Chapter 10 Flashcards
The muscular system
Muscle tissue – all contractile tissues
*Skeletal, cardiac, smooth muscle
- Focus on skeletal muscle
- How muscles interact to -> movement
- Criteria for naming muscles
- Principles of leverage
Actions and interactions of skeletal muscle
Muscles can only pull; never push
What one muscle group “does”, another “undoes”
- Agonist: primary mover
- Antagonist: opposes or reverses particular movement
agonist
primary mover
antagonist
opposes or reverses particular movement
skeletal muscles: functional groups
- synergist
- fixator
Synergist
helps prime movers
*adds extra force to same movement
*reduces undesirable or unnecessary movement
fixator
- Synergist that immobilizes bone or muscle’s origin (rotator cuff and G-H joint)
- Gives prime mover stable base on which to act (ex scap and G-H joint)
anterior side does flexion
true
Posterior side does extension
T
Lateral to joint does abduction
T
Medial to joint does adduction
T
Naming skeletal muscles
Muscle location—bone or body region with which muscle associated
Muscle shape—e.g., deltoid muscle (deltoid = triangle)
Naming skeletal muscles
- Muscle size:
- maximus (largest)
- minimus (smallest)
- longus (long)
- Direction of muscle fibers or fascicles
- rectus (fibers run straight),
- transversus (fibers run at right angles),
- oblique (fibers run at angles to imaginary defined axis)
Naming skeletal muscles
-Number of origins—e.g., biceps (2 origins) and triceps (3 origins)
- Location of attachments—named according to point of origin and insertion (origin named first)
- sternocleidomastoid
- Muscle action—named for action they produce, e.g., flexor or extensor
- Several criteria can be combined, e.g., extensor carpi radialis longus
T tubules are an extension of the
sarcolemma
T-tubules are extensions of the cell membrane (sarcolemma) that associate with the ends (terminal cisternae) of the sarcoplasmic reticulum
The force exerted by a contracting muscle is _______.
muscle tension
Which activity would be most dependent upon creatine?
diving
Creatine phosphate is a molecule that can store energy in its phosphate bonds. … This acts as an energy reserve that can be used to quickly create more ATP. When the muscle starts to contract and needs energy, creatine phosphate transfers its phosphate back to ADP to form ATP and creatine.
Muscle mechanics: the importance of fascicle arrangement and leverage
- additional factors contributing to muscle force and speed
- fascicle arrangement
- lever systems
How skeletal muscles produce movement: fascicle arrangement
-Fascicle arrangement affects a muscles power and range of motion
- 5 patterns of fascicle arrangement:
- parallel
- fusiform
- circular
- triangular
- pennate
- longer fibers produce a greater range of motion
- power of a muscle depends on its cross-sectional area
Arrangement of fascicles: CIRCULAR
Fascicles arranged in concentric rings (e.g., orbicularis oris, orbicularis oculi)
Arrangement of fascicles:
CONVERGENT
Broad origin; fascicles converge toward single tendon insertion (e.g., pectoralis major)
Arrangement of fascicles: PARALLEL
Fascicles parallel to long axis of straplike muscle (e.g., sartorius)
Arrangement of fascicles:
FUSIFORM
Spindle-shaped muscles with parallel fibers (e.g., biceps brachii)
Arrangement of fascicles:
PENNATE
-Short fascicles attach obliquely to central tendon running length of muscle (e.g., rectus femoris)
- Three forms:
- Unipennate – fascicles attach only to one side of tendon (e.g., extensor digitorum longus)
- Bipennate – fascicles insert from opposite sides of tendon (e.g., rectus femoris)
- Multipennate –appears as feathers inserting into one tendon (e.g., deltoid)
Unipennate
arrangement of fascicles: pennate (1)
fascicles attach only to one side of tendon (e.g., extensor digitorum longus)
Bipennate
arrangement of fascicles: pennate (2)
fascicles insert from opposite sides of tendon (e.g., rectus femoris)
Multipennate
arrangement of fascicles: pennate (3)
appears as feathers inserting into one tendon (e.g., deltoid)
Muscle mechanics: Lever systems
-Levers allow given effort to move heavier load; move load farther or faster
- Components of lever system:
- Lever—rigid bar (bone) that moves on a fixed point called fulcrum (joint)
- Effort—force (supplied by muscle contraction) applied to lever to move resistance (load)
- Load—resistance (bone + tissues + any added weight) moved by the effort
Lever
rigid bar (bone) that moves on a fixed point called fulcrum (joint)
Effort
force (supplied by muscle contraction) applied to lever to move resistance (load)
Load
resistance (bone + tissues + any added weight) moved by the effort