Musculoskeletal Biomechanics Test Review

Anterior

Front

Posterior

Rear

Lateral

Side

Medial

Midline of body

Distal

Away from origin

Proximal

Toward origin

Flexion

Bending of joint

Extension

Straightening of joint

Internal Rotation

towards body's midline

External Midline

Away from body's midline

Abduction

Away from midline

Adduction

Towards midline

Mesenchymal stem cells

Multipotent stem cells found in bone marrow. Important for making and repairing skeletal tissues.

Osteoblasts

Cells that build new bone (in bone)

Osteoclasts

Cells that eat old bone (in bone)

Osteocytes

Cells in the bone that maintain bone tissue by sensing mechanical stress (in bone)

Bone matrix

made up of type 1 collagen which provides flexibility and tensile strength. Inorganic component: hydroxyapatite which gives bone hardness and compressive strength

Cartilage cell type

chondrocyte

Chondrocyte components

type 2 collagen, aggrecan

cartilage vasculatrity?

low

bone vascularity?

high

muscle cell type?

fiber

components of muscles?

contractile proteins, actin, myosin

muscle vascularity?

high

tendon/ligament cell type?

fibroblast

tendons

between muscle and bone

ligament

between bone and bone( ACL is example)

components of tendons/ligaments

type 1 collagen, water

Vascularity of tendons/ligaments?

moderate/high

fibrocartilage cell type?

fibroblast, condrocyte

components of fibrocartilage?

type 1 and 2 collagen, water, some aggrecan

vascularity of fibrocartilage?

moderate

Where is fibrocartilage?

miniscus, labrum

DOF of point in 2d

2 dof

DOF of point in 3d

3 dof

Holonomic

Constraint on position

non-holonomic

constraints on velocity or acceleration

scleronomic

if equations of constraints do not contain time as a explicit variable

rheonomic

function of time

mobility

how many variables a system requires to define a position

joint

connection of two bodies

hinge joint 3d

5 constraints

revolute joint 3d

5 constraints

sliding joint 3d

5 constraints

condular joint (knee) 3d

4 constraints

ball and socket joint 3d

3 constraints

hinge joint 2d

2 constraints

revolute joint 2d

2 constraints

sliding joint 2d

2 constraints

condylar joint 2d

1 constraints

allometry

growth of body parts at different rates, resulting in a change of body proportion

Wolff's law

bone adapts to load. an increased load leads to increased bone

gait analysis input data

x, y , z position of markers over time

gait analysis output data

joint angles

plantarflexion

toes point downwards and heels rise

dorsiflexion

backward bending or flexing of foot

joint reaction forces and moment=

muscle forces and soft tissue stretch

anthropometry

scientific study of measurements and proportions of the human body

2D

links* 3

3D

links* 6

how can anthropometry be used?

identify of talented athletes, assess and monitor growing atheletes

Anthropometry variables

length, mass, moment of inertia, radius of gyration

muscle types

cardiac, smooth, skeletal

% bodyweight that is skeletal muscle

40-50%

number of skeletal muscles

430

muscle function

dynamic motion, static support(posture), protection(shock absorbing)

muscle structure

muscle>fascicles>fibers>myofibril>sarcomere

muscle fiber

individual cells that make up muscle tissue, responsible for generating movement

sarcomere

contractile unit of muscle fiber made up of actin and myosin

actin

thin filament

mysoin

thick filament

electromyography

EMG measures electrical current in muscle

latency

delay between stimulation and response

tetanus

maximum frequency beyond which no further contraction is possible

contractile element

actin/myosin

elastic element in series

tendon

elastic element in parallel

connective tissues

motor unit

fundamental functional unit of skeletal muscle, consisting of motor neuron and all fibers innervated.

motion

central nervous system sends signal to motor unit and the muscle shortens and applies force on bone which generates movement

concentric contraction

shortening of muscle causes joint movement

eccentric contraction

lengthening of muscle decelerates joint movement

isometric contraction

contraction of muscle with no movement

which contraction has greatest force?

eccentric> isometric> concentric

type 1 fiber

slow contraction

type 2 a

moderately fast contraction

type 2 b

fast contraction, anaerobic (sprinters and weight lifters)

muscle cramps

muscle contracts and cannot relax, acts on motor units, not individual fibers