Muscles system pt 1 Flashcards
Muscular system
Muscle tissue: all contractile tissue (skeletal, cardiac, smooth muscle)
- focus on skeletal muscle (how muscles interact to movement)
Actions + interactions of skeletal muscles (antagonist/agonist)
- muscles can only pull NEVER push
- what one muscle group does, another undoes
- agonist: primary mover
- antagonist: opposes/reverses particular movement
Functional groups (2)
- Synergist: helps prime movers
- adds extra force to same movement
- reduces undesirable/unnecessary movement - Fixator: synergist that immobilizes bone/muscle’s origin (rotator cuff + GH joint)
- gives prime mover stable base on which to act (scapula + GH joint)
What does anterior/posterior/lateral/medial do?
- Anterior side does flexion
- posterior side does extension
- lateral to joint does abduction
- medial to joint does adduction
Naming skeletal muscles (7 factors)
- Muscle location: bone/body region with which muscle associated
- Muscle shape: deltoid muscle (deltoid = triangle)
- Muscle size: maximus (largest), minimus (smallest), longus (long)
- Direction of muscle fibers/fascicles: rectus (fibers run straight)
- transversus (fibers run at right angles)
- oblique (fibers run at angles to imaginary defined axis) - Number of origins: biceps (2), triceps (3)
- Location of attachments: named according to point of origin and insertion (origin names first) –> sternocleidomastoid
- Muscle action: named for action they produce (flexor/extensor)
Muscle mechanic: Fascicle arrangement + leverage
- additional factors contirbuting to muscle force + speed
- fascicle arrangement: affects muscle’s power + ROM
- 5 patterns: parallel, fusiform, circular, triangular, pennate
- longest fibers produce greater ROM
- power of a muscle depends on cross sectional area - lever systems: allow given effort to move heavier load; more load farther/faster (lever, effort, load)
Arrangement of fascicles
- Circular: fascicles arranged in concentric rings (eyes)
- Convergent: broad origin, fascicles converge toward single tendon insertion (pectoralis major)
- Parallel: fascicles parallel to long axis of straplike muscle (sartorius)
- Fusiform: spindle-shaped muscles with parallel fibers (biceps brachii)
- Pennate: short fascicles attach obliquely to central tendon running length of muscle (rectus femoris)
- 3 forms
- unipennate: fascicles attach only to one side of tendon (extensor digitorum longus)
- bipennate: fascicles insert from opposite sides of tendon (rectus femoris)
- multipennate: appears as feathers inserting into one tendon (deltoid)
Lever system (3) + advantage/disadvantage
- 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)
Mechanical advatange: If the distance from the effort to the fulcrum is greater than the distance from the load to the fulcrum (small effort can move large load)
Mechanical disadvantage: the effort arm (distance from the fulcrum to the effort) is shorter than the resistance arm (distance from the fulcrum to the load) (load moved rapidly over large distance; wide ROM)
3 classifications of lever
- 3 types of levers based on positions of fulcrum and effort + load
- First class levers: fulcrum is bw effort and load (seesaws)
- Second class levers: load bw fulcrum and effort (wheelbarrow)
- Third class levers: effort bw fulcrum + load (forceps)
Major skeletal muscles
- more than 600 in body, grouped by function + location
- info on each muscle depends on shape, location relative to other muscles, origin/insertion - usually joint bw origin and insertion,
- actions insertions moves toward origin
- innervation - name of major nerve that supplies muscle
