biomechanics of movement

Question 1

what are the 4 basic components to a lever system?

Answer 1

• lever arm (rigid bar)
• fulcrum (point of rotation)
• resistance
• applied force

Question 2

what serves as the lever arm in vertebrates?

Answer 2

skeletal components (bones)

Question 3

what serves as the fulcrum in vertebrates?

Answer 3

joint, or at the ground surface

Question 4

what serves as the resistance in vertebrates?

Answer 4

• gravity, inertia

- placement of body parts against a relatively immovable object

Question 5

what serves as the applied force in vertebrates?

Answer 5

muscle contraction

Question 6

where is the fulcrum positioned in a first class lever system/

Answer 6

between the force and the resistance

-e.g. cubital joint extension by triceps brachii

Question 7

how is a second class lever system positioned?

Answer 7

the resistance is positioned between the fulcrum and the force
-e.g. the tarsal joint extension by gastrocnemius

Question 8

what class of lever system is it if the limb is free to swing?

Answer 8

first class

Question 9

what class of lever system is it if the limb is planted on the ground?

Answer 9

second class

Question 10

how is a third class lever system positioned?

Answer 10

the force is between the resistance and the fulcrum

-e.g. cubital joint flexion by biceps brachii

Question 11

what class of lever describes the pull of the gluteal mm on the greater trochanter when the femur is free to swing caudally?

Answer 11

first class

Question 12

extension of the carpal joint(s) by the extensor carpi radialis m. is an example of which class of lever?

Answer 12

third class

Question 13

the appied force necessary to cause (or prevent) movement depends on the ____ distance of the forces from the fulcrum and is subject to change throughout the range motion.

Answer 13

perpendicular

Question 14

T/F: All movement is produced by lever systems.

Answer 14

false

Question 15

there will be increased tension but no movement when resistance force ____ the applied force.

Answer 15

resistance force EQUALS the applied force.

Question 16

a muscle that produces a certain referenced effect or movement

Answer 16

agonist

Question 17

a muscle capable of actively opposing a movement

Answer 17

antagonist

Question 18

a muscle that may neither facilitate nor directly oppose the movement but may modify the action of the agonist, perhaps eliminating an unwanted side effect?

Answer 18

synergist

Question 19

a muscle that is employed to stabilize a joint rather than promote its movement

Answer 19

fixator

Question 20

contraction of what muscle would prevent extension of the humeral joint during flexion of the cubital joint by the biceps brachii m.?

Answer 20

deltoideus m.

Question 21

in what phase of the stride is the limb in contract with the ground?

Answer 21

stance phase

Question 22

in what portion of the stride is the limb not in contact with the ground?

Answer 22

swing phase