joint structure and muscle function Flashcards
Wolff’s law
bones will adapt based on stress or demands placed on them
joints are classified based on what 2 things
structure type
movement
3 structure types of joint classification
fibrous
cartilaginous
synovial
3 movement types of joint classification
synarthrosis
amphiarthrosis
diarthrosis
synarthrosis + example
immobile/nearly immobile joint
ex: SI joint or sutures in skull
amphiarthrosis + example
joint allows SOME movement –> has balance between mobility and stability
ex: spine at different levels (lumbar moves in different way than thoracic and cervical)
diarthrosis + example
free moving
ex: shoulders, hips
fibrous joints
joined together by fibrous interosseous connective tissue
suture joint
bone edges interlock one another
gomphosis joint
“peg in a hole” joint
like tooth and mandible/maxilla
syndesmosis joint
joined by interosseous ligament
ex: radius and ulna
or tibia and fibula
cartilaginous joints
connected by fibrocartilage or hyaline cartilage
symphysis joint
directly joined by fibrocartilage and covered with hyaline cartilage
ex: intervertebral joints + pubis symphysis
synchondrosis joint
connected by HYALINE cartilage
ex: first 7 ribs to sternum
or epiphyseal growth plates
synovial joints
no connective tissue directly unites bony surfaces
function of inner synovial layer of a synovial joint
provides lubrication, vascularization, and nutrition to the cartilage
characteristics of the outer fibrous layer of a synovial joint
dense, irregular connective tissue
varying thickness
poor vascularity + good innervation (wont bleed but it’ll hurt when you tear it)
ruffini joint receptor function
reacts to stretch/extremes of extension
pacini joint receptor function
compression/changes in hydrostatic pressure and joint movement
golgi (GTOs) joint receptor function
pressure + forceful joint motion into extremes of motion
unmyelinated free nerve ending joint receptor function
painful and unpainful mechanical stress or biomechanical stress
hyaluronate
viscosity of fluid and essential for lubrication
lubricin
cartilage on cartilage lubrication
t/f: nutrients and waste products diffuse in and out of synovial fluid
true
t/f: volume of synovial fluid decreases at an injured joint
false, it increases
which 2 joint receptor picks up increased pressure of an injured joint and signals
pacini + unmyelinated free nerve endings pick up the pain from this type of injury
function of menisci, labrums, and discs (3)
improve joint congruence
absorb compressive joint forces
increase stability
ligament functions (2)
align joint surfaces
guide/restrain motion
tendon functions (2)
transmit forces developed by muscles for motion
active joint stabilization
bursae function
protect soft tissue from shear force/friction of bones
hinge and pivot joints are examples of what classification of synovial joint
uniaxial
condyloid and saddle joints are examples of what classification of synovial joint
biaxial
ball-and-socket and plane joints are examples of what classification of synovial joint
triaxial
plane joint example
intercarpal joint
condyloid joint example
radiocarpal joint
saddle joint example
first carpometacarpal joint (thumb)
pivot joint example
proximal radioulnar joint
osteokinematics
movement of bones for physiologic joint motion
(plane, axis, and direction of movement; ex: flx/ext, ab/adduct,etc)
arthrokinematics
movement of the joint surfaces
(roll, slide/glide, spin)
open chain
movement takes place at one joint without causing motion at another joint
DISTAL segment is moving
closed chain
movement at one joint causes motions at other joints
PROXIMAL segment is moving
convex on concave movement
roll and glide occur in opposite directions
ex: humerus on scapula abduction –> roll inferior, slide superior
concave on convex
roll and glide occur in same direction
ex: tibia on femur extension –> roll anterior and slide anterior
close-packed
- full congruence of surfaces
-extreme ROM - joint is compressed and no more movement can occur
ex: patella with knee flexion cannot move
loose/open-packed
- incongruent surfaces
- mid-position
- allows for spin, roll, glide
- max loose packed position is at REST
soft end-feel
limited by soft-tissues
ex: elbow flexion
firm end-feel
limited by capsuloligamentous structures
ex: knee extension
hard end-feel
limited by bone
ex: elbow extension
cell that has a primary function of synthesizing the extracellular matrix
fibroblasts
3 types of fibroblasts
chondroblasts
tenoblasts
osteoblasts
2 components of the extracellular matrix
fibrillar component
interfibrillar component
fibrillar component of extracellular matrix is made of…
- elastin
- type I collagen to provide strength and functional integrity
interfibrillar component of extracellular matrix is made of…
proteoglycans and glycosaminoglycans
- that attract water to increase rigidity
- withstand compressive forces
what type of collagen primarily makes up ligaments and tendons
type I
collagen fiber alignment in tendons vs ligaments
ligaments = all directions
tendons = straighter
what type of collagen primarily makes up hyaline cartilage
type II
what type of collagen primarily makes up fibrocartilage
type I
hyaline cartilage
- on joint surfaces
- resists compressive forces
- avascular
fibrocartilage
- resists compressive AND tensile forces
- limited vascularity peripherally
(think discs + meniscus)
cancellous vs cortical bone
cancellous is the spongy inner layer
cortical is the compact outer layer
periosteum
fibrous membrane that covers the surface of bone
what type of collagen makes up bone
type I
isotropic material
display the same mechanical behavior no matter the direction of force applied
anisotropic material
behave differently depending on the size and direction of applied force
toe region of mechanical behavior
laxity in tissue straightens
elastic region of mechanical behavior
returns to original shape and size after being deformed
yield point region of mechanical behavior
point of no return
plastic region of mechanical behavior
residual deformation will be permanent
failure point of mechanical behavior
tear or break
tensile strain
forces pulling in opposite directions
shear loading
parallel forces pushing in opposite directions
torsional stress
parallel forces rotating in opposite directions
strain equation
(L2-L1) / L1
L1 = original length
L2 = final length
stiffness
resistance offered by material to external loads
brittle
little deformation before failure (older bone)
ductile
great deformation before failure (younger bone)
elastic region strain %
2-4%
plastic region strain %
4%-7.9%
grade I + II ligament sprains
young’s modulus
measurement of structure’s ability to withstand changes in length
macrofailure
rupture or avulsion
viscosity
resistance to flow (more fluid)
high viscosity = high resistance to deformation
how does temperature impact viscosity
high temperatures DIMINISH viscosity
elasticity depends on 2 things:
amount of collagen and elastin
creep
tissue deformation gradually continues if force is maintained
(ex: weight on elastic band)
stress-relaxation:
as tissue is stretched to a fixed length, less force is required to maintain that length overtime
stain-rate sensitivity
tissue response varies based on load speed
rapid load –> stiffer tissue
are tendons or ligaments more susceptible to tensile stress?
ligaments are
are tendons or ligaments better with multiple direction loading?
ligaments are
muscle stability is greatest in close or open packed positions?
close-packed
bones are most congruent so its easier to stabilize
2 components of a myofibril
actin
myosin
(myofilaments)
titin
maintains position of myosin during muscle contraction
z-discs
link together actin
a band
the contractile unit of the myofibril
I bands
only actin filaments
H zone
only myosin filaments
cross bridge interaction
- action potential
- Ca2+
- troponin
- actin becomes free
- myosin binds w actin
motor unit
alpha motor neuron and all muscle fibers it innervates
active muscle tension is affected by 4 things:
- # of muscle fibers in a motor unit
- diameter of the axon innervating motor unit
- # motor units firing at one time
- frequency of motor units firing
type IIA muscle fibers
fast oxidative glycolytic (INTERMEDIATE)
type IIB muscle fibers
fast glycolytic
(FATIGUES THE QUICKEST OUT OF ALL FIBERS)
superficial fascia function
contributes to mobility of skin and acts as insulator
deep fascia function
attach to muscle/bones and can form tracts, bands, or retinaculae
passive elastic component
adds passive tension and stiffness through connective tissue and tendons
stretching a muscle is considered to be what form of tension
passive
contracting a muscle is considered to be what form of tension
active
active insufficiency
decreased force capability due to a shortened state of agonist
active insufficiency is influenced by…
lengthening the state of the antagonist muscle
ex: flex fingers in neutral vs flexing fingers in wrist flexion
is force greater in eccentric, isometric, or concentric contractions
eccentric
label eccentric, isometric, and concentric contractions with a +,-, or 0 contractile velocity:
eccentric: -
isometric: 0
concentric: +
concentric vs eccentric
concentric is a shortened contraction with positive work
eccentric is a lengthening contraction with negative work (thing E for Elongation)
torque production varies with what 3 things
moment arm length
force length
velocity
isokinetic
constant angular velocity by changing torque through ROM
reverse action
proximal segment moves while distal segment remains stationary
like a pull-up
5 classifications for muscles
shape
number of heads
location
function
action or length of moment arm
antagonists have 2 jobs
reciprocal inhibition (allows agonist to contract)
co-contraction (stability)
passive insufficiency
the antagonist is not long enough to allow full ROM of all joints
wrist extension causing finger flexion is an example of what body mechanism
(bonus for the spinal level injury that uses this technique to grab things)
passive insufficiency
(c6)
muscle function if distal attachment lies CLOSE to the joint axis
rotation
muscle function if distal attachment lies AWAY from the joint axis
compression/stability
2 stretch reflexes
deep tendon reflex (GTO)
muscle spindle reflex
muscles in a SHORTENED position will __(increase/decrease)__ the NUMBER of sarcomeres and __(increase/decrease)__ the LENGTH of sarcomeres
decrease
length increase
muscles in a LONG position will __(increase/decrease)__ the NUMBER of sarcomeres and __(increase/decrease)__ the LENGTH of sarcomeres
increase
length decrease
when a muscle is lengthened for a long period of time, what direction does the tension curve shift? (left/right)
right!!
