Muscle Fibers
What membrane directly surrounds muscle fibers?
endomysium
What is the contractile unit in the Hill muscle model?
sarcomeres/myofibrils contracting according to the sliding filament theory
What characteristic is unique to muscles?
contractility: the ability to generate active tension
What is a motor unit?
a neuron and all muscle fibers innervated by it
What are three ways muscle can be attached to bone?
directly, via tendon, via aponeurosis
What is a bundle of muscle fibers called?
muscle fascicle
What is represented by the parallel elastic component?
membranes in the muscles (epi/peri/endomysium)
What is extensibility?
The ability to stretch
Why would it be beneficial for one neuron to innervate very few muscle fibers?
What measure of a muscle is directly proportional to the amount of force generated by a muscle?
physiologic cross-sectional area
What are the two major arrangement types of muscles?
parallel and pennate (penniform)
What is represented by the series elastic component of the Hill muscle model?
tendons
What is elasticity?
The ability to return to normal length after stretch
What sizes of motor units are recruited first?
smaller
What is the benefit of having most levers in the human body place muscles at a mechanical disadvantage?
they can generate faster movements and require less displacement of the muscle to create larger movements
What muscle fiber arrangement leads to larger changes in length?
parallel
Which elastic component has the much larger impact on the behavior of muscles?
tendons
What is irritability?
the ability to respond to a stimulus
What order of motor unit recruitment is followed?
Type 1 slow twitch first, type II fast twitch oxidative second, type IIb fast twitch glycolytic third
Draw how CSA and PCSA are measured in a parallel muscle fiber arrangement
straight across in both
What muscle fiber arrangement is better for strong force production?
pennate/penniform
Draw and label the Hill muscle model
should include parallel and series elastic components and contractile component
What kind of pennation angle allows more force from a muscle fiber to be directed in the direction of the line of action of the muscle?
small
What is a crossed extensor reflex?
stepping on something sharp, ipsilateral flexion, contralateral extension
Draw CSA and PCSA measurements in pennate/penniform muscle fiber arrangements
CSA--straight across, PCSA--perpendicular to muscle fiber direction