What is Bone?

A dynamic living tissue that is continually being modeled and remodeled by the forces acting on it.

 What are the primary functions of bone?

1. Provides a system of levers that can be moved by forces from muscles

2. Provides a skeletal framework that supports and protects other body tissue

simple machine

magnifies the force and/or speed of movement 

Skeletal system provides the levers and axes about which muscle generates                 

Other Functions of Bone

Composition of Bone

Calcium carbonate & calcium phosphate

which provide:

Flexibility and tensile strength

Anatomy of the Long Bone

Cortical Bone has                porosity

Cortical Bone is          % non-mineralized tissue

Cortical bone can withstand greater                 but less 

Trabecular bone has              porosity

Trabecular bone can undergo more              before fracturing 

Trabecular bone is also known as              

Trabecular bone is           % non-mineralized tissue

Provide limited gliding motions

Act as shock absorbers

Protect underlying organs and soft tissues

Provide large areas for muscle and ligament attachments

The ribs, ilium, sternum, and scapula are examples of what type of bone?

Form framework of appendicular skeleton 

Sesamoid bones do what?

Increase the angle of insertion of a muscle (moment arm)

Sesamoid bones

Irregular Bones do what?

Specialized functions 

The Skull, pelvis, and vertabre are examples of what type of bone?

Osteoblast do what? And by how?

Form bone - increase bone mass

by taking minerals from the blood and deposit them in the bone

Osteoclasts do what?

Cells that eat away (reabsorb) old bone

(decrease bone mass)

Mature osteoblasts that are no longer forming bone

Longitudinal Growth is when                    

Growth ceases after the closure of the epiphyseal plates and Epiphyseal plates expand, forming new cells, to increase length

Longitudinal Growth occurs when?

18-25 years old

Circumferential growth occurs when?

Continues throughout the lifespan

Osteoporosis is when             

Loss of bone density results in?

 a loss of stiffness

Results in a weaking of the bone

Osteoporosis causes a increase in what?

incidence of fracture

Causes of Osteoporosis are

Hormonal factors

Nutritional imbalances

Lack of exercise

Stress is

Force applied to deform a structure

Strain is

Deformation resulting from stress

Stress-Strain Curve does what?

Determines how materials respond to different loading conditions.

energy lost in a viscoelastic material

1. Tension
2. Compression
3. Shear

Compression force loads are caused by

Muscles

Gravity

External forces acting on long axis of bone

Tension force loads are caused by

pull of contracting muscle tendon

Tension forces occur where?

most often at an apophysis (bony outgrowth)

Shear force loads are 

Sliding or slipping forces

Bending forces produce

both compressive and tensile forces on either side of the bone, respectively

Torsional forces are 

Factors determining bone injury:

1. Critical strength of bone
2. Loading history
3. Rate of loading

What influences bone response to loading?

Magnitude

Frequency

Location

Variability

Direction

Rate of application

Duration

Synarthroses permit            but not            

shock absorption but not movement

Sutures are 

bone sheets bound at first by fibers

Syndesmoses are 

bones bound by dense fibrous tissue

Amphiarthroses joints are 

Cartilaginous joints that Attenuates shock and allows minimal motion

Synchondroses

joints held together by thin layer of hyaline cartilage

Symphyses

 thin plates of hyaline cartilage separated by a disc of fibrocartilage from the bone

Hinge joints allow movement in

 one plane (uniaxial)

one plane (uniaxial)

Condyloid joints allow movement in 

primarily in one plane but small amounts of movement in another planes

Ellipsoid joints allow movement in

 two planes (biaxial)

Ball and Socket joints allow movement in 

all 3 planes

Lose Packed has           injury risk due to          

Articular Cartilage is composed of          % water

Functions of Articular Cartilage

1.) Provide a nearly frictionless surface for load bearing            and movement

2.) Redistribute contact stress over a larger area

3.) Protect underlying bone

Curvilinear Motion

translation only

General Motion is a combination of what?

General Motion has translation and what?

Statics are the study of what?

Study of systems in state of constant velocity.

Dynamics are the study of what?

Study of systems not in steady-state motion

Kinematics is the  

Description of motion

Inertia is

Natural property of a body to resist a change in state of motion 

Newton’s 1st Law

Inertia

An object at rest will remain at rest…

An object in motion will remain in motion….

unless acted upon by an outside net force.

Newton’s 2nd Law

F=ma

Force

Newton’s 3rd Law

Action-Reaction

Centric forces result in              

Eccentric forces always result in                

First-Class Levers produce:

balanced movements when axis is midway between force & resistance (e.g. seesaw)

Second-Class Levers resistanve is between                

axis and force

Third-Class Lever are the 

Most common lever system in the human body

Musculoskeletal Lever System generally favor 

speed over strength.

Nervous system controls and monitors             

Brain and spinal cord

Branches of nerves that lie outside spinal cord

Tibial N. + Common Peroneal N.

Motor unit consists of 

Maintain Posture

Stabilize joints

Repetitive activities (typing, jogging)

Swimming

Bicycling

Sprinting

Jumping

Weight Lifting

1.) Number of fibers innervated by the motor unit

2.) Rate at which the motor unit discharges the impulse or action potential

Muscle force determined by…

Recruitment

Frequency

Synchronization?

Initial strength gains come from what?

neuromuscular adaptations

Specific 

Adaptations to

Impose

Demands

What are some limits of flexibility?

Joint Structure

Soft Tissue (Muscle, fat)

Ligament properties

What are the two basic types of fiber arrangment?

Parallel (Fusiform)

Penniform

Angle made by the fascicles and the line of action (pull) of the muscle.

An isotonic exercise in which the end of the chain is FIXED

The moment created by a muscle is dependent upon what 3 things:

Muscle Force

Moment arm

Angle of pull

What is the contractile unit of a muscle?

Myosin = Thick

Actin = Thin

muscles that contract Slower produce greater or less force than muscles that contract faster?

muscles that contract slower need to be more or less active as muscles that contract faster?

T=F•d

Levers

Wheel/axle

pulley

Gliding

hinge

pivot

condyloid

ellipsoid

saddle

ball-and-socket