Week 2 Flashcards
What are the 5 components of kinematics?
List force types
Centrifugal vs. Centripetal Forces
Drag Forces
Buoyancy
Gravity
Bending Forces
Pressure forces
Friction vs. Shear Forces
Reaction Forces
What are the 3 laws of motion?
By Isaac Newton
- Law of Equilibrium/Inertia
- Law of Acceleration
- Law of Reaction
Define Newton’s first law and provide an example
Law of equilibrium/inertia
◦Defined: “An object will remain at rest or in uniform motion unless acted upon by an unbalanced force”
◦ Sum of all forces equal zero
◦ Examples: Static posture standing and sitting, sleeping, dancer or ice skater spinning, isometric muscle contraction
Which forces are + and -?
1) +
2) +
3) -
4) -
What is happening in this example?
Tug-of-war. The system is in equilibrium because the sum of the forces in the horizontal direction is zero. No movement to the left or the right can occur.
Which muscles act during an anterior pelvic tilt? Posterior pelvic tilt?
Anterior: iliopsoas, erector spinae, rectus femoris
Posterior: gluteus maximus, hamstring, rectus abdominis, external oblique
Define Newton’s second law and provide an example
Law of acceleration
Definition: The forces acting on the body will not yield 0; net unbalanced forces create movement.
◦ Net unbalanced linear =translation motion (glide)
◦ Net unbalanced torque=rotation motion (roll/spin)
◦ E.g., patient actively falling, muscle contraction, walking, running
Define Newton’s third law and provide an example
Law of reaction
Definition: For every action, there is an equal and opposite reaction. Opposite force equal in magnitude and direction.
Example: Ground reactive force
Explain
Reaction forces through the normal knee
While walking, a force equal to about three times body weight passes medial to the knee joint, creating a varus torque at every step
List and explain the 3 forces
The term (force = stress = load)
1) tensile force: pulling apart/away
2) compressive force: pushing together/inward
3) shear force: parallel force of one structure going past another
What are the types of forces?
1) Internal forces (produced from within):
A) muscle
B) ligament
C) joint reaction
2) External forces:
A) gravity
B) ground reaction
C) friction or resistance
What is the difference between a scalar and a vector?
1) scalar: Magnitude
Ex: gait speed (how fast)
2) vector: Magnitude and direction
Ex: gait velocity (how fast in a specific direction)
How does the force of gravity and the force of muscle work?
1) Gravity: force = pulls things downward (line going down towards Earth’s center). Magnitude: 9.8 m/s^2
2) Muscle: force = pulls in many different directions to counteract gravity or other external forces.
It is individual forces (a combo of all muscle striations) that combine to produce a resultant force
What is needed for motion to occur? What is needed for static equilibrium to be maintained?
1) Motion occurs with the net sum of all forces are unbalanced and do not equal ZERO.
2) Static equilibrium is maintained when the sum of multiple forces will yield ZERO.
Explain the SAID principle, when to use it, and provide examples
Specific Adaptation to Imposed Demands
Definition: The human body will adapt to imposed demands (stress or force). If the load increased or decreases the morphology of the structure will change. “You lose it if you don’t use it”
When to use: Use this principle to improve your understanding of when to apply or reduce force to a specific connective (soft) tissue structure.
Ex:
1) Loading or unloaded a healing fracture, strain or sprain; WB status
2) When to completely immobilize; Safety and protection of a structure
3) When to be aggressive or increase load
4) How to progress a soft tissue structure after immobilization or injury.
Describe each region
1) Toe: barley moving the joint
2) Elastic region: applying force but its not strong enough for permanent change
3) plastic region: there will be change, it does not return to original shape
4) compromise, because it causes trauma, tears, fracture… failure
5) yield point: exact point from no lasting to lasting change (in muscle, ligament, capsule,…)
Where is the target area in the load/deformation curve?
after the yield point but not close to the failure point
Explain the viscoelasticity principle
- What is a viscoelastic material?
◦ “viscosity”=behavior is dependent on time, rate and history; Resistance to flow
◦ “Elastic”=ability to return to original length, shape, and structure. Based on the properties of elastin inside of that particular structure. - Creep—sustained change to a viscoelastic structure over time if force remains constant to the same object.
◦ E.g. weighted hang or compressive gradual loading for bone. - Hysteresis—The ability of a soft tissue structure to dissipate heat to change the morphology of its structural make-up (composition).
◦ Remember that the viscous portion of soft tissue relates to water.
◦ Viscosity decreases as temperature rises
◦ Most common in ligaments and tendons
What are the phases of acute wound healing?
1) hemostasis
2) inflammation
3) proliferation
4) remodeling
List the planes of motion with their axis
1) sagittal plane: flexion/extension, forward bend, SLR
Axis: X-axis “medial/lateral” (creates sagittal plane movement) (sometimes called coronal/frontal axis)
2) coronal/frontal plane: abd/add, side-step, lateral bending
Axis: A-P axis (creates coronal/frontal plane movement) (sometimes called Z-axis or sagittal axis)
3) transverse plane: ER/IR, trunk rotation
Axis: vertical axis (creates transverse plane movement) (sometimes called Y-axis, transverse axis)
What POM and AXIS are in this motion?
POM: sagittal
AXIS: X-axis
Are the 3 discussed POM the only ones?
No, many motions will result across multiple planes
define center of gravity
The point at which all the body’s mass seems to be concentrated; the balance point of a body; the point around which the sum of all the torques of the segmental weights is equals to zero
Define line of gravity
Vector (visual Representation) gravity as an external force always acting on the human body.
Vertical line that passes through your COG into the ground.
Historically referred to as a “plum bob” or “plumb line”
Currently used as a reference for posture, center of mass and equilibrium and balance training
Basis for modern developments in medicine such as force plates
Define moment arm
perpendicular distance from line of force to the axis
Requires an understanding of anatomy, muscle attachments and normal kinematics available at the particular joint.
Define external moment
◦ Determined by location of LoG in relation to axis of motion
◦ If the log passes through the joint, no external gravitational torque
◦ If at a distance, external gravitational moment is created
◦ If anterior to joint, causes proximal segment to move anteriorly
Define musculoskeletal levers
Decreasing muscle length = increasing muscle moment arm
Within the body, internal and external forces produce torques through a system of bony levers.
Internal and external torque (static analysis)
what is the order of a 1st class lever?
effort, axis, load (or reverse order)
M Ad = 30/10 = 3
In a first-class lever system, Effort Arm distance may be greater than Resistance arm (RA), smaller than RA, or equal to RA
What is the order of a 2nd class lever?
axis, load, effort
What type of lever? Explain
Further away the effort is from the fulcrum and the load the greater the mechanical advantage of the lever.
A second class lever, the effort arm is always larger than the resistance arm.
What type of lever? Explain
3rd class lever
Such levers do not have good mechanical advantage. In fact they have mechanical disadvantage.
What is the 1) freedom of motion, 2) axis, 3) function, 4) region uniques features for labeled structures (A, B, C)
1) GH Joint
* Type: Ball-and-socket joint
- Freedom of Motion: Triaxial (three degrees of freedom)
- Axis:
* Sagittal axis (flexion/extension)
* Frontal axis (abduction/adduction)
* Vertical axis (internal/external rotation) - Function: Allows a wide range of motion for the upper limb, essential for tasks requiring overhead, reaching, or rotational movements.
- Region Unique Features:
* High mobility but low stability.
* Supported by the rotator cuff muscles and the glenoid labrum.
2) Humeroulnar Joint
* Type: Hinge joint
- Freedom of Motion: Uniaxial (one degree of freedom)
- Axis: Sagittal axis (flexion/extension)
- Function: Provides stable flexion and extension of the forearm, crucial for lifting and pushing activities.
- Region Unique Features:
* Strong collateral ligaments support.
* Trochlear notch of the ulna articulates with the trochlea of the humerus.
3) Tibiofemoral Joint
* Type: Modified hinge joint
- Freedom of Motion: Biaxial (flexion/extension with slight rotation)
- Axis:
* Sagittal axis (flexion/extension)
* Vertical axis (internal/external rotation, minimal) - Function: Weight-bearing and mobility in walking, running, and squatting.
- Region Unique Features:
* Contains menisci for shock absorption.
* Stabilized by the ACL, PCL, and collateral ligaments.
What is the 1) freedom of motion, 2) axis, 3) function, 4) region uniques features for labeled structures (D, E, F)
D) Talocrural Joint
* Type: Hinge joint
- Freedom of Motion: Uniaxial (one degree of freedom)
- Axis: Sagittal axis (dorsiflexion/plantarflexion)
- Function: Provides stability and motion during walking and running; critical for ankle mobility.
- Region Unique Features:
* Articulates between the tibia, fibula, and talus.
* Mortise-and-tenon configuration provides stability.
E) Radiocarpal Joint
* Type: Ellipsoid (condyloid) joint
- Freedom of Motion: Biaxial (two degrees of freedom)
- Axis:
* Sagittal axis (flexion/extension)
* Frontal axis (radial/ulnar deviation) - Function: Facilitates wrist movements essential for grip, manipulation, and precision tasks.
- Region Unique Features:
* Articulation between the radius and the scaphoid/lunate.
* Strongly supported by ligaments to maintain stability.
F) Coxofemoral Joint
* Type: Ball-and-socket joint
- Freedom of Motion: Triaxial (three degrees of freedom)
- Axis:
* Sagittal axis (flexion/extension)
* Frontal axis (abduction/adduction)
* Vertical axis (internal/external rotation) - Function: Provides stability and mobility for activities like walking, running, and jumping.
- Region Unique Features:
* Deep acetabulum enhances stability.
* Ligamentum teres supplies blood to the femoral head.
Solve
Solve
What are the levels from micro to macro healing and movement restoration?
How many structural features of the knee region could you assess through palpation skill?
