Tissues of the MSK System 2 Flashcards
Ligaments, Muscles and Tendons
fxn of ligs
limits joint motion
guide bones as they are moved by muscles or outside forces
stabilizes joint at either extreme of motion
where are ligs more lax
mid range of joint motion
ligaments are –> vascularized
poorly vascularized
heal poorly
what are ligs made of
dense, organized CT
lines of fibers line up with the lines of force
what provides tensile strength to ligs
collagen
what do ligs contain varying amounts of
elastin
to provide suppleness
determines the amount of movement allowed
how are collagen fibers aligned –> ligs
parallel to the forces that the lig must resist
how do ligs attach
attachment to bone
how do ligaments attach to bone
collagen fibers –> fibrocartilage –> calcified cartilage –> bone
elastin content in a ligament is
variable
elastin content in cruciate ligs of knee
almost all collagen
very little elastin
resists tensile load w/ minimal elongation
therefore –> excellent knee stabilizer
elastin content of ligamentum flavum of spine
almost all elastin
very little collagen
can be stretched a lot before failure
poor ability to resist tensile loading
ligament failure is..
fxn of the load
what do ligs resist better
slow load better than fast load before failure
rapid loading –> ligs
intra-ligamentous lesion
slow loading –> ligs
injuries at or near the bone-ligament interface
ligament injuries are called
sprains
grades 1-3
ligament innervation
highly innervated
if there is very little pain after an injury –> ligs
injury may be more severe
if the ligament is torn –> there is less pain v. overstretch
less pain may equal more severe injury –> good diagnostic clue
muscle fxn
muscles move body parts
stabilize a joint
when muscles act as stabilizers…
reinforcing ligament fxn
what are muscles composed of
contractile tissue
non-contractile tissue
contractile tissue –> muscle
actin
myosin
sarcomeres
non-contractile tissue –> muscle
fascia surrounding muscle
3 layers
3 layers of fasica –> non-contractile tissue of muscle
endomysium
perimysium
epimysium
endomysium –> muscle
surrounds individual muscle fiber
perimysium –> muscle
surrounds groups of muscle fibers to form fascicles
epimysium –> muscle
surrounds muscle fascicles (outermost membrane) to encase entire muscle
what are forces generated by the muscle applied to
both contractile and non-contractile tissue
tension developed by contraction –> muscles
either or active or passive
active tension –> muscles
d/t contractile components
actin or myosin
passive tension –> muscles
d/t elastic properties of the contractile tissues w/in the muscle
how much can muscle fibers shorten
to about 50% of their original length
force of contraction is dependent on –> muscles
length of fibers
velocity of contraction
direction that fiber is moving in at time of contraction
how do muscles work
approximating insertion to origin
or
approximating origin to insertion
(usually works distal to proximal)
what do tendons do
connect muscles to other structures
tendons are compromised of
collagen
ground substance
cells
how is the collagen in tendons oriented
in line w/ the muscle’s pull
what do tendons do
transmit the force of muscle contraction to bone or other CT that they attach to
how much force can a tendon withstand
at least 2x the maximum force that muscles can exert on them
musculotendinous jxn
zone where muscle blends into tendinous tissue
typically…–> musculotendinous unit
transitional zone is weaker than the body of the muscle/tendon
what are some tendons surrounded by
tendon sheath or peritenon
example of tendon sheath
achilles tendon and flexor tendons of hand
what is a tendon sheath lined w/
synovial membrane
what does the tendon sheath do
lubricates the tendon for easier gliding
guides the tendon towards the bony attachment
failure in the muscle tendon unit may occur
in the muscle itself
in the musculotendinous jxn
in the tendon itself
at tendon-bone insertion
where does failure in the muscle tendon unit mostly occur
transitional points
