Biomechanics Exam 1

Chapter 1

• bio= life

• mechanics= the study of the actions of forces (both internal muscle forces and external muscle forces

• Biomechanics is the of the mechanical aspects of living organisms.

  Sub-branches of Biomechanics

• Statics is the study of systems in constant motion. (including zero motion)

• Dynamics is the study of systems subject to acceleration

• Kinematics is the study of the size, sequencing, and timing of movement, without regard for the forces that cause or result from the motion.

• Mechanics is the study of the actions of forces (Force can be thought of as a push or pull acting on a body.)

• Kinetics is the study of forces, including internal forces (muscle forces) and external forces (the forces of gravity and the forces exchanged by bat and ball).

• Qualitative: pertaining to quality without the use of numbers. (ex; strong, skillful, agile, flexible, fast)

• Quantitative: involves numbers (ex; he missed the mat by 30 cm)

• Kinesiology is the study of human movement and how it affects the body and overall health.

Chapter 2

Forms of Motion

• Linear motion: motion in a line that’s straight or curved

• Rectilinear motion: Motion in a straight line

• Curvilinear motion: motion along a curved line

• Angular motion: rotation around a imaginary line known as the axis of rotation (throwing a football or baseball) Motion at most human body joints is angular

  Forms of Motion

• General motion: combination of linear and angular motion components

• Mechanical system a body or a portion of a body that is deliberately chosen as the system to be analyzed.

  Anatomical reference position is the starting point for all body segment movements. It is standing erect with all body parts facing forward.

• Function Position: standing erect with arms at your side facing forward.

  Directional Terms

• Superior: Closer to the head

• Inferior: Farther away from the head

• Anterior: Toward the front of the body

• Posterior: Toward the back of the body

• Medial: Toward the midline of the body

• Lateral: Away from the midline of the body

• Proximal: Closer in proximity to the trunk

• Distal: At a distance from the trunk

• Superficial: Toward the surface of the body

• Deep: Inside the body away from the surface

  Anatomical Reference Planes

• Sagittal Plane: forward and backward movements occur in this plane.

• Frontal plane: where lateral movements occur

• Transverse Plane: the plane for rotational movements

  Reference Axes

• Longitudinal Axis: directed vertically and around which rotational movements occur

• Anteroposterior axis: directed along the sagittal plane and around which rotations in the frontal plane occur

• Mediolateral axis: directed along the frontal plane and around which rotations in the sagittal plane occur

  Joint Movement Terminology

• Sagittal Plane: Flexion,Extension, Hyperextension, Dorsiflexion, Plantar flexion

• Frontal Plane movements: abduction, adduction, lateral flexion, elevation, depression inversion, eversion, radial ulnar deviation.

• Transverse plane movements: left and right rotation, medial, lateral rotation, supination, and pronation, horizontal abduction and adduction.

• ulna on the pinky side radius on the thumb side of hand

  Other Movements

• Circumduction: combines all movements in one (plank)

• Muscle is fully ingaged but there is no change in the range of motion not moving(plank)

• isotonic is a muscle contraction that gets easier and is moving (bicep curl)

• isokinetic controlled by some other force. Fully engaged the entire time.

Chapter 3

• Inertia: Tendency of a body to resist a change in its state of motion. (ex: a weight staying in place on the floor without being touched because of inertia)

• There is no way to measure this

• Mass: Quantity of matter composing a body (dog, tree, desk, basketball, human body)

  • Represented by m

  • Units are kg

  •The GREATER the mass of an object the more resistance to change it will have

• Mass is proportional to weight but mass is NOT related to size

• Force: A push or pull acting on a body

• characterized by its magnitude, direction, and point of application.

• The action of a force causes the body’s mass to accelerate

• F=Ma

• The unit is the Newton (N)

• 1N or 1lb

• Free body diagram: a sketch that shows a defined system in isolation with all of the force vectors acting on the system.

• Net Force: The single resultant force derived from the vector composition of all the acting forces

• The force that determines the net effect of all acting forces on a body

• when all acting forces are balanced, or cancel each other out, the net force is zero.

• Torque is the rotary effect of a force, the angular equivalent of force, and also known as a moment of force.

• Center of Gravity : The point around which a body’s weight is equally balanced in all directions no matter how the body is positioned. (COG)

• Point that serves as an index of total body motion

• Location of the center of mass determines how a body responds to external forces.

• Point at which the weight vector acts

• Center of Gravity is the same thing as the center of mass

• Weight: Gravitational force that the earth exerts on a body./ The point of application of the weight force is a body’s center of gravity

• wt.=ma^g (product of mass and the acceleration of gravity no matter what: -9.81 m/s²)

• Pressure: Force per unit of area over which the force acts

• Commonly used to describe force distribution within a fluid (blood pressure, water pressure)

• usually seen is psi, units are N/m²

• Stress: Force per unit of area over which the force acts

• Commonly used to describe force distribution within a solid

• Units are N/m²

• Volume: Space occupied by a body

• has three dimensions (width, height, and depth)

• Units are m³ and cm³

  (Ping Pong Ball vs Golf Ball)

• Density: Mass per unit of volume

• Units are kg/m³

• Specific weight: Weight per unit of volume

• Units are N/m³

• Compression: pressing or squeezing force directed axially through a body (think of movement of the bones directly on top of each other

• Tension: Pulling or stretching force directed axially through a body

• Shear: Force directed parallel to a surface (pivot shift motion, so the two body parts are moving in two opposite directions. think of acl tear)

• Bending: Asymmetric loading that produces tension on one side of a body’s longitudinal axis and compression on the other side

• Torsion: Load producing twisting of a body around its longitudinal axis

• Repetitive Loading: repeated application of a subacute load that is usually of relatively low magnitude

• Acute Loading: application of a single force of sufficient magnitude to cause injury to a biological tissue

Chapter 4: Human Bone Growth and Development

• Stiffness: A Stress/strain ratio; stress divided by the relative amount of change in shape (The Amount of load the bone can take before it breaks)

• Compressive Strength: The ability to resist pressing or squeezing forces

• 4 major building blocks of bone:

  1- Calcium Carbonate

  2- Calcium Phosphate

  3- Collagen

  4- Water

• Collagen contributes to flexibility and tensile strength (ability to resist tension in bone)

• Aging causes collagen to be progressively lost while the bone increases in brittleness

• Water content comprises 25-30% of bone weight, which can affect bone strength

• Bone porosity, which is the amount of bone volume filled with pores or cavities, also affects bone strength.

• Cortical bone: compact mineralized bone with low porosity; found in the shafts of long bones (outer part of bone)

• Trabecular (or cancellous) bone: less compact or spongy bone with high porosity;  found in the ends of long bones and the vertebrae (inner part of the bone)

• Bone is strongest in resisting compression and weakest in resisting shear

  Types of Bones

• Axial skeleton: (central)  found in you skull, vertebrae, sternum, and ribs

• Appendicular skeleton: (peripheral) bones composing the body appendages

  There are 206 bones in the human body

• The carpal and tarsals bones cubical in shape and are examples of short bones (ex- hand bones)

• The scapula is an example of a flat bone that protects organs and provides surfaces for muscle attachments

• All the scapula does is help the muscles and ligaments attach to aid in movement and protects your lungs. It is very thin.

•  Irregular bones, such as the axis, (the second cervical vertebra), have different shapes to serve different specialized functions.

• Atlas holds your head (C1)

• Axis is what the atlas spins on (C2)

• Long bones, such as the femur, form the framework of the appendicular skeleton. Long shafts and bulbous ends

• The epiphyses, or epiphyseal plates, are growth centers where new bone cells are produced until the epiphysis closes during late adolescence or early adulthood. (usually close by 18 but can go to age 25)

  Bone Growth and Development

• Bones grow in circumference by the inner layer of the periosteum, a   double-layered membrane covering  bone, building concentric layers of  new bone on top of existing ones

• Specialized cells called osteoblasts build new bone tissue and osteoclasts resorb bone tissue

• Osteoblasts (build up) and osteoclasts (break down) are continually building and resorbing bone, respectively.

• Increased or decreased mechanical stress leads to a predominance of   osteoblast or osteoclast activity, respectively.

• Hypertrophy basicalling means growth. Muscles and bones respond to this.

• Wolff’s law: Bones align and will adapt to the stress that is placed upon them.

• Your dominant hand has longer bones in it and with fatigue faster.

• Causes of diminished bone density: Lack of weight bearing exercise, Spending time in the water, (since the buoyant force counteracts   gravitational force), Bed rest, and Traveling in space outside of the earth’s  gravitational field

• Osteoporosis is a disorder involving decreased bone mass and strength with pain and one or more fractures resulting from daily activity. Type 1 hits women after age 50, type 2 women and men after 70

• Osteopenia= beginning of osteoporosis which done density has decreased