biomechanics Flashcards
Recognized as the first true biomechanist
• First to study anatomy in the context of mechanics
• Analyzed muscle forces as acting along lines
connecting origins and insertions and studied joint
function
Leonardo da Vinci
• Interested in the strength of bones
• Noted that animals’ with large mass bones increase
in girth
• Theorized adapted to loadbearing
• Suggested that bones are hollow for this affords
maximum strength with minimum weight
Galileo Galilei
Studied walking, running, jumping, and even the piston
action of the heart within a mechanical framework
• Determined
• Position of the center of gravity
• Calculate and measured inspired and expired air
volumes
• Showed that inspiration is muscle-driven and expiration
is due to tissue elasticity
Giovanni Alfonso Borelli
Biomechanics describe the
relationship
between structure and function
Machines function in four ways
Balance multiple forces
2. Enhance force in an attempt to reduce total force
needed to overcome a resistance
3. Enhance range of motion & speed of movement so
that resistance may be moved further or faster than applied force
4. Alter resulting direction of the applied force
3 types of “machines” in producing movement
Levers (most common)
• Torque and length
2. Wheel-axles
• Function essentially as a form of a lever
3. Pulleys
• Single pulleys function to change effective
direction of force application
which class level is most common in human body?
Third-Class Levers
Joint motion is resultant of
- A muscle contraction
• Drawing a distal segment more proximal
• The distal segment will rotate about the
center of the joint
relaxation def.
As the matrix of the segment reaches equilibrium,
or a neutral position, the load necessary to
maintain the length of the segment will decrease
The relative motions of joints surfaces may include
- Gliding
- Rolling
- Spin
- Compress
- Distract
Strength def., what is it dependent on, what does it produce? center of rotation at?
Amount of force needed to contract a muscle
• Dependent on degree of resistance (a.k.a. load)
experienced
• Produces a rotation (torque)
• The center of rotation, fulcrum or axis, is created at the
point of muscle insertion
moment def.,
The force being applied plus the moment arm
• Moment arm = the distance from the center of the
joint to where the contracting muscle is attached
• i.e. (force x distance)
known as the stiffness of the structure
The amount of force necessary to bend an object
rapid stretch vs. slower stretch in terms of resistance
• Rapid stretch will be met with increased resistance
• The faster you squeeze the less water you get out
Biomechanics Principles
• Slower stretch will be met with less resistance
• The slower, longer the squeeze, the more
complete expression of fluid from within the
matrix
slower stretch known as CREEP
types of stress
Force can act upon a structure from various orientations • Tension acts to stretch • Compression • Shearing acts parallel to the surface • Bending acts to fold about an axis • Torsion twists about an axis
mechanical loading can cause
tissue deformation.
load = sum of all stresses
external applied forces
Produced from outside the body & originate from gravity, inertia, or direct contact • Ground reaction forces (GRF) • The force exerted by the ground on a body in contact with the ground
Internal applied forces
• Muscular, joint and skeletal actions of the
body during the execution of a given task
vertical load (internal applied force) def.
Summative weight transmitted
through the kinetic chain to the
ground
• Force that results from the resistance
between surfaces of two objects from
moving upon one another
friction
