Question

10. In the skeletal system...which structures act as levers and which as fulcrums? What is a lever? Name and define the two forces that act on a lever? What is required to achieve motion? 11. Briefly describe the difference between the different classification of levers. (I would draw something that helps you remember cach definition). Give an example of each. 12. Muscles are arranged for total coordination. Define the following terms and describe their function. Prime mover Agonist Antagonist Synergist Fixator

Answer 1

10. In the skeletal system, the bones act as levers while the joints act as fulcrums. A lever is a tool or a device which is in the shape of a rod which has a pivot support which enhances to lift a weight on one side by applying force on the other side. The two main forces acting on the lever are, the pivoting force from the lifting side and the force of depression at the pivot junction. An external angular force is required to aquire motion.

11. There are mainly three types of levers:

(a) Class 1 lever : In class 1 levers,the direction of motion of effort is opposite to the direction of motion of load. The fulcrum sits in between the effort arm and load arm. Examle : Teeter-totter

(b) Class 2 lever : In class 2 levers,the irection of motion of effort is same as that of direction of motion of load. The load sits between effort and fulcrum. Example : Crowbar

(c) Class 3 lever : In class 3 lever also,the direction of motion of effort is same as that of direction of motion of load.The difference is only that here, the effort arm sits in between load arm and fulcrum. Example : Stapler

12. (a) Prime mover : A prime mover muscle is the muscle which tranfers the force to move a bone. Example : biceps,when sqeezed. Triceps ,when squeezed.

(b) Agonist : Agonist is same as that of a Prime mover.No difference at all.Example: the above mentioned.

(c) Antagonist : Antagonist muscles are those typeof muscles which resists certain movements in the body.Example are :biceps,when tricepsare squeezed., triceps,when biceps are squeezed

(d) Synergist : Synergist muscles perform similar toprimemover or agonist muscles. But theyact on movable joints. They mostly work as a pair.Example : Chest muscle, shoulder muscle

(e) Fixator : Fixator is a kind of muscle which stabilises the origin of the primemover during a movement. Example : Deltoid muscle.