5.g Muscle Organization

Tension

created by the contraction of skeletal muscle fibers → tendons → skeleton/bone → movement

Insertion

moveable end of the muscle that attaches to the bone being pulled; Fetch ??

Origin

end of the muscle attached to a fixed/stabilized bone; Stays

Prime Mover/Agonist

principal muscle involved in an action (e.g. biceps brachii in lifting cup); Creates bulk of movement

Synergist

assists agonist in performing movement; stabilizes the bone attachment for the prime mover’s origin

Antagonist

muscle performing the opposite action of the prime mover to maintain body position and control rapid movement

Skeletal muscles that do not pull against the skeleton

Facial, Diaphragm, Tongue, Sphincters

Fascicle Organization

EpPeEn

Epimysium

covers entire muscle

Perimysium

covers bundled muscle fibers (fascicles)

Endomysium

covers individual muscle fibers

Parallel

fascicles arranged in the same direction as the long axis (e.g. biceps brachii)

Central Body/Belly

large mass of tissue located in the middle of the muscle between the insertion and the origin; become enlarged during contraction

Fusiform

parallel muscle having a central, large belly that is spindle-shaped (tapers as it extends to its origin and insertion)

Circular/Sphincters

concentrically arranged bundles (e.g. orbicularis oris)

Relaxed

opening size is increased

Contracted

opening shrinks to the point of closure

Convergent

muscle has a widespread expansion over an area but the fascicles come to a single, common attachment point (e.g. pectoralis major)

Pennate

blend into a tendon that runs through the central region of the muscle for its whole length

Unipennate

fascicles on one side of tendon (e.g. extensor digitorum)

Bipennate

fascicles on both sides of tendon (e.g. rectus femoris)

Multipennate

muscle fibers wrap around tendon (e.g. deltoid)

Ad

to; toward

Ab

away from

Sub

under

Ductor

something that moves

Anti

against

Epi

on top of

Apo

to the side of

Longissimus

longest

Longus

long

Brevis

short

Maximus

large

Medius

medium

Minimus

tiny; little

Rectus

straight

Multi

many

Uni

one

bi/di

two

Tri

three

Quad

four

Externus

outside

Internus

inside