biomechanics week 4 Flashcards
Arthrokinematics
motion that occurs between articular surfaces of joints
What are the shapes of the bones that make up most joint surfaces?
one convex and the other concave
Convex
curved out, hill
Concave
curved in, cave
why is the convex concave joint structure importaint? 4 reasons
- Increase contact area, 2. increase stability, 3. Increase dissipation of forces, 4. guides motion of bone
What are the 5 movements that occur between joint surfaces?
- Roll, 2. slide, 3. spin, 4. distraction and longitudinal traction, 5. compression
Roll
rotation across a surface/ multiple points along one contact multipul points along other surface
slide
gliding across surface/ single point on one surface contacts multiple points on another
spin
spin in one spot/single point on one surface rotates on single point on another articular surface around a stationary longitudinal mechanical axis
distraction and logitudinal traction
joint surfaces are pulled apart
compression
decrease in the space between two joint surfaces
Example where roll movement takes place?
femoral condyles rolling on tibial plateau
In what direction does roll occur in reguards to direction of movement?
Roll happened to the same direction as movement.
What joint movements often occur with roll? 2
Roll cocurs in combo with sliding and spinning
Example of slide?
carpal bones slide along their facet surfaces
Do concruent or uncongruent surfaces have the most slide?
Sliding happens on more congruent surfaces while spinning happens on uncongruent surfaces
What joints have a spin movement?
humeroradial joint for supination/pronation
Can spin occur by itself during normal joint motion
no, I think it always has another join motion with it.
When would distraction and longitudinal traction be used?
to stretch a joint capsule and mobilize a joint
Longitudinal traction
longitudinal pull along bone
distraction
pull, separtation of joint surfaces
spinal traction
longitudinal pull along axis of spine
compression
decrease in space between two joint surfaces
What is the normal response of a joint to muscle contraction
Compression, decreases the space between joint surfaces
what does compresson do?
adds joint stability
In the convex on concave and concave on convex motion, which one is anchored?
the second half is the shape that is anchored, convex on concave means that the concave side of joint is anchored
Movement of convex on concave joint?
convex joint suface is mobile, it slides in a direction opposite from where it rolls
Movement of concave on convex?
Concave joint surface is mobile, it slides in the same direction as it rolls.
what joint can be concave on convex on concave
the knee, its convex on concave if standing, its concave on convex if foot is swinging freely
Why do we care about the direction and movement and roll?
because when we facilitate joint movement we don?t want to do it in the wrong direction
Physiological movements
movement of bones done voluntarily , osteokinematics
acessory movements
movement necessary for normal joint range of motion but cant be preformed voluntairly.
Example of two acessory movements?
longitudinal traction and detraction
Example of a problem with acessory movements?
tighness in ligament and joint capsule can cause movement restrictions or aberrant joint motion
Joint play
motions that occur within joint but only as a response to an outside force
what determines joint play?
joint capsules laxity determines joint play
How can joint play be demostrated?
demonstrated passively but it cant be performed actively
End feel
way joint play movements are interpreted and measured
Is physiological mobilization osteokinematic or arthrokinematic?
physiological mobilization is osteokinematic
What movements are arthrokinematic?
acessory movements - joint movement
what rule would be followed to restore normal joint play?
follow convex-concave rule to increase pain free joint range of motion
Movements of glenohumeral abduction? Why?
Roll, slide and spin, spin so greater trochanter doesn?t hit chornoid process
Movement of knee extension (think standing up)
convex on concave, movements are roll, slide and spin
Movement of knee flexion (think foot back to kick)
concave on covex, movement is roll slide and spin,
Plane is determined by what?
flat surface determined by 3 points in space.
what planes do we deal with?
saggital - splits us side to side, frontal- splits front to back, transfers- top to bottom
What is plane motion?
motion in which all points of a rigid body move parallel to a fixed plane
What is a saggital plane motion, remember sagital splits us into right and left
Flexion and extension, because when you flex/extend the movement is parallel to the saggital plane.
What is normal frontal/coronal motion?
abduction adduction, because those movenets are parallel to the coronal plane
What is normal motion of tranverse plane?
rotation, turning head, twisting., parallel to tranverse plane
What are the dimential limitions of plane motion?
its two dimentional
What are the dimential limitionas of out of plane motion?
its three dementional, all points of rigid don’t move in single plane, circumvex
axis is what
line around which rotary movement or translation occurs
what are the directions of the x axus
- x-side to side axis, perpendicular to saggital plane
What are the directions of the Y axis?
y axis pointing up through skull, perpendicular to the transverse plane
What are the directions of the z axis
z axis, front to back, perpendicular to the coronal/frontal plane
Other name for z axis?
saggital
Other name for y axis
longitudinal axis
Other name for x axis
coronal/frontal axis
What is ment by degrees of freedom?
number of ways in which body can move
how many degrees of freedom does a spinal segment have
spinal segments have 6 degrees of freedom, 3 translations and 3 rotations,
What is instaneous axis of roation?
idea that when a rigid body moves in a plane, there is a point maybe a hypothetical extention that doesn’t move
what is used to descrive any vertebral motion in a two dementional plane?
instaneous axis of rotation
Is the Instaneous axis of rotation the same for the entire spine?
No, its different for each section, thorasic, lumbar, cervical and different under different loads
what is the functional unit of the spine?
motion segment
What makes up a motion segment?
two adjacent vertebrae and their interconnecting disc, joints, capsule and ligaments
characteristics of a motion segment?
smallest spinal segment (2) exhibiting biomechanical characteristics similar to those of the entire spine with 6 degrees of freedom
what ligament is around articular fascets
capsular ligaments
what is the pedicle joint called?
zygapophyseal joint with a joint space
what is coupled motion?
two motions ocuring at the same time along different axes
what joints have loose packed position?
fascet joints are loose packed half way between flexion and tension
what is the loose packed joint position used for?
traction or joint mobilization
what makes up a lose packed joint position?
1) capsule and ligamens are most relaxed, 2) maximum joint play is possible, 3) articulation surfaces are maximally separated
what is a close packed joint position?
capsule and ligaments are maximally tightened with no joint play and maximal contact between articular surfaces
when would there be close packed joint position of spine?
flexion or extension of spine.
What spinal section is the most movable
cervical can do the most,
what is the least movable section?
probably the thorasic, can barely do anything.
What can the lumbar do best and worst?
Best at flex and extend, not so good at rotation
what cervical part has most rotation?
the first one and skull
does C1 do lateral bending?
nope
What does better flexion and extension?
Lumbar does better flexion while cervical does more extension
what has the best lateral flexion?
cervical can do the most,
what section has best and worst rotation?
lumbar has worst rotation wile cervical and thorasic is almost equal
where do the concyles of the occiput face?
laterally and inferiorly so they can sit in C1 articular facet
Where to the atlas C1 facets face?
medially and superiouly so they fit the condyles of occiput
what does the fascet/condyle joint allow?
rocking
In which direction does the occipit glide?
Occiput glides posteriorly to flex 10 degress
In which direction does occiput roll?
occiput rolls anteriorly to extend. 25 degrees
Where is the greates range of motion?
CO and C1 (atlas)
what is gliding and rolling during occiput C1 flexion?
Occiput rolls on side of flexion and glides on opposite side
what limits CO-C1 rotation?
alar ligament 5 degrees each side.
where does gliding and rolling happen during rotation?
glide posteriorly on side of rotaion and anteriorly on side opposites
what is the atlas axis joint around odointoid process called?
atlas odontoid joint
what type of joint is the atlas odontoid joint?
synovial
what is the ligament that ties odontoid process in?
transverse ligament
