Exam #1 - Biomechanics Flashcards
closer to the head
Superior/Cranial
The lungs are ____ to the diaphragm
The lungs are superior to the diaphragm
Closer to the feet
Inferior/Caudal
Toward the front of the body
Anterior/Ventral
Toward the back of the body
Posterior/Dorsal
Toward the midline of the body
Medial
Away from the midline of the body
Lateral
Closer to the trunk
Proximal
Away from the trunk
Distal
Toward the surface of the body
Superficial
Away from the surface of the body toward the inside of the body
Deep
The liver is ____ to the diaphragm
The liver is inferior to the diaphragm
The sternum is ____ to the heart
The sternum is anterior to the heart
The vertebrae are ____ to the heart
The vertebrae are posterior to the heart
The humerus is ____ to the radius
The humerus is proximal to the radius
The scaphoid is ____ to the radius
The scaphoid is distal to the radius
The pectoralis major is ____ to the pectoralis minor
The pectoralis major is superficial to the pectoralis minor
Branch of mechanics that describes motion of a body without considering the forces that produce motion
Kinematics
Primary variables of kinematics (3)
- Position
- Velocity
- Acceleration
Movement of the body is either considered to be
Active or Passive
Movement produced by muscle activation (e.g. lifting a glass)
Active movement
Produced by a source other than muscle activation (e.g. gravity)
Passive movement
Describes motion of the bones relative to the 3 cardinal planes of the body (e.g., anatomical position)
Osteokinematics
What are the 3 cardinal planes of the body?
- Sagittal Plane
- Frontal Plane
- Horizontal Plane
Runs parallel to the sagittal surture & divides into right & left halves
Sagittal Plane
Runs parallel to the coronal surture & divides into front & back halves
Frontal Plane
Runs parallel to the horizon & divides into upper & lower halves
Horizontal Plane
What motions are performed in the Sagittal Plane? (6)
- Flexion/Extension
- Dorsiflexion/Plantarflexion
- Forward & Backward Bending
What motions are performed in the Frontal Plane? (7)
- Abduction/adduction
- Lateralflexion
- Ulnar/radialdeviation
- Eversion/inversion
What motions are performed in the Horizontal Plane? (3)
- Internal (medial) rotation
- External (lateral) rotation
- Axial rotation
**Bones rotating **around a joint in a plane of motion that is perpendicular to an axis of rotation
Osteokinematic motion
A pivot point for angular motion, usually located where zero motion occurs within the rotating body
Axis of rotation
An axis is typically located through the ____ member of a joint
An axis is typically located through the convex member of a joint
What is the axis of rotation for the Sagittal plane?
Medial-Lateral
What is the axis of rotation for the Frontal plane?
Anterior-Posterior
What is the axis of rotation for the Horizontal plane?
Vertical
- Number of independent direction a joint is allowed to move
- Considers translational & angular movements
- 3 cardinal planes of motion
Degrees of freedom
- Passive translation of a joint due to the normal laxity within a joint
- “Joint play”
Accessory Motion
Movement at a joint can be:
- ____ segment rotating about a fixed ____ segment
- ____ segment rotating about a fixated ____ segment
- Proximal segment rotating about a fixed distal segment
- **Distal ** segment rotating about a fixated proximal segment
Combination of several successively arranged joints constituting a complex motor unit
Kinematic chain
Open Kinematic Chain
- Movement of one joint is ____ of the other joints in the chain
- Distal segment of the kinematic chain is ____ fixed & ____ to move
- Movement of one joint is independent of the other joints in the chain
- Distal segment of the kinematic chain is not fixed & able to move
Closed Kinematic Chain
- Movement of one joint ____ the others in chain to move in a predictable manner
- Distal segment of the kinematic chain is ____ & ____ ____ to move
- Movement of one joint causes the others in chain to move in a predictable manner
- Distal segment of the kinematic chain is fixed & not able to move
Movement of the joint surfaces relative to one another
Arthrokinematics
- Improves congruency (fit)
- Increases surface area (dissipates contact forces)
- Guides motion between bones
Concave-Convex Relationship
Multiple points along one rotating articular surface contact multiple points on another articular surface
Example: A tire rotating across a stretch of pavement
Roll (rock)
A single point on one articular surface contacts multiple points on another articular surface
Example: A non-rotating tire skidding across a stretch of icy pavement
Slide (glide)
A single point on one articular surface rotates on a single point on another articular surface
Example: A toy top rotating on one spot on the floor
Spin
A separation of 2 joint surfaces
Example: Placing your hands together & pulling them apart
Traction
A decrease in space between 2 joint surfaces
Example: Pushing your hands together
Compression
- Convex member rolls & slides in opposite directions
- Convex bone is moving
Convex-on-Concave
- Concave member rolls & slides in same directions
- Concave bone is moving
Concave-on-Convex
The convex or concave member spinning on a singular point on a given articular surface
Spin
Branch of mechanics that describes the effect (causes) of forces on the body (gravity, toque, etc.)
Kinetics
The position of a moving object in terms of its acceleration, velocity and other aspects
Kinematics
Newtons 2nd law (F = ma) is associated with what branch of mechanics
Kinetics
____ or ____ that can produce, arrest or modify movement
Push or pull that can produce, arrest or modify movement
Two major classifications of Kinetics
Internal & External forces
Internal forces are produced from structures located ____ the body
Internal forces are produced from structures located within the body
External forces are produced by forces acting ____ the body (gravity, physical contact)
External forces are produced by forces acting outside the body (gravity, physical contact)
Forces (Loads) that move, fixate, or stabilize the body can also ____ & ____ the body
Forces (Loads) that move, fixate, or stabilize the body can also deform & injure the body
A rotatory force that rotates an object around an axis of rotation in a plane perpendicular to the axis of rotation
Torque
The perpendicular distance between the axis of rotation of the joint & the force is called a
moment arm
Product of a force and its momentum arm
Torque
A simple machine consisting of **a rigid bar that can rotate about an axis **
Lever
3 basic components of a lever
- Fulcrum
- Resistance arm
- Force arm
Axis of rotation
Fulcrum
Perpendicular distance from axis to resistance force
Resistance arm
Perpendicular distance from axis to applied force
Force arm
Axis is between the force and resistance
Mechanical Advantage = > or < than 1
1st class lever
Resistance is between the axis and force
Mechanical Advantage = Greater than (>) 1
2nd class lever
Force is between the axis and resistance
Mechanical Advantage = Less than (<) 1
3rd class lever
- Force-amplifying effectiveness of a simple machine
- Ratio of output force to input force
Mechanical Advantage
A time dependent property of non-contractile soft-tissue that initially resists deformation, such as a change in length, of the tissue, but if sustained, allows a change in length of the tissue & then enables the tissue to return gradually to its pre-stretched state after the stretch force has been removed
Viscoelasticity
Mechanical properties of connective tissue in response to stresses & strains (5)
- Crimp
- Plastic deformation
- Force (stress) relaxation
- Creep
- Stress Response
How do you find mechanical advantage?
Effort Arm Length (Ea) divided by Load Arm Length (La)
- Anatomical state of collagen where the fibers present wavy in orientation
- Major factor behind viscoelastic properties
- 1st line response to stress
- Primary in ligaments, tendons & joint capsules
Crimp
Occurs when a tissue remains deformed & does not recover its prestress
- Microfailure has ensued
- Collagen fibers are capable of a 3% increase in length before microscopic failure
Plastic Deformation
Indicates the decrease in the amount of force needed to maintain a tissue at a set amount of displacement or deformation over time
Force (stress) - relaxation
The ability of a tissue to deform over time while a constant load is imposed
Creep Response
- Exercises may be used to change the physical properties of both muscles/tendons and ligaments
- Both are capable of adaptation to external loads by increasing in strength
Stress response
Cyclic Loading & Connective Tissue Fatigue
Repetitive loading of tissues ____ heat production & may cause failure below the ____ ____
Repetitive loading of tissues increases heat production & may cause failure below the yield point
- Between the 2nd & 7th ribs
- The medial border is about 6cm lateral to the spine
Scapular position
- 135° angle of inclination between shaft & head
- 30° retroverted relative to the distal humerus
Humeral head orientation
Osteological relationship - directed anterolateral in the scapular plane & slightly rotated
Glenoid fossa
Osteological relationship - directed superomedial & retroverted (tilted posterior/back)
Humeral head
What is the functional significance of the scapular & humeral orientation?
Promoting function & stability
Scapulohumeral Rhythm
2:1
* 120° of GHJ abduction
* 60° of scapulothoracic upward rotation
Upward rotation of the scapula during full shoulder abduction is the result of…
- elevation at the SCJ
- upward rotation at the ACJ
During shoulder abduction the…
- clavical retracts at the SCJ
- scapula posteriorly tilts & ER
- clavical posteriorly rotates around its own axis
- glenohumeral joint ER
On average, women have a ____ carrying angle than men (~2°)
On average, women have a greater carrying angle than men (~2°)
- Natural frontal plane angle made during extension of the elbow
- Normally: 13° (+/-6°)
Normal cubitus valgus
Carrying angle of (greater) >20-25°
Excessive Cubitus Valgus
- Carrying angle (less) <5°
- Forearm deviated toward the midline
- “Gunstock deformity”
Cubitus Varus
The anterior trochlear groove determines the ____ that the humerus moves in ____ ____
The anterior trochlear groove determines the position that the humerus moves in full flexion
relative lengths of the distal surfaces of the radius and ulna
increased ulnar variance
the ulna is abnormally shortened compared to the radius
decreased ulnar variance
increased ulnar variance is a result of
active pronation
decreased ulnar variance is a result of
active supination
range of motion (functional arc) at the elbow typically needed to perform daily activities
30°-130° of flexion
A healthy person averages between ____° beyond neutral extension through ____° of flexion of the elbow
A healthy person averages between 5° beyong neutral extension through 145° of flexion
A healthy person generally allows 0 to 85° of ____ and 0 to 75° of ____ of the forearm
A healthy person generally allows 0 to 85° of supination and 0 to 75° of pronation of the forearm
The 100° functional arc of the forearm
0° neutral position thumb pointing straight up
Primary sources of carpal instability
- joint laxity
- rupture of specific ligaments
static carpal instability is demonstrated at
static carpal instability is demonstrated at rest
dynamic carpal instability is demonstrated only during…
free or resisted movement
ulnar deviation of fingers in rheumatoid arthritis
“zigzag” deformity
form of carpal instability
dorsal tilt of lunate
dorsal - top of hand
dorsal intercalated segment instability
form of carpal instability
volar tilt of lunate
volar - palm of hand
volar intercalated segment instability
form of capal instability
small bones of the wrist shift out of position
ulnar translocation of the carpus
