CH2 musculoskeletal system Flashcards
anatomy definition
the study of components that make up the musculoskeletal machine
biomechanics definition
the mechanics through which the musculoskeletal components interact to create movement
how do muscles function
by pulling against bones that rotate about joints and transmit force through the skin to the environment
can muscles pull or push or both
only pull
what is part of the axial skeleton
cranium, vertebral column, ribs, sternum
what is part of the appendicular skeleton
shoulder girdle,
left and right humerus,
radius and ulna,
carpal, metacarpals, phalanges,
pelvic girdle
left and right femur
patella
tibia, fibula
tarsals, metatarsals & phalanges
what are the types of joints and what mvt do they allow
fibrous joints: no mvt
cartilagenous joints: allow limited mvt
synovial joints: allow considerable mvt
what is the skeletal musculature
a sys of m. enables the skeleton to move
define origin and insertion and what def do we not consider
origin: proximal attachment (not more stationnary)
insertion: distal attachment (not more mobile)
definition agonist and antagonist and synergist
agonist: the muscle most directly involved in bringing about a mvt (prime mover)
antagonist: a muscle that can slow down or stop the movement
synergist: a muscle that assists indirectly in a movement
t/f all muscles of the body act thru levers
false, many m. do not act thru levers
body mvt directly involved in sport and exercise primarily act thru what kind of levers
bony levers
def lever
rigid or semirigid body that, when subjected to a force whose line of action does not pass thru its pivot point, exerts force on any object impeding its tendency to rotate
def torque
rotatory force (moment), is the magnitude of a force times the length of its moment arm. Degree to which a force tends to rotate an object about a specified fulcrum
def mechanical advantage and what does it quantify
the ratio of the moment arm through which an applied force acts to that thru which a resistive force acts
it quantifies how certain orientations affect force and velocity
what happens if MA is over 1.0
allows Fa<Fr to produce an equal amount of torque
is an advantage
favors high strength and low velocity
what happens if MA is under 1.0
allows Fa>Fr to produce an equal amount of torque
is an disadvantage
favors low strength and high velocity
describe a first class lever
Elbow extension against resistance
disadvantage MA<1.0
during isometric exertion or constant speed joint rotation
because Mm<Mr, Fm>Fr
describe a 2nd class lever
plantarflexion against resistance
advantage MA>1.0
when the body is stationary or moving upward at a constant velocity bc Mm>Mr, Fm<Fr
advantage bs a small muscular force is required to move a person’s body weight
describe a 3rd class lever
elbow flexion against resistance
disadvantage MA<1.0
when the arm is stationary or moving upward at a constant velocity because Mm<Mr, Fm>Fr
disadvantage bc a larger muscular force is required to move the resistance
how does the patella affect the MA of the quadriceps
it increases the MA of the quads by maintaining the quad tendon’s distance from the knee’s axis of rotation
relationship btw moment arm and mechanical advantage
the moment arm varies thru the joint’s ROM. when the M is shorter, there is less MA
as a weight is lifter, the M thru which the weight acts, & thus the resistive torque changes with the horizontal distance from the weight to the elbow
based on the MA equation what do most of the skeletal muscles operate at
considerable mechanical disadvantage
what is the primary lever orientation in the human musculoskeletal sys
3rd class 95%
humans are more built for strength or speed
built more for speed than strength
during sports or activities forces in the muscles and tendons are lower or higher than those exerted by the hands or feet on external objects or the ground
much higher
is it more important to understand the principle of Ma or classifying the lever
MA is more important than lever classification
tension insertion farther from the joint center
results in the ability to lift heavier weight
results in loss of max speed and reduces the muscle’S force capability during faster movement.
what occurs with a larger moment arm and torque
larger moment arm and thus greater torque for a given muscle force, but less rotation per unit of muscle contraction and thus slower movement speed
diff btw closer tendon insertion and further
closer: faster and weaker
further: stronger and slower
in what plane is the
standing barbell curl
sagittal
what plane is the lat dumbbell raise
coronal
what plane is the dumbbell fly
transverse