Download Describing Motion

Physics 160 Biomechanics
Describing Human Motion
Forms of motion:
Linear motion: motion along a line
• Rectilinear motion: (along a straight
line)
• Curvilinear motion: (along a curved
line)
Forms of motion:
Angular motion: rotation around an axis
Forms of motion:
General motion: a combination of linear
and angular motion (includes most
human motion)
Forms of Movements
2. Angular
• rotation
3. General
1. Linear
• translation
• all points on the body
move the same distance
in the same direction in
the same amount of time
Dimensions of Movement
• 0 Dimensions - point.
• 1 Dimension - line.
• 2 Dimensions - plane.
• 3 Dimensions - cube, sphere, etc.
• 4 Dimensions - 3 Dimensions + time.
Movement occurs in all 4 dimensions (time and
space).
0D particle
1D Line
3D- volume
2D flat
surface
Anatomical Concepts and
Terminology
Movements of the body are defined in
respect with the neutral anatomical
position:
Legs straight and feet pointed
forward
Arms at the sides of the body and
palms facing forward
Sagittal Plane
• sagittal plane
- divides body into left and
right
- in which forward and
backward movements
occur
- flexion, extension and
hyperextension
What movements occur in the
sagittal plane?
Flexion
Extension
Dorsiflexion
Hyperextension
Plantar flexion
Frontal Plane
• frontal plane
- divides body into front and
back
- in which lateral movements
occur
- adduction and abduction
- lateral flexion
- elevation and depression
- ulnar and radial deviation
- eversion and inversion
What movements occur in the
frontal plane?
Radial
deviation
Abduction
Adduction
Elevation
Lateral flexion
Depression
Eversion
Inversion
Ulnar
deviation
Transverse Plane
• transverse plane
-divides body into top and
bottom
- in which rotational
movements occur
- medial and lateral rotation
- pronation and supination
- horizontal abduction and
adduction
What movements occur in the
transverse plane?
Horizontal
adduction
Pronation Supination
Medial
rotation
Lateral
rotation
Horizontal
abduction
Reference Axes
• mediolateral axis around which rotations
in the sagittal plane
occur
• anteroposterior axis around which rotations
in the sagittal plane
occur
• longitudinal axis around which rotational
movements occur
Cardinal Axes of the Body
• X-Axis (Mediolateral Axis)
– perpendicular to Sagittal
plane
• Y-Axis (Longitudinal Axis)
– perpendicular to Transverse
plane
• Z-Axis (AnteroposteriorAxis)
– perpendicular to Frontal
plane
Movement, both whole body and
segmental, takes place in the
cardinal planes and around the
cardinal axes.
Planes and Axes
Swinging your leg
front and back takes
place in the sagittal
plane about the
mediolateral axis
X-Axis
• Passes from side to side.
• Rotation in the sagittal plane takes place
around the x-axis.
Y-Axis
• Passes from top to bottom.
• Rotation in the transverse plane takes place
around the y-axis.
Z-Axis
• Passes from front to back.
• Rotation in the frontal plane takes place
around the z-axis.
Kirtley, C. (2002)
Plane of Motion and Muscle
Function
• Plane of motion provides information about
actions of muscles:
– Within-plane muscles act as prime movers
• Agonist : Speeds up a movement
(concentric)
• Antagonist: Slows down a movement
(eccentric)
• Can also act as stabilizers (isometric)
– Out-of-plane muscles act primarily as
stabilizers (or neutralizers)
• Prevent unwanted motion
Joint Planes of Action
Table 3.1
Degrees of Freedom
• The number of axes joint (or movement) can
rotate around
– Elbow joint has 1 DF
– Knee has 2 DF
– Shoulder has 3 DF
Anatomical Concepts and Terminology
Posterior
Aspect
Right
Lateral
Aspect
Left Lateral
Aspect
Anterior
Aspect
Superior Aspect
Inferior Aspect
Anatomical Concepts and Terminology
Lateral: away from the center of the trunk of the body, in
the coronal plane
versus
Medial: toward the center of the trunk of the body, in the
coronal plane
Laterally
Medially
Medial aspect of the foot
Lateral aspect of the foot
Directional terms:
• superficial: toward the surface of the
body
• deep: inside the body away from the
surface
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
•Proximal:
•Closer to the trunk
•Distal:
•Further from the trunk
Anatomical Concepts and Terminology
Dorsal:
the upper side of an organ
Versus
Ventral:
the lowest side of an organ
Dorsal Aspect
Plantar Aspect
The dorsal side of the foot is the upper aspect and the
plantar is the lowest aspect
Pronation and Supination
• Pronation and supination of the feet
are not the same as inversion
and eversion
• Pronation of the foot
– Dorsiflexion at the ankle
• Eversion in the tarsals
– Abduction of the forefoot
• Supination of the foot
– Plantarflexion at the ankle
– Inversion in the tarsals
– Adduction of the forefoot
Spatial Reference Systems
• useful for standardizing
descriptions of human motion
• most commonly used is the
Cartesian coordinate system
• human body joint centers are
labeled with numerical x, y and z
coordinates
Spatial Reference Systems
Y
(x,y) = (3,7)
(0,0)
X
Cartesian coordinates of the hip
Spatial Reference Systems
y
x=y=+
x=+
y=+
x
(0,0)
x=y=-
x=+
y=-
Coordinates can be both positive and
negative.
Anthropometry
Study of the physical
dimensions of the human body
Applications:
- Design of Work Spaces
(e.g. aircraft cockpits)
- Design of Specialized Suits
(e.g. pressure or space
suits)
In Biomedical Engineering:
- Design of Implants
Segment Length Anthropometry
Stature
173.0 cm
Hand (wrist to tip of middle finger)
18.7 cm
Forearm (elbow to wrist)
25.3 cm
Upper arm (shoulder to elbow)
32.2 cm
Head, neck & trunk (hip to top of head)
81.3 cm
Hip to shoulder joint
50.0 cm
L5/S1 to hip
9.9 cm
Thigh (hip to knee)
42.4 cm
Lower leg (knee to ankle)
42.6 cm
Foot (heel to toe)
26.3 cm
Ankle height from floor
6.7 cm
Segment Mass Anthropometry
Hand
0.4 kg
Forearm
1.2 kg
Upper arm
2.1 kg
Head, neck and trunk
43.4 kg
Head, neck and trunk above L5/S1b
33.5 kg
Upper leg
7.4 kg
Lower leg
3.4 kg
Foot
1.0 kg
Total body weight
74.4 kg
Segment Center of Mass
Hand (wrist to hand CM)
9.2 cm
Forearm (elbow to forearm CM)
10.9 cm
Upper arm (shoulder upper arm CM)
14.0 cm
Head, neck & trunk (hip to HNT CM)
32.5 cm
HNT above L5/S1 (HNT/L5)
(L5/S1 to HNT/L5 CM)
26.6 cm
Thigh (hip to upper leg CM)
18.4 cm
Lower leg (knee to lower leg CM)
18.4 cm
Foot (heel to foot CM)
11.3 cm
Uses of Anthropometric Data
• Ego design: your own body dimensions are used as a
guideline;
• Average design: the body dimensions of the average
person are the guideline;
• Design for P5: the body dimensions of the smallest
person are the guideline;
• Design for P95: the body dimensions of the largest
person are the guideline;
• Design for P5-P95: the body dimensions of the
smallest and largest person are the guideline. This
type is used most commonly and means that
excluding 10% of the population is acceptable.
• Design for All: This implies a continuous effort
throughout the design process to exclude as few
persons as possible.