Chapter 11 - Muscular System Flashcards
How many individual muscles are contained in the muscular system?
About 700
What is the muscular system composed of?
The voluntarily controlled muscles of the body
What is function of muscles in the muscular system?
To produce movements of body parts
How do skeletal muscles produce movement?
By exerting force on tendons, which pull the bones or other structures (such as skin)
What is the origin?
The attachment of a muscle’s tendon to a stationary bone
What is the insertion?
The attachment of the muscle’s tendon to the moveable bone
When two bones articulate with each other, do they both move?
No, they usually do not move equally in response to a contraction.
One bone remains stationary and the other is pulled toward it.
Is the origin usually proximal or distal?
Is the insertion usually proximal or distal?
Origin - proximal
Insertion - distal
Does the insertion get pulled towards the origin or
Does the origin get pulled towards the insertion?
Insertion pulled towards origin
What is the belly (body)?
The fleshy portion of the muscle between the tendons
What are the actions of a muscle?
The main movements that occur when the muscle contracts
What is reverse muscle action? (RMA)
During specific movements of the body, the actions are reversed.
Therefore the positions of the origin and insertion of a specific muscle are switched.
Where is the belly of the muscle the extends the forearm located?
The triceps brachii, is located posterior to the humerus
What is a lever? What are the levers of the body?
A rigid structure that can move around a fixed point
Bones
What is the fulcrum? What serves as fulcrums in the body?
A fixed point that a lever moves around.
Joints.
What two different forces act on levers at two different points?
Effort - which causes movement
Load (or resistance) - which opposes movement
What is effort?
The force exerted by muscular contraction
What is the load (or resistance)?
The weight of the body part that is moved, or
Resistance that the body is trying to overcome
When does motion occur?
When the effort applied to the bone at the insertion exceeds the load
If you were to raise your forearm holding a book, what would be the fulcrum, the effort and the load?
Fulcrum - elbow
Effort - force of contraction of the biceps brachii
Load - weight of the forearm + weight of book
What is a mechanical advantage?
If the load is closer to the fulcrum and the effort farther from the fulcrum
A small effort is required to move a large load
What is a mechanical disadvantage?
If the load is further from the fulcrum and the effort closer to the fulcrum
A large effort is required to move a small load
What are the three types of levers?
- First class lever
- Second class lever
- Third class lever
What is a first class lever?
Fulcrum is between the effort and the load
Scissors and see-saws