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Biomech Ex2
| Question | Answer |
|---|---|
| What does the neural arch consist of? | 2 pedicles, 2 laminae, 7 processes, pars inarticularis |
| What is the site of Spondylolistesis? | pars inarticularis |
| How are the cervical facets oriented? | up ot of the transverse plane 45* |
| How are the thoracic facets oriented? | up out of the transverse plane 60* and internally rotated out of the coronal plane 20* |
| How are the lumbar facets oriented? | up out of the transverse plane 90* and externally rotated out of the coronal plane 45* |
| What is the compressive strength of cortical bone? | 10% |
| What other structures increase the compressive strength of cortical bone? | vertical and horizontal trabeculae |
| At what age does compressive strength decrease? | sharply after age 40 and gradually after age 60 |
| A 25% decrease in bone mass = ? | 50% decrease in strength |
| Where doe end plate fractures occur in non-degenerated discs? degenerated? | central; peripheral |
| What is the strength after a compression fracture? | strenghth is equal to or stronger |
| What did Cox conclude about facet syndrome? | most common condition seen in chiropractic; 26% of people with LBP have facet syndrome either alone or with other findings |
| How much compression force do facet joints carry? torsional force? | 3-33%; 45% |
| How much compressive force do degenerated discs carry on facets? | 47-70% |
| McNab's lines tell us the more _______ the lines intersect the more severe facet syndrome. | anterior |
| What is Facet Imbrication and can this cause nerve root compression? | superior facet rises into IVF; No |
| T/F McNab's lines can be used to determine if a patient has facet syndrome. | False |
| Where were the pain patterns when facet joints were irritated? | referral patterns in buttocks, thighs, legs |
| What do Van Akkerveeken's lines tell us? | the stability of facet syndrome |
| What determines if facet syndrome is unstable? What is the prognosis? | 3mm or greater difference betweem lines from intersection point to posterior margin of body yields instability and poor prognosis |
| When would an 839.X subluxation code be used? | when the dislocation (less than luxation) can be seen |
| What are the functions of spinal muscles? | increase stiffness of spine, provide stability of trunk, produce physiologic movement, protect the spine during trauma and post injury phase |
| isotonic force | contraction of the muscle in which there is no change in the force the muscles produces but length changes |
| isometric force | contraction of a muscle in which there is no change in the length of the muscle but force changes |
| What does the active property of the force curve tell us? | maximum force at 120-130 % of resting length with veyr little force at 50% |
| What does the force curve tell us about passive physical properties? | no force until 100% of its length |
| Would a ligament be active or passive? | passive |
| What does the stiffness curve look like for active? passive? | increases rapidly then saturates; linear |
| How do the muscles function in standing posture? | back muscle activity is generally low, longissimus and rotatores are continually active, slight activity of abdominal and psoas |
| What is the difference in muscle activity for standing and sitting? | thoracic miscle activity increases in sitting |
| What movements increase muscle activity when weights are in your hands? | as load moves anterior, flexing the spine, lateral flexion on contralateral side |
| When are muscles involved in lumbar intersegmental flexion? What muscles? | first 60*; Glut. Max, Glut. Med, and Hamstrings, Erector spinae and other superficial back muscles |
| What is muscle activity at full flexion? | muscle activity ceases excpet iliocostalis |
| When are back muscles active in extension? | only at the beginning and end with increasing activity in abdominal muscles |
| What is muscle activity in lateral bending? | back muscle activity increased on both sides with higher ipsilaterally |
| What is the difference in lateral bending muscle activity with weights in hands and without? Why? | with weights, muscle activity increases on the contralateral side due to gravity; without weights muscle activity higher on the ipsilateral side |
| Why is the load on a disc much greater than the weight of the body above the disc? | center of gravity is anterior to the spine so muscles are pulling inferiorly on posterior spine to maintain balance |
| What are the vscoelastic properties of the spinal cord? | very prominent large histeresis |
| How much strain does the cord contain? What occurs after this point? | can stretch 10% of its length than becomes stiff resistance |
| What occurs in flexion/extension of the spinal canal? | lengthens in flexion and shortens in extension |
| What is the length of the nerve root at L1? S1? Why? | L1= 60mm S1=170mm b/c the spinal cord stops at L1/L2 so nerves below this point need to travel further |
| What is the difference between the protective covering of nerve roots and peripheral nerve? | dural sleeve and CSF cover nerve roots, only epineural connective tissue covers peripheral nerves |
| Where does nerve root entrapment occur in degenerative discs? | posterior to disc and lateral canal due to hypertrophy of facets and Ligamentum Flavum |
| How often does failure strain in nerve roots occur? | approximately 18% |
| What pressure is required to cause physiologic changes in nerve roots? What are these changes? | 30-50mm causes changes in blood flow, vascular permeability, axonal transport |
| What pressure in Pedowitz study could still maintain nerve function? | 50mm Hg after 4 hours had physiologic changes but funtion still maintained |
| What occurred at 100mm Hg for 2 hours? | motor reduced 57% and fully restored in 40 minutes; sensory reduced 74% and never fully restored |
| What happened at 200mm Hg? | motor and sensory reduced 100% and after 4 hours only minimal recovery of motor |
| What is the x,y coordinate plane? | frontal |
| What is the y,z coordinate plane? | sagittal |
| What is the x,z coordinate plane? | transverse |
| What is translation? positive? negative? how is it measured? | direction of straight arrows; away from center; towards center; in meters |
| What is rotation? positive? negative? how is it measured? | direction of curved arrows; clockwise; counterclockwise; in degrees |
| What is a functional spinal unit? | two adjacent vertebrae and their intervening soft tissue |
| How is motion of FSU described? | relative to the subjacent vertebrae |
| motion of rigid body in a straight line in the body always remains parallel to itself | translation |
| motion of a rigid body in which a certain straight line of the body or its rigid extension remains motionless | rotation |
| Instantaneous Axis of Rotation | when a rigid body moves in a plane, at every instant there is a point in the body that does not move; axis perpendicular to plane |
| Helical Axis of Motion | defines three-dimensional motion of a rigid body from one position to another |
| T/F HAM and IAR are analogous for plane motion. | True |
| How many degrees of freedom does a vertebrae have? | 3 different axis each woth rotation = six |
| range of motion | displacement from one extreme to the other of the physiologic range of translation or rotation for each of degree of freedom |
| coupling | the phenomenom of consisten association of one motion about an axis with another motion about a second axis when they are attached |
| pattern of motion | configuration of a path that the geometric center of a body describes as it moves through its range of motion |
| What are considered abnormal patterns of motion | changes in coupling or IAR |
| paradoxical motion | occurs when there are typical flexion patterns at a FSU when the overall motion is extension or vice versa |
| T/F Paradoxical motion can only occur in one type of plane. | False |
| What is the difference between active and passive ROM? | active is normal motion, passive is forced motion into the end of the elastic zone |
| What is the point of origin for the orthogonal coordinate system? | between the sacral cornu |
Created by:
jtnguyen
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