Muscular System Part 5 - important key notes for exams PDF

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important key notes for exams...

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Muscular System Part 5 Chapter 10

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Origin = NO movement Insertion = movement ○ Ex: biceps brachii muscle - origins (shoulder region), insertion (radius)

Muscle Movements -Functional Groups: 1. Prime mover/Agonist ○ Ex: pectoralis major – total arm flexion* ○ Ex: biceps brachii – forearm flexion* 2. Antagonists - (muscles that oppose agonist movement); **can also be considered prime movers* ○ Ex: latissimus dorsi – antagonist to pectoralis major ○ Ex: triceps brachii – antagonist to biceps brachii 3. Synergists – assisting movements/supportive; **also stabilize joints (undesirable movements)** ○ Ex: finger flexors ○ Subcategory: "Fixators" - a synergist that specifically immobilizes a bone ■ Ex: scapula ■ Ex: muscles of posture 4.

7 Criteria for Naming Skeletal Muscles 1. Location of muscle – ○ Ex: temporalis, intercostals, rectus, abdominis 2. Shape of muscle – ○ Ex: Deltoid = "delta" shape ○ Trapezius = trapezoid shape 3. Size of muscle - maximus, minimus, longus, brevis, gluteus maximus

4. Direction of fibers - Rectus, transversus (horizontal), oblique ○ Ex: rectus femoris 5. Number of origins – name lists number of origins*** ○ Ex: BIceps brachii = 2 origins ○ Ex: TRIceps brachii = 3 origins ○ QUADriceps = 4 origins 6. Location of origins and insertions ○ Ex: sternocleidomastoid: insertion = mastoid process; origins = sternum & clavicle 7. Action of muscle – flexor, adductor, extensor ○ Ex: "adductor longus"

Fascicle Arrangement **determine muscle's force and shape*** -Patterns of Fascicle Arrangement: 1. Circular – muscles that surround body openings ("sphincters") 1. Ex: mouth - "orbicularis oris" 2. *** origins around outside of circle insertions on inside of circle*** 2. Convergent – fascicles converge toward insertion; triangular fan shaped muscles 1. Ex: pectoralis major deltoid 3. Parallel – fascicles & fibers run parallel to muscle axis 1. Ex: strap or spindle shape muscles 2. Ex: biceps brachii (spindle shape) 4. Pennate – fascicles are short & fan shaped converging to central tendon of muscle 1. Unipennate: fascicles insert into one side of tendon ■ Ex: extensor digitorum 2. Bipennate: fascicles into both sides of muscle's central tendon (feather) ■ Ex: rectus femoris 3. Multipennate: fascicles arranged around small tendons inserting into one larger central tendon (many feathers) ■ Ex: deltoid ***Arrangement of fascicles determines its range of motion & power*** ***Muscles with parallel fascicles shorten most, but these are NOT most powerful***

***Muscle's power determined by the number of fibers in fascicles/muscle***

Muscles & Levers ●

Lever (bone) – rigid bar moves on a fulcrum (a.k.a. fixed point) (joints); "load" bone itself ○ Power Lever: strong; load is near fulcrum (NOT much movement) ○ Speed Lever: weak; load is far from fulcrum; fast (MUCH movement)

-Class of Levers1. 1st Class: ***mechanical*** 2. 2nd class: ***advantage; slower; more stable*** 3. 3rd Class: **MOST skeletal muscles of body behave as 3rd class***; mechanical disadvantage; not strong but very fast; ***muscles tend to be thicker around these levers*** ○ Ex: hinge joints...