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Intro to Biomechanics > Intro to Biomechanics > Flashcards

Intro to Biomechanics Flashcards

1
Q

Biomechanics definition

A
  • Application of mechanical laws to living structures

- Specifically to locomotor system of the human body

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2
Q

Walking definition

A
  • To move at a regular and fairly slow pace by lifting and setting down each foot in turn, never having both feet off the ground at once
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3
Q

Less energy for walking is required when

A
  • There is minimal displacement of the center of mass

- Each moveable segment functions ideally

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4
Q

Series of movements in walking is orchestrated by

A
  • Stable joints
  • Muscle actions
  • Angular momentum
  • Sequential kinematic activity
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5
Q

Components creating joint stability

A
  • Bones and joints
  • Ligaments and joint capsule
  • Neuromuscular activity
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6
Q

Bones/joints contribution to stability

A
  • Shape of bones

- Design of articular cartilage in bones

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7
Q

Ligaments/joint capsulses contribution to stability

A
  • Provide resistance against ground reactive force
  • Prevent unwanted movement
  • Support desired joint position
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8
Q

Neuromuscular activity contribution to stability

A
  • Types of muscular contraction
  • Agonist, antagonist dynamics
  • Joint proprioception
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9
Q

Bones are designed functionally for

A
  • Shock absorption
  • Distribution of external stresses
  • Muscle attachments
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10
Q

Osseous configuration of bone (examples)

A
  • Anterior lip of tibial plateau
  • Anterior medial aspect of calcaneus
  • Posterior cuboid
  • Lateral process of talus
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11
Q

Knee joint extension (stability)

A
  • Anterior lip of the medial facet of the tibia

- Prevents over-extension of the knee

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12
Q

Calcaneocuboid joint (stability)

A
  • Excessive pronation inhibited by the dorsal “overhang” of the calcaneus
  • This creates a close-packed position
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13
Q

Types of joints

A
  • Ball and socket
  • Condyloid
  • Saddle
  • Hinge
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14
Q

Ligament influence on stabilization

A
  • Orientation/angulation

- Joints passed

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15
Q

Muscle contribution to joint stabilization

A
  • Agonist or prime movers
  • Antagonists
  • Stabilizers
  • Orientation to joint
  • Pennation
  • Type of tendinous insertion
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16
Q

Muscular role in joint movement

A
  • Prime mover
  • Antagonist
  • Synergist
  • Stabilizer
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17
Q

Types of muscle contraction

A
  • Isometric

- Isotonic

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18
Q

Muscle architecture

A
  • Parallel
  • Pennate
  • Type of muscle fibers
  • Relation to joint axis
  • Shape of tendon
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19
Q

Proprioception (“sense of self”)

A
  • Conscious: Dorsal Columns

- Unconscious: Cerebellar

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20
Q

Mediators of proprioception

A
  • Muscle spindle monitors muscle length
  • Golgi tendon organ monitors muscle tension
  • Pacinian corpuscle monitors pressure
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21
Q

Two basic requisites for walking

A
  • Continued ground reactive forces

- Periodic movement in the direction of progression

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22
Q

Center of mass should remain

A
  • In the pelvis

- The body should NOT tip!!!

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23
Q

To keep the center of mass within the pelvis

A
  • It “hovers” at constant height and minimally changing velocity
  • Decreased the energy required to walk
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24
Q

Center of mass

A
  • The point where the distribution of mass is equal in all directions
  • It does not rely on gravitational pull
25
Center of gravity
- The point in a body where the forces of gravity vanish - This may depend on the vertical orientation of the body - The is the product of mass x gravity
26
Center of gravity is located
- 2 inches anterior to the second sacral vertebrae | - It follows vertical and horizontal displacement
27
Center of gravity in anatomical position
- Anterior to S2 vertebra - At ~ 56% of persons height - Shifts with body movements - Balance is dependent upon maintaining the COG above the feet - Body will compensate by bending and extending
28
Vertical displacement
- Up and down movement - Highest point: midstance - Lowest point: double support - Average displacement: ~ 5 cm
29
Horizontal displacement
- Side to side movement | - Lateral limit: midstance (~ 5 cm displacement)
30
The gait cycle phases
- Stance | - Swing
31
Stance phase composed of
- Contact - Midstance - Propulsion
32
Contact (stance phase)
- Foot/heel strike - Loading response ending with full forefoot load - Foot adapting to terrain and absorbing shock
33
Midstance
- Full forefoot load to heel off - Foot converting to rigid lever - Entire foot is on the ground
34
Propulsion (stance phase)
- Terminal stance - Heel off to toe off - Forward movement of the limb
35
Swing phase composed of
- Acceleration - Midswing - Deceleration
36
Loading response
- Foot becomes “unlocked” to become a mobile adaptor - Controlled flattening results in shock absorption - Limb is actively extending at the hip and knee - Ends with full forefoot load
37
Propulsion (stance phase) accounts for
- 33% of stance | - Pre-swing
38
Pre-swing (propulsion)
- Heel lift - Toe off - Foot off loaded
39
During propulsion
- Muscles working to “shorten” the limb to clear the ground - Hip and knee flexors - Dorsiflexion and inversion of foot and ankle
40
Swing phase in open kinetic chain
- Distal segment moves freely | - Divided into initial swing, mid swing, and late/terminal swing
41
Initial swing
- Limb is accelerating
42
Late swing
- Limb is decelerating | - Extending the limb for contact
43
Six elements of gait
- Pelvic rotation - Pelvic list - Knee flexion in stance phase - Ankle mechanisms - Foot mechanisms - Lateral displacement of body
44
Pelvic rotation
- Rotation about vertical axis - Transverse plane motion - Accomplished with flexion and extension of the hip - Rotation of ~4° on either side of axis - Increases with speed
45
Swing leg during pelvic rotation
- Rotates medially | - Rotation is 4° with double support
46
Goal of pelvic rotation
- Vertical adjustment | - The limbs are essentially lengthened without lowering the COM
47
Pelvic rotation occurs with
- Forward advancement of the swing limb | - Preparation for heel strike
48
Pelvic list
- Downward movement in the frontal plane | - Alternating hip movement
49
Motions in pelvic list
- Adduction in stance - Abduction in swing - ~ 5° angular displacement
50
During pelvic list
- There is a 5° dip on the swinging limb | - This reduces the height of the apex of the curve
51
The 5° dip on the swinging limb during pelvic list occurs with
- Adduction of the weight bearing limb | - Abduction of the swing limb
52
Knee flexion in stance phase
- Close to full extension - Flexes until the foot is flat on the ground (normally ~ 15) - Moves to extension with full weight bearing - Then… flexion with heel off - Elongates and shortens the limb
53
Combination of pelvic rotation, pelvic list, and knee flexion during stance
- Decrease vertical displacement of COM - Abrupt displacements still occur - Walking is still a series of arcs (not a smooth curve)
54
Foot and ankle mechanisms
- Two intersecting arcs of rotation - Hell contact - Heel rise - Together, smooth out the pathway
55
Heel contact
- Rotation of ankle about radius formed by heel
56
Heel rise
- Rotation of the forefoot
57
Lateral displacement of the body
- Side to side displacement - ~4-5 cm with each stride - Slight genu valgum keeps tibia vertical
58
Lateral displacement is slightly increased when
- Feet are further apart
59
Lateral displacement is slightly decreased when
- Decreased when feet are closer

Intro to Biomechanics (8 decks)

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