Basic Biomechanics Flashcards
Study of the movement of one articular surface on another without regard to the movement of the bone or the forces producing the movement
Arthrokinematics
In the periphery, movement is named after the direction of motion of the _______ bone
distal
In the spine, the movement is named by motion of the _______ bone
superior
Study of the forces that produce a movement at a joint – traction, distraction, shear
Arthrokinetics
Study of the motion of objects
Kinematics
Study and measurement of motion of a bone in space
Study of movement of a bone around it’s mechanical axis without consideration to the motion occurring at the joint surface or the forces producing the movement
Osteokinematics
Osteokinematics consists of:
Osteokinematic rotation (spin and swing) Translation
- The number of planes through which a bone can be voluntarily moved actively
- There are potentially three dimensions through which a bone can be moved about a joint
Degrees of motion
- A line of reference for osteokinematic motion
- A line passing through the bone perpendicular to the joint surface
Mechanical Axis
- Point where all net forces on the bone are zero
- Bone moves around this point
- Perpendicular to the plane of motion
Axis of movement
Tipping of the concave surface that occurs at the end of motion
Always occurs in the same direction as the glide (slide)
Rock
A rotary movement of one bone rolling on another
Tipping of the convex surface that occurs at the end of motion
Always occurs in the opposite direction to the glide (slide)
Roll
One bone spinning on another
Produced by a pure twisting action
Rarely occurs alone in joints but in combination with rolling and sliding
Spin
- The non-linear motion that occurs either at the joint surface (arthrokinematic spin) or around the mechanical axis of the bone (osteokinematic spin)
Motion of a bone that is produced by a sliding action within a joint
Swing
- The linear motion that either occurs at the joint surface (arthrokinematic swing) or in the plane of the mechanical axis of the bone (osteokinematic swing)
Shortest distance between two points
Swing with no accompanying spin
Bone moves in one plane and in joints that have at least two degrees of freedom Ex. Abduction/adduction and external/internal rotation of the humerus and femur
Swing can occur without the bones taking a curved path
Is functionally abnormal and the exception rather than the rule
Pure (Cardinal) Swing
Is accompanied by spin (conjunct rotation)
Composite or impure arthrokinematic or osteokinematic swing that describes an arc
The bone does not stay in one place
Movement of a point on the mechanical axis from A to B follows a line other than the shortest one (arc)
Ex. flexion and extension at index MCP joint can rotate medially or laterally in mid-ranges; The rotation is undone at extreme ranges
Impure (Arcuate) Swing
All particles in the body at a given time have the same direction of motion relative to a fixed point
There is no center of rotation as the bone moves along a plane instead of through it
Translation
The number of independent axes that a bone can move around
Axes are perpendicular to each other
Degrees of Freedom
In joints with one degree of freedom, movement of the bone is limited to motion about a _____ axis and movement of a bone is produced by a ______ action within a joint
single
sliding
Two degrees of freedom either has a _____ and ______ or two distinct ______
The axes must be ______ to each other Ex. MCP joints, knee
spin and swing or two distinct swings
perpendicular to each other
Three degrees of freedom has a ______ and two distinct _____
Swings must be _______ Ex. Shoulder, hip
spin and two distinct swings
must be cardinal
Adjunct rotation is rotation which accompanies a _______
Can also be performed independently about its own ______
Can be voluntarily _____ or ______
Is a separate _________
May only occur with a joint with more than _______ Ex. specific rotator muscles around the hip and shoulder
swing axis done or undone degree of freedom 1 degree of freedom
A pattern of limitation of motion for a given joint due to inflammation is referred to as a
capsular pattern
Movement composed of a spin that is combined with a conjunct rotation
Composite movement
Composite movement is important in achieving _____ packing of joints
close
Composite movement must have a component of _______
rotation
Composite movement occurs during ____________
most functional movements
Rotation of bone and associated structures that occurs in series in the same direction as that of an adjacent bone
Congruent rotation
In congruent rotation, rotation does not need to be at the same _____
rate
Congruent rotation is a mechanism to prevent _______
torsion
Movement occurring as a result of the shape of the joint surfaces and effect of the ligaments rather than muscular effort
Conjunct rotation
In conjunct rotation, as the ligament tightens it brings the two joint surfaces ______ together
closer together (towards closed pack position)
Conjunct rotation must occur in joints with _______
one degree of freedom
Conjunct rotation is a rotation (spin) which must accompany an _______ swing
impure
Conjunct rotation is characteristic of movements at both ______ joints and the majority of _______ joints Ex. knee extension with lateral rotation
sellar joints and ovoid joints
Consequential movement
Conjunct rotation occurring as a result of a succession of movements
Movement that consistently occurs with another that is not a result of voluntary effort
Coupled movement
Every diadochal movement contains a _______ (_______) movement
consequential (conjunct)
A closed diadochal movement brings the bone _____ from then back to its original position but not necessarily back to its original _______
away
posture
An open diadochal movement does not return the bone to its ______
original position
Diadochal movement occurs during the
2nd swing
Diadochal movement can be undone by performing ________ rotation in the opposite sense during the second swing
adjunct
The most common movement of a bone that brings it towards, and away from, the close pack position of the joint
Habitual movements
Habitual movements are always _______ swings (swing and spin)
arcuate swings
In habitual movements, the swing element ______ the joint structures as it comes toward the close packed position
tightens
In habitual movements, the spin element tautens these elements by producing a ___________ to the structure
spiral twist
Rotation of bone and associated structures that does not occur in series in the same direction as that of an adjacent bone
Incongruent rotation
Incongruent rotation goes against the _________ pattern of movement
habitual
Fractures of long bones are susceptible to _________ rotations
Ex. If the radius fractures below the level of the supinator muscle, the upper fragment is pulled into supination while the lower fragment is pulled into pronation by pronator quadratus
incongruent
Pattern of motion described by the total range of motion undergone during all swings of the mechanical axis of the bone
Ovoid of motion
Syndesmosis
Has an interosseus ligament Ex. inferior tibiofibular ligament
Fibrous Joints
Syncondrosis
Has an articular disc
Symphysis: fibrocartilage
Synotosis: has bony structures
Cartilaginous Joints
Articular surface predominantly hyaline cartilage, sometimes fibrocartilage
Consists of fibrous capsule, synovial membrane, synovial fluid
Synovial Joints
One pair of articulating surfaces
Most common: One surface convex, one surface concave Ex. hip joints, glenohumeral joint
Simple Synovial Joint
More than one articulating pair in a single capsule
Neither will articulate with the surface which belongs to the other
Ex. Radio-carpal joint, ulno-menisco-carpal joint
Compound Synovial Joints
Has an articular disc Ex. sternoclavicular joint, TMJ
Complex Synovial Joints
Concave or convex in all planes
Degree of curvature will vary from point to point
Egg shaped rather than spherical
Ovoid
Shape is spherical
Allows 3 degrees of freedom
Ex. Glenohumeral joint, Hip Joint
Unmodified Ovoid
Degree of curvature is more marked in one plane than the other
Allows 2 degrees of freedom
Ex. MCP, radiocarpal joints
Modified Ovoid
Saddle shape
Predominantly concave in one plane and convex at right angles to this
Tends to be stable and efficient – requires fewer ligaments as the surface is more congruent
Sellar
Joint surfaces are purely concave in one plane and purely convex in the other
Joint surfaces are perpendicular to each other
Allows 2 degrees of freedom – Ex. 1st CMC joint
Unmodified Sellar
The joint surfaces have both a concave and a convex portion in the same plane
Joint surfaces are not perpendicular to each other
Allows 1 degree of freedom – Ex. calcaneocuboid joint
Modified Sellar
Movements occurring in joints
Spin
Slide
Roll
Simultaneous sliding and rolling movements of articular surfaces increase the ____________ at a joint and allows maximal ROM with minimal articular surface area
effective range of motion
Spin is independent
Slide occurs in the same direction as the bone is moving
Roll always accompanies slide except at the beginning and end of movement
Slide is the most important movement
Ex. MCP joint
Concave Ovoid Surface
Spin is independent
Convex surface rolls along the concave surface
Rolls in the same direction as the bone is moving
Slide occurs in accompaniment with the roll
Occurs in the opposite direction to the moving bone in order to increase movement with smaller joint surfaces
Convex Ovoid Surface
Movement within a joint and surrounding soft tissues that is requires for normal ROM but is not performed voluntarily
Is reproduced passively
Most amount of movement is available from the resting position
Accessory movements
When mobilizing a concave on convex surface, the glide is in the _____ direction as the desired movement
same
When mobilizing a convex on a concave surface the glide is in the _______ direction to the desired movement
opposite
Articular surfaces are maximally congruent
The capsule and most of the ligaments are taut
The joint surfaces cannot be separated
Close pack position
Bone fracture is more likely in this position
Close pack position
Combination of swing and spin “screw home” the joints Ex. the knee
Most stable joint position
Position used to test ligament stability
close pack position
Biomechanically efficient position - inability to achieve closed pack position will result in muscle overuse and potential proximal/distal adaptations
Close pack position
The close pack position is important for joint lubrication known as ______
weeping
Can’t mobilize or manipulate in the position
Close pack position
Can use to lock joint above or below to obtain specificity
Close pack position
Should not rest or splint in this position
Close pack position
Any position of the joint that is not close pack
Ligaments and capsule are slack and articular surfaces are not congruent
Loose pack position
Position where joint distraction is available
Easy to mobilize in this position
Loose pack position
Resting position for inflamed joints
Splinting and casting position
Loose pack position
Most distraction of joint surfaces is available
Greatest potential joint space
Rest position
Can mobilize in this position
Use as a resting position for inflamed joints
Position for splinting and casting
Loose pack position
Rest position
