movement |
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How does a disc receive nutrition? What is the effect of movement on this process?
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Diffusion
Movement and normal loading/unloading creates fluid level changes that bring in nutrients and remove waste |
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How does a disc absorb shock (describe the transmission of loading force)
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- Compression force from body weight and muscle contraction raises the hydrostatic pressure in the nucleus pulposus. In turn, the increased pressure elevates the tension in the annulus fibrosus.
- The increased tension in the annulus inhibits radial expansion of the nucleus. The rising nuclear pressure is also exerted upward and downward against the vertebral endplates. - The pressure within the disc is evenly redistributed to several tissues as it is transmitted across the endplates to the adjacent vertebrae. |
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What is the other main function of the disc (in addition to load bearing and shock absorption)?
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Allowing and restricting movements
- Increased disc height=increased movement - The annulus also acts as a ligament to stop movements |
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What is the relationship between disc height and the amount of movement allowed at the interbody joint?
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Intervertebral discs constitute ~25% of the total height of the vertebral column. The greater the relative invertebral space, the greater the ability of one vertebral body to “rock” forward and backward on another. Without any disc space, the nearly flat bone-on-bone interface between two consecutive bodies would block rotation in the sagittal and frontal planes – allowing only excessive tipping or translation. Also, the space created by the disc creates adequate passage for the exiting spinal nerve roots
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What are two main functions of the annulus fibrosis?
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The outermost peripheral layer provides circumferential strength and flexibility to the disc, as well as, a means to bond the annulus to the anterior and posterior longitudinal ligaments and to the adjacent rim of the vertebral bodies and endplates. (Neumann pg. 329) attaching one vertebral body to another
b. Encase and physically entrap the liquid-based central nucleus (Neumann pg. 329) |
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What is the composition of the nucleus pulposus?
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Pulp-like gel
15-20% collagen Protoglycan network (proteins) Small number of chondrocytes and fibrocytes |
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What does hydrophilic mean?
What is the clinical significance of the nucleus being hydrophilic? |
“water-loving”
Hydrophilic is the capacity to retain water within the disc. The low pressure within the disc combined with its hydrophilic nature attracts water into the disc, which enables the nucleus pulposus to exert a relatively large hydrostatic pressure. This high pressure increases keeps the disc from becoming “flattened” and bulging outward when compressed. Allows for nutrients to be brought in and waste to be removed |
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How does age affect the nucleus?
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less hydrophilic
fewer proteins |
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How does age affect the annulus?
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Disruption of fibers may lead to herniation/prolapsed nucleus propulsus
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What is the clinical significance of the previous two changes in middle age? (nucleus / annulus)
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The previous two changes can lead to severe disc dysfunction including prolapse/herniation, sequestration, or extrusion. These physiological changes can lead to nerve impingement causing neurological impairments and/or low back pain for an individual. The lack of water within the disc leads to increased load on the vertebrae and decreased shock absorption.
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What is the effect of upright posture on the nucleus?
What is the clinical significance of this change in the nucleus? |
Anterior pelvic tilt allows a normal amount of lordosis and pushes the nucleus anterior. Gravity working on us all the time causes a compression force on the nucleus and squeezes it out. Over the course of the day there is decreased disc height -> bodies/facets are more approximated -> smaller IVF
More pain / symptoms by the end of the day |
