Chapter 10 Flashcards
How do muscles move body parts?
- when they contract they shorten
2. when they shorten they pull on bone
Can muscles push?
no, only pull forcefully
When muscles work in opposing pairs what is they called? give an example
antagonistic pairs
eg. biceps (flexion) & triceps (extension)
Muscles usually stretch across the joint. Where do they attach?
- origin - end of muscle that does not move
2. insertion - end of muscle that does move
What direction does the insertion move?
insertion moves toward the origin when muscle shortens and pulls bone with it
What are the 5 functional groups?
- prime movers
- antagonists
- reversal of roles
- synergists
- fixators
What are the prime movers?
they provide the major force for producing a specific movement
What are the antagonists?
oppose or reverse a particular movement
What is reversal of roles?
when the prime movers and antagonists can reverse roles
What are synergists? and what is their purpose
they add force to a movement: assist the prime mover
they reduce undesirable or unnecessary movement
What are fixators? and what is their purpose
they are synergists that immobilize a bone or muscle’s origin
they stabilize a joint - maintaining upright posture
What are the 7 criteria used for naming a muscle? and give example
- location - brachialis
- shape - deltoid (triangle)
- relative size - gluteus maximus
- direction of fiber - external oblique
- number of origins - triceps
- location of attachments - sternocleidomastoid
- action - adductor
What is the muscle dependent on in order to carry out a function?
- position of the muscle
- arrangement of fascicles
- lever systems
What does a muscle that crosses on the anterior side produce?
flexion
What does a muscle that crosses on the posterior side produce?
extension
What does a muscle that crosses on the lateral side produce?
abduction
What does a muscle that crosses on the medial side produce?
adduction
Where are circular fasicles found?
around body openings (ie. mouth)
Where are convergent fasicles found?
converge toward a single narrow tendon (ie. pectoralis major)
Where are parallel fasicles found?
parallel to the long axis of a strap like muscle (ie. sartorius)
Where is fusiform fasicles found?
spindle-shapes muscles with parallel fibers (ie. biceps)
Where are pennate fasicles found?
these are short fasicles that attach obliquely to a central tendon running the length of the muscle
Name the three types of pennate fasicles and describe.
- unipennate - fascicles insert into one side only of tendon
- bipennate - fascicles insert from both sides
- multipennate - like many feathers side by side (eg. deltoid)
What are the 4 components of a lever system?
- lever
- fulcrum
- effort
- load
What is the lever?
rigid bone that moves on a fixed point or fulcrum
What is the fulcrum?
the pivot point (joint, articulation)
What is the effort?
force (supplied by muscle contraction) applied to a lever to move a resistance
What is the load?
resistance moved by the effort (bones & tissues plus any added weight)
What are the 3 lever systems?
- first class
- second class
- third class
What is a first class lever? and give example
fulcrum (joint) between load and effort
(ie. scissors
What is a second class lever? and give example
load between fulcrum (joint) and effort
ie. wheel barrow, standing on tip toe
What is a third class lever? and give example
effort applied between fulcrum and load
ie. tweezers, flexing an arm
What is the lever system called that works with a mechanical advantage? and why are they called this?
power levers
because they move a big load with a small effort but they are slow (ie. jacking up a car)
What are other levers called that work with a mechanical disadvantage? and why?
speed levers
they are faster but take move effort to move a small load (ie. move a pile of dirt with a shovel)
Where do muscles of facial expression insert into?
into the skin
