chapter 1 Flashcards
What branch of mechanics describes motions of the body
kinematics
The center of mass of the human body tends to move in what line
curvilinear
movement of the body can be described as which two ways
active or passive
What are the three planes of motion and how do they divide the body
Sagittal: Left and right sides
Frontal (coronal): anterior and posterior
Transverse (horizontal): superior and inferior
Osteokinematics describes what
motion of the bones relative to the three planes
The number of independent directions of movement at a joint is referred to as what?
Degrees of freedom
The sagittal plane allows what type(s) of joint movement(s)?
flexion and extension
Forward/backward bending
The frontal plane allows what type(s) of joint movement(s)?
ABduction and ADduction
Lateral flexion
Ulnar and radial deviation
eversion and inversion
The transverse plane allows what type(s) of joint movement(s)?
Internal and External rotation
Axial Rotation
What part of the joint has zero body motion?
axis of rotation
Accessory motions are defined as
slight passive translations that occur in most joints
What are the two perspectives that movement can be described as?
Proximal segment can rotate against a fixed distal segment (closed kinetic chain)
Distal segment can rotate against a fixed proximal segment (open kinetic chain)
Arthrokinematics describes what
motion that occurs between the articular surfaces of joints
What are the three fundamental movements that can exist between joint surfaces?
Roll, slide, and spin
Describe Roll-and-slide movement
rolling of its articular surface against another bone’s articular surface and coupled with the sliding of articular surface
describe the spin movement
spinning of its articular surface against the articular surface of another bone
Describe the convex-on-concave movement
convex segment rolls and slides in opposite directions
Describe the concave-on-convex movement
concave segment rolls and slides in similar directions
The position of maximal congruency is referred to as:
the joint’s close-packed positions
Accessory motions are _______ in a joint’s close-packed position?
minimal
Open(loose)-packed positions are considered to be
all positions other than close-packed
Accessory motions are _______ in open-packed position
maximal
Kinetics describes what branch of mechanics
the effect of forces on the body
When is the force zero
when the acceleration of the mass is zero
What forces are most frequently applied to the musculoskeletal system?
tension, compression, bending, shear, torsion, combo loading
the stress/strain curve shows what?
the amount of force required to deform an excised tissue
Viscoelasticity
factor of time, causing the stress/strain curve to change
creep
long, constant stress
i.e. your vertebral discs over the course of day, hence why you are shorter in the evening.
Forces produced from structures within the body are referred to as:
internal forces
Active internal forces are produced by what?
muscles under volitional control
passive internal forces are produced by what?
gravity, or tension in stretched connective tissues
What forces occur outside of the body?
External forces
Line-of-force or line-of-gravity
direction of a muscle force and the direction of gravity
angle of insertion
angle formed between the tendon of a muscle and the long axis of the bone to which it inserts
Gravity acts on what part of the body segment
center of mass
Joint reaction force
force through the center of the joint, produced between surfaces of a joint
static linear equilibrium
where no movement occurs due to equal forces
forces that act at a distance from the axis of rotation produce what?
a potential rotation of the joint
moment arm
distance the force is acting, that causes the torque
When internal moment equals the external moment, what happens?
no motion or rotation
aka static rotary equilibrium
What are the types of muscle activation?
concentric, eccentric, and isometric
concentric contraction refers to what?
the shortening of the muscle fibers
eccentric contraction refers to what?
the lengthening of muscle fibers
isometric contraction refers to what?
the fiber lengths do not change
biceps vs. triceps is termed as what?
agonist vs. antagonist
gluteus max + hamstrings is termed what?
synergists
hip flexors and low back extensor muscles is termed what?
force-couple
Force-coupling
what two or more muscles simultaneously produce forces in different linear directions, although the resulting torque act in same rotary direction (ie turning wheel with two hands)
how many musculoskeletal levers are there?
three
1st class lever
axis of rotation is between opposing forces
2nd class lever
axis of rotation is located at one end of the bone, and the internal force (muscle) has greater leverage than the external force
3rd class lever
axis of rotation is at one of the bone, and the external force exceeds the internal force
what lever is most common
third class
what is mechanical advantage (MA)
a ratio of the internal moment arm to the external moment arm (external force to internal force)
why must third class levers always have MA<1
The muscle force must produce a force that is much greater than the opposing external force
