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Biomech Ex2

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