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What are lever systems?
bone-muscle relationship
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What is a fulcrum?
a fixed point at which a lever moves (ex. joint)
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What are rigid bars?
levers
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What do the joints and bones act as?
- joints - fulcrum
- bones - levers (rigid bars)
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What is a mechanical advantage?
not much effort is needed
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What is a mechanical disadvantage?
much effort is needed
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What does the distance of the load and effort from the fulcrum determine?
if there is mechanical advantage or mechanical disadvantage
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What is a first class lever?
- load-fulcrum-effort (ex. scissors)
- - raises your head off your chest
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What is a second-class lever?
- fulcrum-load-effort (ex. wheelbarrow)
- - stand on tip toe's
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What is third-class lever?
- load-effort-fulcrum (ex. tweezers or forceps)
- - flexing the forearm by the biceps rachii muscle
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What influences the muscles function?
fascicles that are arranged in different patterns (can be seen with the naked eye)
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What are the 4 arrangement of fascicles in muscles?
- 1. Parallel (ex. sartorius/biceps brachii/sternocleidomastoid)
- - fascicle axis is parallel to muscle with belly flanked by tendons
- - may be strap like or fusiform
- 2. Convergent (ex. pectoralis major)
- - converge at one tendon
- - resembles a triangle or fan-shaped
- - muscle fibers extend the length of the muscle from origin to insertion
- 3. Pennate-fasicles arranged along length of a tendon with the structure resembling a feather
- *multipennate (arranged side by side & end up connecting to 1 tendon, one of the strongest types of muscle)-deltoid
- *bipennate (fascicles are on both sides with tendon running down the middle)-rectus femoris/bicep femoris/
- *unipennate (fascicles on one side only)-excensor digitorum longus
- 4. Circular (orbicularis oris)
- - fascicles are arranged in concentric rings found at the opening of an organ, may be called sphincter or orbicularis
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What may be called sphincter or orbicularis?
circular
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What is an agonist?
prime mover that produces the movement
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What is antagonist?
- performs opposite action as agonist, but remains relaxed or stretched while agonist is contracting.
- ex..
- bicep - agonist
- triceps -antagonist
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What is a synergest?
muscle that works with an agonist to stabilize a joint or reduce unnecessary action at a particular joint.
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What are fixators?
hold a bone in place to provide a stable base for an agonist
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What do all muscles develop from?
mesoderm germ layer which folds into sections called myotomes and somitomeres.
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What are the 4 major groups of the mesoderm germ layer?
1. visceral organ musculature- includes development of smooth and cardiac muscle
- 2. pharyngeal arch muscles
- include muscles of facial expression, chewing, swallowing, and some head neck muscles
3. axial muscles
4. limb muscles
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What are the muscles that move mandible superiorly?
masseter and temporalis
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What are the muscles that move the mandible laterally?
buccinator and pterygoid
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What are the muscles that protract, retract, depress, elevate, and move the tongue laterally?
extrinsic tongue muscles
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What happens as a person swallows?
muscles grouped as suprahyoid contract to prevent food from entering into respiratory tract
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What happens when swallowing is complete?
infrahyoid muscles contract to return the hyoid bone to its original position
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Why does other muscle contraction occur?
to prevent food from entering nasal cavity and to ensure that it enters the esophagus
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