Muscle Function pt 1 Flashcards
3 types of muscle
skeletal
cardiac
smooth
muscle fiber types
Type IA
Type IIA
Type IIB
can individual muscles have different fiber types?
yes
an individual muscle can contain multiple fiber types
how are variations of muscle fibers believed to be determined?
genetically
Type I muscle fibers visually
dark (d/t containing larger numbers of mitochondria and a high concentration of myoglobin)
how are type I muscle fibers referred to
slow-twitch or slow oxidativve
do type I muscle fibers contract over a long or short period of time
long period of time
type IIB muscle fibers visually
pale (d/t fewer mitochondria and only small amounts of myoglobin)
how are type IIB fibers referred to
fast-twitch or fast glycolytic
which muscle fiber type are largest in diameter
type IIB
what happens as the muscle fiber’s diameter increases
it generates more force
which muscle fiber will twitch quicker
type IIB
which muscle fiber fatigues the quickest
type IIB
type IIA fibers visually
intermediate in characteristics
-middle amounts of mitochondrion and myoglobin
-fiber diameter is smaller than IIA but larger than I
-don’t fatigue as quickly as type IIA, but don’t last as long as I
-speed of contraction is quicker than type I, but slower than IIA
how are type IIA muscle fibers referred
fast oxidative-glycolytic
what are muscles with a high proportion of type I fibers able to do
carry on sustained activity d/t the fibers not fatiguing quickly
what muscles are considered to have high proportions of type I fibers
stability and postural muscles
ex: soleus, adductor pollicis, tibialis anterior
what are muscles with a high proportion of type IIA fibers referred to as
mobility or non postural or phasic muscles
what do muscles with high proportions of type IIA fibers do
-produce larger ROM
-respond quickly to a stimulus
-fatigue more rapidly
ex: biceps brachii
what happens when structure and function match
things work well
what happens when structure and function do not match
there will be breakdown
2 types of material found in skeletal muscle
muscle tissue (contractile)
connective tissue (non-contractile)
elasticity
the ability of soft tissue to return to its resting length after a passive stretch
d/t primarily non-contractile tissue
contractility
refers to the muscle’s ability to develop tension
d/t contractile tissue
irritability
refers to the muscle’s ability to respond to chemical, electrical or mechanical stimuli
what is a chemical stimuli
ACh @ the neuromuscular junction
muscle relaxers
what is a electrical stimuli
action potential
stim
what is a mechanical stimuli
deep tendon reflex
what is the morphology of a muscle
refers to how the muscle fibers are aligned with the tendon
types of morphology
parallel
oblique
spiralized
what does the alignment of the fibers affect
the physiologic cross-section of the muscle
the muscles ability to shorten
how is the physiologic cross section measured
transecting each fascicle at a right angle
perpendicular to the fibers
the larger the physiologic cross section
the greater the ability to produce tension
the further a fiber can shorten
the greater ROM it can move the bony lever
what are parallel muscles
the fasciculi of the muscle are parallel to the long axis of the muscle
how do the fibers run w/in parallel muscles
run the length of the muscle
or
attached end-to-end
how much shortening can a parallel muscle undergo
roughly 50% of its length
what do parallel muscles produce
a greater ROM
they are good for producing ROM
3 types of parallel muscles
quadrilateral
strap
fusiform
quadrilateral
parallel muscle
flat, short muscles
ex: hyoid muscles and rhomboids
strap muscle
parallel muscle
the fasciculi are long and extended throughout the length of the muscle
how can the fibers lie in a strap muscle
some have very long fibers (ex: sartorious)
some have tendinous inscriptions along the way (ex: rectus abdominis)
fusiform muscle
parallel muscle
most but not all muscle fibers extend throughout the length of the muscle
muscle belly is rounded w/ tapering ends
fibers curve b/w origin and insertion
ex: biceps brachii
what are fusiform muscles good at doing
producing ROM
oblique muscle
the fiber arrangement is oblique to the muscle’s long axis
usually more fibers are in oblique muscles
fibers tend to be shorter in oblique muscles
what happens d/t oblique muscles having a larger # of muscle fibers
only a portion of the force of the muscle goes towards producing motion of the bony lever
they are able to transmit a large amount of force to the tendon to which they attach
which muscle has a greater physiologic cross-section
oblique muscles
increases their ability to produce tension
what are oblique muscles good at
producing tension
2 types of oblique muscles
triangular
pennate
triangular muscle
oblique muscle
one wide attachment and one narrow attachment
ex: pec major and temporalis
pennate muscle
the fiber arrangement resembles that found in a feather
types of pennate muscles
unipennate
bipennate
multi-pennate
circumpennate
unipennate muscle
obliquely set fasciculi fan out on only one side of a central muscle tendon
ex: flexor pollicis longus
bipennate muscle
fasciculi are obliquely set on both sides of a central tendon
ex: rectus femoris, gastrocnemius
multi-pennate
the oblique fasciculi converge on several tendons
ex: deltoid
circumpennate
the fibers surround the centrally located tendon
ex: anterior tibilais muscle
spiralized muscle
the fibers spiral around the long axis
the fibers will wind and unwind
what does the strength of a contraction depend on
the size and number of contracting fibers
what is maximal strength determined by
the total cross-sectional size of all its fibers
parallel muscle cross sectional size
size of all of the fibers is the same as the cross sectional area of the muscle
pennate muscle cross sectional size
more muscle fibers
the total cross sectional size of the fibers is greater than the cross sectional area of the muscle
which muscle would you prefer for force production
oblique muscles
which muscle would you prefer for ROM (excursion)
parallel
