Chapter 11 The Muscular System Flashcards
What is the relationship between bones and muscles in producing body movements?
Bones and muscles work together through muscle attachment sites, lever systems, fascicle arrangement, and coordination within muscle groups.
Define lever and fulcrum in the context of the muscular system.
A lever is a rigid structure that moves around a fixed point called a fulcrum.
List the three types of levers based on the locations of fulcrum, effort, and load.
- First-class levers
- Second-class levers
- Third-class levers
How does the arrangement of fascicles affect muscle contraction?
Fascicle arrangement affects a muscle’s power and range of motion; longer fibers increase range of motion, while greater cross-sectional area increases power.
What are the roles of prime movers, antagonists, synergists, and fixators in muscle coordination?
- Prime mover: Contracts to create movement
- Antagonist: Stretches and yields to prime mover
- Synergist: Stabilizes intermediate joints
- Fixator: Stabilizes the origin of the prime mover
What are the seven features used in naming skeletal muscles?
- Location
- Size
- Shape
- Direction of fibers
- Number of origins
- Location of attachments
- Action
Fill in the blank: The __________ of a muscle is usually proximal, and the __________ is usually distal.
origin; insertion
True or False: Most muscles cover the body part they move.
False
What is the action of a muscle?
The main movements that occur when the muscle contracts.
What is reverse muscle action (RMA)?
When the actions of a muscle are reversed, switching the positions of the origin and insertion during specific movements.
Describe the arrangement of muscle fibers in parallel muscles.
Muscle fibers run parallel to the length of the muscle and end in flat tendons on both sides.
What characterizes fusiform muscles?
Muscle fibers run almost parallel and narrow toward the ends, being wider in the middle.
What is a circular muscle?
Muscle fibers arranged in circles that form sphincter muscles, surrounding and closing an opening.
What is the benefit of pennate muscle arrangement?
Greater power due to a large number of short-fibered fascicles.
What is the mechanical advantage in lever systems?
Occurs when the load is closer to the fulcrum than the effort, requiring less effort to move a large load.
In a third-class lever, where is the effort located?
Between the fulcrum and the load.
What happens when a prime mover and its antagonist contract simultaneously with equal force?
There will be no movement.
What is the primary function of fixators in muscle coordination?
To stabilize the origin of the prime mover for more efficient action.
What is the role of the deltoid muscle in arm abduction?
Serves as the prime mover and pulls on the humerus to abduct the arm
What are fixators in muscle movement?
Muscles that hold a bone steady during movement
What is a compartment in the context of skeletal muscles?
A group of skeletal muscles, their associated blood vessels, and nerves with a common function
How are skeletal muscles typically named?
Based on distinctive features like size, shape, action, number of origins, and location
What does the term ‘rectus’ indicate in muscle naming?
Muscle is parallel to the midline
What does ‘maximus’ indicate in muscle naming?
Largest muscle
