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
During lower cervical rotation: on the side of rotation the inferior facets glide:-________ and ______
on the opposite side of rotation the inferior facets glide:______ and ______
on the side of rotation, they glide down and medially
on the opposite side of rotation, they glide up and laterally
What are two properties of thoracic vertebrae shape?
TPs are thick, strong, long
SP are long and slender
What are two facet joints on thoracic vertebrae that articulate with the ribs?
Costovertebral joint ( rib heads) Costotransverse joints (rib tubercles)
Thoracic articular facets for a ____ degree angle from the transverse to the coronal plane and a _____ degree angle from the coronal towards the Sagittal plane.
60
20
Inferior thoracic facets face _______, _________ and _______-ly
Inferiorly, medially and anteriorly
Superior thoracic facets face ______, ________ and _______-ly
Superiorly, laterally and posteriorly
Which thoracic vertebrae articulate atypically? What type of vertebrae do they act more like?
T1 acts more like C7
T11 and 12 act more like lumbar
The thoracic is a _______ curve, at _____ degrees. Is it a primary or secondary curve? Where is the curves apex?
Kyphotic at 20-50degrees. Primary curve, with apex at T6-7
Flattening of the thoracic curve will cause what three things?
Decreased cervical curve
Cervical curve shifts forward
Increased lumbar curve
What is the thoracic body height: disc ratio? Is the thoracic spine more or less flexible? Where is the nucleus pulposus located?
1:5
Least flexible part of the spine
N. Pulposus is centrally located
What is the degree of flexion in the thoracic spine?
Average 6
Upper thoracic: 4
Middle: 6
Lower thoracic: 12
What two motions are coupled during spinal flexion?
Sagittal rotation and Sagittal translation
What happens to thoracic discs and facets during flexion?
Facets glide apart, disc opens posteriorly
What happens to thoracic facets and discs during extension?
Facet joints and posterior discs approximate
Thoracic lateral flexion is about _____ degrees of ROM. What movement is coupled with thoracic lateral flexion?
6 degrees
Coupled with axial rotation. Ipsilateral in upper Thoracics, but can be to both sides in lower thoracics
How do thoracic discs and facets move during lateral flexion? What is unique to upper thoracic motion?
Discs and facets approximate on the side of flexion, separate on opposite side.
In upper thoracic, discs glide medially on the side of flexion and laterally on opposite side
What is the average ROM degree in upper thoracic rotation?
8-9 degrees
upper thoracic rotation is coupled with:
same side lateral flexion
during thoracic rotation, inferior facets glide______ on the same side of rotation and _____ on the opposite side of rotation.
inferiorly on the same side
superiorly on the opposite side
What is the pump-handle movement of the ribs, and what does this movement do to the A-P diameter of the rib-cage?
rib head rolls downward, elevating the anterior portion of the rib
this increases the A-P diameter of the ribcage
What is the bucket-handle action on the rib-cage and what does this action do to the shape of the rib cage?
ribs elevate on TPs
this increased the transverse diameter of the rib cage
What is the Caliper-action on the rib cage and what does this movement do to the shape of the ribcage?
ribs move apart from each other with inspiration
this increases the lateral diameter of the ribcage
What are four characteristics of lumbar vertebrae (SPs/TP characteristics, etc)?
short, broad, strong pedicles and laminae
thick, broad SPs
long, slender, flattened TPs
Mammillary processes
lumber articular facets are primarily in the _____ plane, but become more _____ and the lumbosacral junction
primarily in the sagittal plane but become more coronal
What is the greatest flexibility in the lumbar spine?
flexion/extension (facet orientation limits rotational flexibility)
The lumbar curve is a ______ (kyphotic/lordotic?) curve at ___-____ degrees. Where is it’s apex, and is it a primary or secondary curve?
lordotic curve at 20-60 degrees.
apex at L3-L4
a secondary curve (in response to standing)
An anterior pelvic tilt ________ (increases/decreases) lordosis. A posterior pelvic tilt ________ (increases/decreases) lordosis.
anterior tilt increases lordosis
posterior tilt decreases lordosis
What is the lumbar disc height:body ratio? Where is the nucleus pulposus? What two things do these characteristics allow the lumbar spine to do?
1:3, with N.pulposus posteriorly.
allows for movement
allows resistance to axial compression forces
What is the process of force transmission through a disc that allows stable weight-bearing?
- compression raises n.pulposus hydrostatic pressure
- ->elevated annular fibrosis pressure
- -> inhibits radial expansion of a. fibrosis
- ->increased upward/downward nuclear pressure
What is a disc bulge? What does it cause?
generalized extension of disc tissues beyond the edges of the vertebral body <3mm (NOT A HERNIATION). May compress neural tissue causing pain and joint dysfunction
What are two types of bulging discs? Which one is found in scoliosis?
symmetrical and asymmetrical (found in scoliosis)
What is a disc herniation?
when n.pulposus ruptures through the a.fibrosis. causing an inflammatory response and compressing neural tissue. may cause radicular and somatic pain
A localized process involving <50% of disc circumference
What is a focal herniation?
A herniation that involves <25% of disc circumference
What is a broad-based herniation?
A herniation that involves between 25-50% of the disc circumference
What two forms may herniated discs take?
protrusion (base of herniation is greater than distance of protrusion) and extrusion (disc material balloons out as if budding off)
What are three types of annular tears? What three things might these cause?
radial, transverse, concentric tears (fissures)
- weaken the disc
- generate pain
- disc material may migrate into tears
lumbar segment combined flexion/extension ROM is;
15 degrees
during lumbar flexion vertebra tilts and slides ______ (ant/post) facets glide ______ (sup/inf?) disc is compressed _______(ant/post?) and stretched _______ (ant/post?)
vertebra tilts and slides anteriorly… facets glide superiorly …disc is compressed anteriorly and stretched posteriorly
during lumbar extension, vertebra tilts and slides ______ (ant/post) facets _______ (approximate/distract), facet capsule, disc and anterior longitudinal ligament are _______ (stretched/relaxed)___________(anteriorly/posteriorly?)
extension …vertebra tilts posteriorly … facets approximate … facet capsule, disc and anterior longitudinal ligament are stretched anteriorly
Lumbar lateral flexion ROM averages about _____ on each side. The lumbosacral joint only has _____ degrees ROM.
6 degrees
3 degrees at lumbosacral jiont
lumbar lateral rotation is coupled with:
opposite side rotation (OPPOSITE OF CERVICAL AND THORACIC)
during lumbar lateral flexion facets glide ______ on the side of flexion and _____ on the opposite side (apart/together)
together on the side of flexion
apart on the opposite side
Lumbar rotation ROM is only ______ degrees. What limits this rotation?
2 degrees, limited by facet joints
Lumbar rotation is coupled with what two motions?
lateral flexion and slight sagittal plane rotation
rotation of L1-L3 is coupled with _____ lateral rotation, whereas rotation of L4-L5 is coupled with _______lateral flexion (same side/opposite side)
L1-L3 rotation opposite side lateral rotation
L4-L5 rotation same side lateral rotation
What bones and features are in the pelvis (3) and What are two joints in the pelvis?
innominate bones, sacrum and the pubic symphisis
lumbosacral joint
sacroiliac joints
The innominate is a fusion of what three bones?
ilium, ischium, pubis
What type of joint is the pubic symphisis? how movable is it?
amphiarthrosis joint (slightly moveable) with a fibrocartilaginous disc
What type of nerves exit the sacral formina?
autonomic parasympathetic
What type of joint is the sacroiliac joint?
part fibrous and part synovial (diarthrosis)
Heavy ligametnous attachments of the sacroiliac joint are on the _______ and ______ surfaces.
(posterior and superior)
What are four characteristics of the articular surface of the sacrum in the sacro-iliac joint?
diarthrosis
L-shaped
hyaline articular cartilage
central concave groove
What ligament in the sacroiliac joint can calcify with age, leading to immobility and pain?
the iliolumbar ligament
What is the “Z” joint?
the L5-S1 zygapophysial joint
Name the 8 ligaments of the posterior pelvis
posterior sacroiliac lig. sacrotuberous lig superficial dorsal sacrococcygeal lig. sacrospinous lig. deep dorsal sacrococcygeal lig. dorsal sacroiliac lig. interosseous sacroiliac lig iliolumbar lig.
inferior displacement of the pelvis is prevented by:
the wedge shape of the pelvis
posterior displacement of the pelvis is prevented by:
sacroiliac ligaments
anterior displacement of the pelvis is prevented by:
sacroiliac ligaments and the pubic symphysis
What is meant by “form closure” of the pelvis?
the anatomy of the SI joints promotes stability
wedge shape, interlocking grooves and S-shaped joint surfaces, eg.
What is meant by force closure of the pelvis?
tension in muscles, ligaments and fascia aids in stabilizing the SI joints.
creates lateral-medial pressure (“X” shaped muscles across the back)
What is the function of pevic dynamics?
as a shock absorber, to absorb and adapt to forces
What is meant by “nutation” of the SI joint?
the sacral base rotates anteriorly on the ilium/ the ilium rotates posteriorly on the sacrum
What is meant by counternutation of the SI joint?
the sacral base rotates posteriorly on the ilium/the ilium rotates anteriorly on the sacrum
What are three things that are caused by moving into nutation?
anterior sacral tilt, posterior iliac rotation, increased lumbar lordotic curve
What are three things that are caused by moving into counternutation?
posterior sacral tilt
anterior iliac rotation
decreased lumbar lordotic curve
What are four ways in which the pubic symphysis can move?
compression, distraction
rotation in sagittal plane with SI joint motion
gliding (translation) in anterior/posterior and superior inferior directions
During hip flexion, the PSIS moves _____ and _____, accompanied by ipsilateral ______ movement of the sacral base.
PSIS moves posteriorly and inferiorly
sacral base moves anteriorly and inferiorly
During hip extenion, the PSIS moves _____ and ________ly, accompanied by ipsilaterl ______ movement of the sacral base.
PSIS moves anteriorly and superiorly
sacral base moves posteriorly and superiorly
An anterior pelvic tilt can be caused by contractions of what three muscles?
rectus femoris, iliopsoas, erector spinae
A posterior pelvic tilt can be caused by contraction of what 4 muscles?
gluteus maximus
hamstrings
rectus abdominus
obliquus externus abdominis
