Biomechaincs lecture 6 linear forces

resistive force examples

- eccentric tension - Resistance of connective tissue to being stretched -contact forces = bone to bone or other - Viscosity of muscle tissues and joint capsules.

Compression

A force that pushes on or squeezes a material.

muscular redundancy

Different muscles perform the same action

motive force

Force that causes a change in motion of a system (e.g., body, body segment, object).

angle of attachment

angle between a muscle and the bone to which the muscle inserts

right horizontal or orientation of angle

angle indicating the direction of force

joint angle

angle indicating the position of two jointed body segments relative to each other

stabilizing

component is parallel to the bone lever and pointing towards the joint axis of rotation

Motive (rotary)

component that is always perpendicular to the bone lever

foot pressure

compression equals the measure of

10,000 N

failure point at a human vertebra is at about what compressive force

resistive force

force that opposes or resists movement of a system within a frame of reference

spondylolisthesis

forward slipping of one vertebra over another involves bilateral fracture of the pars interarticularis. The defect causes instability and allows the superior vertebra to slip anteriorly

Spondylolysis

fracture of pars interarticularis involves a fracture of the pars interarticularis

Destabilizing (dislocating) component

is parallel to the bone and pointing away from the joint axis of rotation

Motive component

perpendicular to the bone where the muscle inserts

destabilizing component

pointing away from the joint axis

stabilizing component

pointing towards the joint axis

motive force examples

•Concentric tension of muscles attached to the segment. •Recoil of elastic connective tissue to being stretched (tendons, ligaments).

relative joint angle

(intersegmental angle) expresses the angle between two body segments

degrees

(pi/180) = Radians

absolute joint angle

(segmental angle) expresses the segmental position relative to the right horizontal

Magnitude of force

The length of a force vector represents the