1B - Joints, Cartilage, Muscles Flashcards
joints
areas where two or more bones join together
fibrous joints
articulating bones connected by fibrous tissue in which there is almost no movement ex. sutures in skull
cartilaginous joints
allow only slight movement and consist of bones connected entirely by cartilage (hyaline or fibrocartilage)
synovial joints
created where two bones articulate to permit a variety of motions, have synovial fluid
synchondroses
primary cartilaginous joint - early life bone development
ex. epiphyseal plates
symphyses
secondary cartilaginous joint - strong, slightly moveable joints, united by fibrocartilage
ex. pubic symphysis
saddle joint
synovial joint, found at the base of thumb; allows grasping and rotation
ball and socket joint
synovial joint - hip and shoulder joints
- multi axial
- high mobility, low stability
- have labrum to improve joint contact
condyloid joint
synovial joint, does everything except rotating (flexion, extension, adduction, abduction)
ex. wrist
pivot joint
synovial joint, allows for rotation around the length of a bone, only allows rotation
ex. radial head next to ulna
hinge joint
synovial joint between bones that permits motion in only one plane
ex. humerus and ulna at elbow
- uniaxial
- more stability, lower ROM
plane joint
synovial joint that allows only gliding movement
ex. between carpals and tarsals
what 5 structures make up synovial joints
bones, ligaments + capsules, tendons/muscles, intra-articular structures, bursae
ligaments
connective tissue structures that bind bones together, non contractile
simple joint
a joint with only two skeletal components
ex. elbow
stability in joints
comes at expense of range of motion
what are the 3 factors that affect stability + ROM
- shape and arrangement of articulating surfaces
- ligaments that cross the joint - more + tighter ligaments = more stability
- tone of surrounding muscles
range of motion
the range through which a joint can be moved, comes at expense of stability
complex joint
two surfaces with articular disc or fibrocartilage
ex. knee
tendons
connect muscle to bone
sprain
injury to a ligament
strain
injury to muscle tendon
non-contractile tissue
tissue that cannot actively shorten
ex. skin, ligament, cartilage
grade 1 sprain
stretching or slight ligament tearing, mild tenderness, swelling, and stiffness
grade 2 sprain
incomplete tear with moderate pain, swelling, and bruising
grade 3 sprain
complete tear of ligaments with severe swelling, bruising, and instability
treatment of sprains
PRICE, Protection, Rest, Ice, Compression, Elevation
intra-articular structures
contribute to synovial joint function
extracapsular ligaments
reinforce capsule, stabilizing ligaments located outside joint capsule
intracapsular ligaments
within a joint but excluded from synovial cavity, stabilizing ligaments located inside joint capsule
articular discs
pads composed of fibrocartilage, minimize wear and tear on the bone surfaces. absorb shock and distribute weight
labrum
fibrocartilaginous lip extending from the edge of a joint to deepen the socket and improve bony contacts. common in ball and socket joints
bursa
fluid-filled sac that reduces friction between moving parts (bones and tendons, bones and ligaments, etc.)
- protect structures from each other
- fibrous capsules lined with synovial fluid
tendon sheaths
elongated bursa wrapped completely around tendon subjected to friction
bursitis
chronic inflammation of a bursa caused by irritation from repeated excessive exertion of a joint, trauma, acute chronic infection, or rheumatoid arthritis
suture
interlocking line of union between bones
gomphosis
fibrous joint, attachment of a tooth to its socket
syndesmosis
a fibrous joint at which two. bones are bound by long collagen fibres
ex. tib-fib
fibrocartilage
cartilage that contains fibrous bundles of collagen, very durable and strongest type of cartilage
ex. menisci, intervertebral disc, pubic symphysis
what is the function of fibrocartilage?
shock absorber, support and join structures
elastic cartilage
specialized tissue with abundant elastic fibres, more flexible than hyaline cartilage
ex. epiglottis, outer ear, eustachian tubes
what is. the function of elastic cartilage?
provides strength and elasticity to maintain shape of structures
hyaline/articular cartilage
has a smooth surface that provides flexibility and support at joints
found on the ends of long bones, ribs, and nose
- dense viscoelastic connective tissue
- covers the articulating ends of bones within synovial joints
most common and weakest cartilage
hyaline cartilage
what does hyaline/articular cartilage not have?
no blood supply, no lymph channels, no neurological supply
- important because makes injury hard to detect and can’t repair on its own
what is the function of hyaline cartilage?
- distributes mechanical load over a wider area to decrease stress/pressure on joint surfaces
- reduce friction to minimize wear and allow relatively free movement of the opposing joint surfaces
composition of hyaline cartilage
cells (chondrocytes, less than 10%) and extracellular matrix
chondrocytes
mature cartilage cells
manufacture, secrete, organize and maintain ECM
extracellular matrix
the chemical substances located between connective tissue cells
- interstitial fluid (water, lipids, dissolved electrolytes)
- collagen
- proteoglycans
cartilage loading
compression forces interstitial fluid out of the cartilage into the joint capsule. when the load is removed, fluid flows back into the cartilage with new nutrients
what is the purpose of cartilage loading?
nutrient exchange and replenishment
cartilage is _________
avascular
osteoarthritis
unilateral “wear and tear” injury where joint cartilage is gradually lost, causing pain. Most common type of arthritis and cause of hip and knee replacements
rheumatoid arthritis
Bilateral, chronic autoimmune disorder in which the joints and some organs of other body systems are attacked. Inflammation of joint linings (synovial membrane) and cartilage. As cartilage degrades fibrous tissue joins exposed bone ends making them immovable
what are the 3 types of muscle
skeletal, cardiac, smooth
skeletal muscle
a muscle that is attached to the bones of the skeleton and provides the force that moves the bones, multi-nucleated, striated
skeletal muscles are under ___________ control
voluntary
cardiac muscle
involuntary muscle tissue found only in the heart, striated, single nucleus
smooth muscle
involuntary muscle found inside many internal organs of the body, viscera and blood vessels and skin
- not striated
- single nucleus
4 functions of muscle tissue
- produce body movements
- stabilizing body positions
- producing heat (thermogenesis)
- storing + moving substances in the body
4 properties of muscle tissue
- electrical excitability - able to respond to stimuli
- contractility - attached to bone via tendons
- elasticity - returns to original length after contraction and extension
- extensibility - can stretch without being damaged
myosin
the contractile protein that makes up the thick filaments of muscle fibers
actin
the contractile protein that makes up the thin filaments of muscle fibers
autorhythmicity
hearts ability to control its own contractions
electrical signals
audtorhythmicity in the heart
chemical signals
action potential signals received at neuromuscular cleft
periosteum
a dense fibrous membrane covering the surface of bones (except at their extremities) and serving as an attachment for tendons and muscles
fascicle
bundle of myofibres
myofibre
individual muscle cell
epimysium
covers the entire skeletal muscle
perimysium
the connective tissue that surrounds fascicles
endomysium
connective tissue surrounding a myofiber
myofibril
tightly packed filament bundles found within skeletal myofibres
sarcomere
a structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band
Z line
the line formed by the attachment of actin filaments between two sarcomeres of a muscle fibre in striated muscle cells
- two sets of actin fibres are going to join together
M line
supporting proteins that hold the thick filaments together in the H zone
- where two sets of myosin fibres are going to join together
I band
region within myofibril where only actin is present
H band
region within myofibril where only myosin is present
A band
full length of where myosin is (can overlap with actin). always the same width
myosin heads
bind to specific sites on actin molecules to from cross bridges
- 2 heads
- actin binding head and ATP binding head
one myosin head binds to _____ and the other binds to ___
actin and ATP
tropomysin
form a long chain that cover “active sites” on a thin filament (actin); preventing actin-myosin interaction
upper motor neuron
originates in cerebral cortex or brainstem and terminates on a lower motor neuron. Brain to spinal cord
lower motor neuron
motor neuron in the peripheral nervous system with its nerve fibre extending out to the muscle and only its cell body in the central nervous system. Spinal cord to periphery
motor neurons
neurone that carry outgoing information from the brain and spinal cord to the muscles and glands
contralateral
defines how innervation is on the opposite side of the body
principle of orderly recruitment
the theory that motor units generally are activated on the basis of a fixed order of recruitment, in which the motor units within a given muscle appear to be ranked according to the size of the motor neuron
Henneman size principle
the recruitment of motor units within a muscle proceeds from small motor units to large motor units
low force contractions
small motor units recruited
high force contractions
large motor units recruited
force production
motor unit size + firing frequency
slow oxidative fibre
a type of muscle fibre that is the smallest in diameter, the least powerful, dark red in colour due to large amounts of myoglobin and many blood capillaries; it is a fatigue-resistant fibre adapted to maintain posture and for aerobic, endurance activities like running a marathon
fast glycolytic fibre
a type of muscle fibre that is the largest in diameter, the most powerful, and is pale in colour due to the low myoglobin content and few blood capillaries; adapted for intense anaerobic movements of short duration such as weight lifting
fast oxidative-glycolytic fibre
a type of muscle fibre that is intermediate in diameter and dark red in colour due to large amounts of myoglobin and many blood capillaries; used in walking and sprinting
Type 1
slow oxidative, slow fatigue rate, low force
type 2a
fast oxidative glycolytic, medium fatigue rate, medium force
type 2x
fast glycolytic, fast fatigue rate, high force
sliding filament theory
theory that actin filaments slide toward each other during muscle contraction, while the myosin filaments are still
- actin filaments slide over myosin, creating a shortening effect (Z disks move closer together)
cross-bridge formation
high-energy myosin head attaches to thin filament, which is a repetitive cycle producing muscle contraction
bound state
myosin has bound to actin and is stuck there
power stroke
release inorganic phosphate from myosin, causing a transformation
rigor state
inorganic compound has been removed, myosin has contracted, and is stuck
relaxed state
when ATP binds
binding state
cycle can be repeated
what element, when it binds to the troponin complex, makes tropomyosin roll away
calcium
troponin complex
the regulatory proteins that control the position of tropomyosin on the thin filament
what is the first step in excitation-contraction coupling
calcium release
force-length relationship
sliding filament sarcomere structure has implications for muscle force production. when a muscle is maximally activated, the isometric force that is produced is dependent upon muscle length
isometric force
the generation of force without muscle movement
ascending limb
sarcomeres shortened, mechanism for reduced force unknown. shorter limb = less force
plateau
optimal overlap of actin/myosin = maximal cross bridges = maximal force
descending limb
as length increases, fewer actin sites overlap myosin
passive muscle stretch
activates spindle stretch receptors and causes increased rate of action potentials in the afferent neuron
degree of muscle activation
number of active sarcomeres. Determines force produced
parallel elastic component
passive elasticity derived from muscle membranes
force-velocity relationship
as speed of contraction increases, the force it is able to exert decreases
isometric
high force, velocity = 0
- no movement
concentric
low force, high velocity, cross bridges can only go so fast
- shortening
eccentric
poorly understood
- lengthening
torque
force x moment arm. muscles can only produce so much force, but we can change the angle at which it acts and therefore change the moment arm
moment arm
perpendicular distance from an axis to the line of action of a force. changes depending on angle of insertion
sliding filament theory states (5)
- bound state
- power stroke
- rigor state
- relaxed state
- binding state
pennation angle
angle at which muscle fibres all connect together in the tendon
unipennate muscle
all the muscle fibres are on the same side of the tendon
bipennate muscle
muscle fibres on both sides of the tendon; rectus femoris
multipennate muscle
has branches of the tendon within the muscle
grade 1 strain
overstretching leading to localized pain, minimal swelling, and tenderness
grade 2 strain
partial tearing of muscle or tendon
grade 3 strain
a palpable defect of the muscle, severe pain, an d poor motor function
symptoms of strains
swelling, bruising or redness, pain at rest, inability to use muscle or muscle weakness
first aid for strains
Protections
Rest
Ice
Compression
Elevation
fibrous connective tissue
dense tissue, large number of collagen fibres organized into parallel bundles
- includes ligaments and tendons
adipose
fat tissue
what age and onwards has progressive muscle loss with aging?
30
increased bone density
increased mineral density and calcium absorption increase bone strength as a result of weight-bearing activities, prevents osteoporosis
firing rate
the rate at which a neuron produces action potentials; usually expressed in terms of spikes per second
