Cumc Ot Kinesiology Lecture 1

the study of the anatomical, biomechanical and physiological interactions within the musculoskeletal system; inspired by work of Leonardo DaVinci

describes motion of a body without regard for the forces/torques acting on the body

describes linear motion of a body

describes angular motion of a rigid body about some pivot point (axis)

tool used to measure/quantify rotation of joints in degrees

pivot point for angular motion; always perpendicular to the plane of motion

1. vertical

2. medial-lateral

3. anterior-posterior

rotary motion that occurs in the sagittal plane about a medial-lateral axis of rotation

rotary movement that occurs in the frontal plane about an anterior-posterior axis of rotation

rotary movement that occurs in the horizontal plane about a vertical axis of rotation

Depicts the number of independent movements allowed at a joint corresponding to angular motion in the 3 cardinal planes

the small degree of translation that can occur in synovial joints and occurs in linear directions (e.g. anterior-posterior, superior-inferior); the amount of this motion is used to test for the integrity of ligaments and to detect joint instability

when the distal segment of an extremity rotates on the proximal segment; ex: bringing hand to mouth, reaching forward with UE, putting arm behind back, crossing leg, advancing limb during gait

when the proximal segment of an extremity rotates on the distal segment; ex: squatting down, push/pull ups, standing up

describes the motion that occurs between the articular surfaces of joints during movement

remain centered and in full opposition during movement

What 3 factors ensure the stability of joints?

during movement the articular end of the rotating bone rolls, and the articular surface simultaneously slides, against the opposing bone's articular surface

_______ is not the same as translation!

position where joint surfaces "fit best" (i.e. maximally congruent); occurs near end of ROM where capsuloligamentous structures are taut

all positions other than the closed-packed position

describes the effect of forces on a body; a force can be a push or a pull that can produce, arrest or modify movement; forces provide the ultimate impetus for movement and stability of the body; forces that act on the body can be internal or external

gravity, external load or physical contact from others (e.g. therapist doing manual muscle test)

active or passive forces produced within the body; muscle activation, tension in periarticular connective tissues

the attraction of the mass of the earth for the mass of objects; most consistent force encountered by the body

point of application of gravity (line of gravity); during movement it changes constantly

can be manipulated by changing the position of your body or by moving in a plane that is the same as the direction of gravity

for an object to be stable, the line of gravity must fall within the base of support; the closer the center of gravity is to the base of support, and the larger the base of support is, the more stable the object is

a force acting at some distance from the axis of rotation of a joint is converted into a ______, which then has the potential to cause rotation of the joint; a product of a force and its moment arm

the distance between the axis of rotation and the application of force

T = F x MA

the product of the internal force (muscle) and the internal moment arm (the muscle's moment arm)

the product of the external force (gravity, weights, etc.) and the external moment arm

total force of all the fibers of a muscle is often represented as a single line of action (resultant muscle action line)

a portion of the overall force acts perpendicular to the long axis of the bone and will therefore contribute to ________ of the joint

a portion of the overall force acts parallel to the long axis of the bone and will almost always cause __________ of joint surfaces

________ force is almost always much larger than the rotational component

the potential of a muscle to create a torque (i.e. cause rotation) in a particular direction and plane

1. determine the degrees of freedom at the joint

2. determine how the muscles line of action crosses the axis(es) of rotation of the joint

a rigid bar suspended across a pivot point

the relative moment arm length possessed by a particular force

axis of rotation is between the opposing forces

axis of rotation is located at one end of a bone; the internal force (muscle) always possesses greater leverage than the external force

as opposed to the second class, the external force always has less leverage than the internal force (muscle); most common lever in the MSK system

the ratio of the internal moment arm to the external moment arm; measure of the efficiency of the lever

muscle pays the price in force requirement by acting so close to the joint's axis (lots of force required for a small amount of weight); the advantage is that we have a much larger potential for rotation (we can make a full fist)

normal tissue is able to adequately resist changes in its shape within a limit (disease or trauma can change this limit)

measure of the internal resistance generated as a tissue resists its deformation (e.g. while lengthening); types: compressive, tensile, & shear

magnitude of tissue deformation; ratio of tissue's deformed length to its original length

the ratio of stress/strain in connective tissue

if the limit for the physiologic range in which connective tissue can tolerate stress/strain is exceeded, __________ occurs and the CT will be irreversibly damaged and eventually fail

most tissues in the body exhibit this property; tissues exhibit changes in the stress-stain curve as a function of TIME (rate & duration); mechanical properties of connective tissue change depending on how fast or how slow (rate) length change occurs; faster the stretch, the greater the resistance, slower the stretch=less resistance

this property dictates that if stress is held constant, the strain increases with time; forms the basis for the use of dynamic splints to restore joint mobility

stress on the tissue is held constant (from the pull of a rubber band) for 30 mins; over that TIME, the amount of strain (i.e. change in length) in the tissue will increase

this property dictates that if strain is held constant, the stress decreases over time; forms the basis for the use of static progressive splints to restore joint mobility

set the strain rate (i.e. degree of elongation) to a point and leave it 30 mins; over that TIME, the amount of stress (i.e. internal resistance to elongation) in the stretched tissue will decrease