Introduction to Muscles

Gross anatomy

muscle

investing connective tissue 1

endomysium

around individual muscle fibers [cells]

perimysium

around fascicles of fibers [bundles]

epimysium[intermediate membranes of the deep fascia]

tendons

continuous with epimysium and periosteum

Mechanics of muscle action

origin/insertion

action

isotonic contraction [shortening]

isometric contraction [tension developed]

eccentric contraction[lengthening]

roles

prime mover

antagonist

synergist

fixator

lever systems

class I

class I lever system

PFW

triceps brachii m—elbow j—forearm

class II

class II lever system

FWP

metarsophalangeal j—leg—gastrocnemius m

class III

class III lever system

WPF

forearm—biceps brachii m—elbow j



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