Spinal Biomechanics Flashcards
What is the definition of a plane and what are the three planes of space?
a flat surface determined by the position of three points in space.
sagittal, frontal, transverse
What motions occur in the sagittal plane? What axis (X, Y or Z) is this plane in?
flexion and extension
The X-axis
What motions occur in the frontal (coronal) plane? What axis (X, Y or Z) is this plane in?
right lateral and left lateral flexion
Z-axis
What motions occur in the transverse (axial) plane?What axis (X, Y or Z) is this plane in?
rotation
Y axis
What is the definition of an axis?
a line around which rotary movement takes place or along which translation occurs
What are degrees of freedom?
the number of ways in which a body can move
How many degress of freedom are seen in spinal segments?
6
3 translations, 3 rotations
What is the instantaneous axis of rotation?
a point in the body, or some hypothetical extension of it that does not move when the body moves in a plane
What is a motion segment? What is it comprised of in the spine?
the functional unit/ smallest spinal segment exhibiting biomechanic characteristics of the rest of the spine.
=two adjacent vertebrae, their interconnecting disc, joint, capsule and ligaments
What is coupled motion?
two motions occurring at the same time around two different axes. one motion cannot be produced without the other
What is a loose-packed joint position and what is this position for the spine?
position at which the joint capsule and ligaments are most relaxed and maximum joint play is possible. articulating surfaces are maximally separated.
eg. Spine: halfway between flexion and extension
What is a closed-packed position?
capsule and ligaments maximally tightened, no joint play, maximum contact between articular surfaces.
eg: Spinal extension at the facet joint (other examples slide 237)
How many vertebra do we have in total? how many are in each segment of the spine?
33 vertebrae 7 cervical 12 thoracic (kyphosis) 5 lumbar (lordosis) 5 sacral 5 coccygeal
Which area of the spine has the greatest flexion/extension ROM?
lower cervical (second best is lower lumbar)
Which area of the spine has the greatest axial rotation ROM?
upper cervical
What direction do the condyles of the occiput face? Are they convex or concave? What do they articulate with?
face laterally and inferiorly
convex rockers
articulate with superior articular facet of C1
What direction do the facets of C1 face? Are they convex or concave? What do they articulate with?
face medially and superiorly
concave surface
articulate with the occipital condyles
What is occuring at the occiput during flexion and extension of the C0-C1 joint? What degree of flexion/extension occurs?
flexion: occiput glides posteriorly (10 deg)
extension: occiput rolls anteriorly (25 deg)
*note: the greatest range of motion occurs at the C0-C1 joint
During lateral flexion of the C0-C2 joint, the occiput glides on the (opposite/same) side. What degree of lateral flexion occurs?
opposite. 5 deg
During C0-C1 rotation, the occiput glides (ant./post. eriorly) on the side of rotation and (ant./post.) on the side opposite of rotation. What limits this motion and what is the degree of ROM?
posteriorly on the side of rotation, anteriorly on the side opposite of rotation.
The alar ligament limits this ROM to 5 deg on each side
How many facet joints are at the C1-C2 joint?
3
2 facet joints and the atlas-odontoid joint
What kind of joint is the atlas-odontoid joint?
synovial
What ligaments comprise the odontoid joint? (4)
occipital-odontoid ligament, atlas-odontoid ligament, alar ligament, transverse ligament
In flexion, the C1 articular surfaces glide (ant./post.).
In extension, the C1 articular surfaces glide (ant.post.)
in flexion, C1 surfaces glide posteriorly
in extension, the C2 surfaces glide anteriorly
In lateral flexion of the C1-C2 joint, the articular surfaces of C1 glide on the C2 articular surfaces (toward/away from) the side of lateral flexion? What is the ROM deg?
in lateral flexion, C1 glides toward the side of flexion, with 5 deg of ROM.
Rotation of which joint accounts for approximately half of cervical rotation? The first ______ degrees of rotation occur exclusively at this joint.
the C1-C2 rotation- the first 25 degrees of cervical rotation occur here.
During C1-C2 rotation, C1 surface glides ______ on the side of rotation and _____ on the side opposite rotation. (anterior/posterior)
C1 glides posterior on the side of rotation and anterior on the side opposite rotation.
C2 flexion and extension is primarily what type of motion?
translation
When c2 is compressed anteriorly and distracted posteriorly, with facets gliding apart and joint gapping, the neck is in what type of motion?
flexion (also, same occurs in C3-C7)
When c2 is distracted anteriorly and compressed posteriorly, with approximated facets and compression of inferior margins, the neck is in what type of motion?
extension (also, same occurs in C3-C7)
What are two structural differences between C1/C2 vertebrae and C3-C7 vertebrae?
wide transverse body size
transverse foramen for the vertebral arteries
articular facets of the C3-C7 vertebrae are at a ______ deg angle with the transverse plane and ______(parallel/perpendicular) to the frontal/coronal plane.
45 deg angle to the transverse plane
parallel to the frontal plane
The joints of Luschka form at age ____ and complete forming by age ______. What is another name for the joints of Luschka?
6-9, completing at age 18
uncinate process
What is the purpose of the Joint of Luschka? What motions do they couple?
limits lateral flexion,
couples lateral flexion with rotation
The cervical curve is ______(lordotic/kyphotic) at ____ degrees. and it is a (secondary/primary) curve?
lordotic at 20-50 degrees
a secondary curve
The cervical disc height to body ratio is:_______, allowing for:___________
2:5, allowing for greater range of motion
cervical discs are higher _____-(anteriorly/posteriorly), causing the nucleus pulposus to be slightly ________ (anterior/posterior) to center.
cervical discs are higher anteriorly (contributing to lordosis),
thus the nucleus pulposus is slightly posterior
The average ROM in flexion/extension in the lower cervicals is:
15 degrees (highest is mid cervicals, 20 degrees; lowest is C2-3/ C7-T1 with 10 degrees)
flexion/extension at the lower cervicals is a combination of what two types of movement?
segmental tipping (sagittal rotation) and gliding (sagittal translation)
The average lateral flexion ROM at the cervical disc is _____ degrees.
7-8 degrees
lateral flexion of the cervical spine is coupled with what motion?
ipsilateral axial rotation
lateral flexion and coupled rotation of the cervical spine decreases as one moves (caudally/rostrally)?
caudally
During lateral flexion of the lower cervical spine, disc wedging and approximation occur ______ and distraction is present on the _____. (which side of lateral flexion?)
wedging and approximation occur on the same side of lateral flexion
distraction occurs on the opposite side of lateral flexion
facets glide down and medially ipsilaterally and glide up and laterally contralaterally in the lower cervical spine. what motion is occuring?
lateral flexion
average ROM for lower cervical rotation is:
5 degrees
axial rotation of the lower cervical spine is coupled with what motion?
ipsilateral lateral flexion