Exam 1

Kinesiology

kinematics and kinetics

two branches of biomechanics

kinematics

describes the motion of a body; amount, quality, velocity, pattern

kinetics

forces associated with motion; size, shape, weight

linear motion

all points of a body move the same distance and in the same direction

translation (translatory motion)

linear motion in which all parts of a rigid body move parallel to and in the same direction as every other point in the body

rotation (rotatory motion)

angular movement of a body in a circular path around some pivot point

axis of rotation

an imaginary line extending through a joint around which rotation occurs

osteokinematics

motion of bones relative to cardinal planes

active and passive

two types of internal forces/torques

human motion

rotation that collectively produces translatory motion of the entire body

Newton’s First Law (Law of Inertia)

a body remains at rest or at constant velocity until an external force/torque changes its current state

Newton’s Second Law (Law of Acceleration)

states force is the product of mass x acceleration; also states acceleration of a body is proportional to the force/torque causing it, occurs in the same direction as that force/torque, and is 1/mass of the body itself (ex: bigger body, more force/torque to move it)

Newton’s Third Law (Law of Action-Reaction)

states every force/torque will have an equal and oppositely directed force/torque (the idea of equilibrium)

static equilibrium

state of a body at rest in which the sum of all forces is zero

dynamic equilibrium

when an object moves at a constant speed, and all the forces on the object are balanced

magnitude, direction, point of application, spatial orientation

four factors that are used when visualizing forces

magnitude

the length of the shaft of the arrow

direction

indicated by the arrow head

point of application

where the base of the vector arrow contacts part of the body; can either be the mm attachment point (for internal forces) or the center of mass (for external forces/gravity)

spatial orientation

indicated by the position of the shaft of the arrows or the angle to the lever

collinear forces

forces that have a common line of action

resolved forces

one force is broken into two forces acting at 90 degrees to each other (parallel and perpendicular)

parallel components

provides compression or distraction to the joint (stabilize or destabilize); if this is the only force present, there is no motion at the joint

perpendicular components

force component that causes rotation/motion at the joint; is always 90 degrees from the axis of rotation

center of mass

this is estimated to be just slightly proximal to the midpoint

sacrum/S2

the center of mass of the human body lies approximately anterior to which vertebrae

force, distance, and axis of rotation

three things torque requires

F x d

formula for torque

first class lever

the axis of rotation is located b/t the external and internal forces in this lever system

second class lever

the external force is located in b/t the internal force and the axis of rotation in this lever system

third class lever

the internal force is located b/t the axis of rotation and the external force in this lever system

>1 or <1

the mechanical advantage of a first class lever

>1

the mechanical advantage of a second class lever

<1

the mechanical advantage of a third class lever

arthrology

study of the structure, classification, and function of joints

capsule, ligament, tendon, articular cartilage, fibrocartilage, bone

list the periarticular tissues (gross) in a joint

fibers, ground substance, cells

three fundamental components of connective tissue

collagen, elastin

two types of connective tissue fibers

stiff, strong, little elongation

characteristics of type I collagen

resists tension (stretch) more than compression (ligaments, joint capsules, and tendons)

function of type I collagen fibers

thinner, increased deformation, and consistency of shape

characteristics of type II collagen fibers

resist compression more than tension (hyaline cartilage at the end of bone)

function of type II collagen fibers

elastin

these fibers are present in varying amounts in CT and return to their original shape after deformation

GAG’s (glycosaminoglycans), water, solutes

three components of connective tissue ground substance

ground substance

water-saturated matrix or gel that is composed of GAGS, water, and solutes (fibrous protein fibers)

hydrophilic (swell and repel); negatively

Are GAGS hydrophilic or hydrophobic? Are they positively or negatively charged?

resist compression

function of GAGS

fibrous proteins

what lies within the ground substance and resists tension

chondrocytes (cartilage), fibroblasts (general), osteoblasts (bone)

three different types of connective tissue cells

synthesize, maintenance, and repair ground substance and proteins

connective tissue cell function

dense connective tissue, articular cartilage, fibrocartilage, bone

types of periarticular connective tissue

dense connective tissue

this type of connective tissue resists tension and can be irregular (multidirectional) or regular (near parallel orientation of fibers)

elastic energy

What type of energy is stored in stretched tissue?

articular cartilage

this is a specialized form of hyaline cartilage that is located over load-bearing surfaces of bone; it contains lots of collagen fibers and proteoglycan complexes (which means it is good at resisting loads)

True

T/F: articular cartilage is aneural and avascular.

distribute and absorbe compressive joint forces and decreases friction b/t joint surfaces

two functions of articular cartilage

fibrocartilage

composed of dense connective tissue (tensile strength) and articular cartilage (resilience and shock absorption)

shear and compressive

fibrocartilage tolerates which two types of forces

outermost

which fibers of fibrocartilage are vascularized

bone

this type of connective tissue is compact and highly organized, highly vascularized and innervated, and constantly being remodeled

support, leverage, protection, mineral storage, supplies new blood cells

five functions of bone

cancellous bone

this type of bone transfers load

compact bone

this type of bone resists compressive loads

Wolff’s Law

states bone is laid down in areas of high stress and reabsorbed in areas of low stress; form follows function

ligament, joint capsule, synovial membrane, articular cartilage, blood vessel, nerve, synovial fluid

seven parts of synovial joints

joint capsule

sleeve around the joint that connects bony partners and provides some stability and supports motion

synovial membrane

inner lining of joint capsule, permeable membrane that secretes synovial fluid, significantly decreases shear forces to articular cartilage with motion and also resists distraction of a joint

menisci

this structure is predominantly composed of type I collagen; it increases stability in a joint, distributes load and is a shock absorber, and decreases shear loads to articular cartilage

labrum

this is a circular fibrocartilage ring that is found in the shoulder and hip; it deepens the concavity of these joints and improves stability

convex member

the rounded member that is often larger than the socket/cavity it articulates with; the axis of rotation goes through this member

concave member

the depressed member of a joint that articulates with the rounded member; an example would be a cavity

1; flexion/extension

How many DoF do hinge joints have? What osteokinematic actions occur at this joint?

3; flexion/extension, AB/ADD, IR/ER

How many DoF do ball-and-socket joints have? What osteokinematic actions occur at this joint?

2; flexion/extension, AB/ADD (or radial/ulnar deviation)

How many DoF do ellipsoid joints have? What osteokinematic actions occur at this joint?

2; flexion/extension, rotation

How many DoF do pivot/trochoid joints have? What osteokinematic actions occur at this joint?

parallel

What direction does a spin motion occur in relation to the axis of rotation? (parallel or perpendicular)

0 (planar joints have no defined AoR or DoF); translation (bones sliding on each other)

How many DoF do planar joints have? What motion occurs at this joint?

2; AB/ADD, flexion/extension

How many DoF do saddle joints have? What osteokinematic actions occur at this joint?

2; flexion/extension, IR/ER

How many DoF do condyloid joints have? What osteokinematic actions occur at this joint?

opposite directions

When convex moves on concave, roll and slide occur in which direction?

same direction

When concave moves on convex, roll and slide occur in which direction?

muscle, fascicles, fibers, myofibrils, myofilaments, actin, myosin

muscle organization from macro to micro

fusiform

muscle type in which the muscle fibers run parallel to each other and to the tendon

pennate

muscle type in which the muscle fibers run oblique to the tendon

pennate

Which mm type has more mm fibers per given length of tendon?

increase in # of mm fibers leads to greater potential for internal force production

If the angle of pennation is greater, is there an increase or decrease in the number of mm fibers? How does this affect internal force?

sarcomere

the basic contractile unit of a mm fiber

actin and myosin

two main protein myofilaments found in sarcomeres; they are the active structures responsible for muscular contraction

a greater force is produced since more physiologic cross-sectional area would mean more mm fibers in that area

If the physiologic cross-sectional area is greater, is a greater or less force produced? Why (hint: # of mm fibers)

series elastic components

this elastic component distributes force b/t bone and mm

parallel elastic components

this elastic component are made of structural proteins and extracellular connective tissue

active insufficiency

this means there is too much overlap b/t actin and myosin

passive insufficiency

this means there is not enough overlap b/t actin and myosin

midpoint/mid-length

Where is greatest active force found when actively contracting the mm?

motor units

alpha motor neuron + all the mm fibers it innervates

Henneman Size Principle

states the smallest motor units are recruited first

all or none principle

states a motor unit fires or it does not

Law of Parsimony

states the nervous system tends to activate fewest mm fibers possible for activity (energy efficiency), single joint mm recruited for low power tasks, and avoidance of activating multi-joint mm

eccentric contraction

during this type of contraction velocity increases as forces increases

during this type of contraction velocity decreases as force increases