Articulations
• junction of 2 bones
• MOTION OCCURS AT A JOINT -- NOT
AT A LIMB
– i.e. elbow flexion NOT forearm flexion
Classification of joints
• Synarthroses - fibrous joint with little or
no movement
• Amphiarthroses - cartilaginous joints
with some motion
• Diarthroses - (aka synovial) - freely
movable joint
Joint Classification
• based on
– number of axes of rotation
– number of planes of motion
– e.g. uniaxial -- 1 axis of rotation so 1 plane
of motion
Ball and Socket = Triaxial
e.g., flexion & extension
internal & external rotation
abduction & adduction
Condyloid = Biaxial
e.g., flexion & extension
internal & external rotation
Hinge = uniaxial
e.g., flexion and extension
Pivot = uniaxial
e.g., supination
& pronation
Gliding = no axes
‘gliding between
2 flat bones’
Saddle = biaxial
same as condyloid
but greater ROM
Ellipsoidal = biaxial
e.g., flexion & extension
abduction & adduction
Structure of Synovial Joint
A - articular (hyaline)
cartilage (1-7 mm)
– smooth elastic tissue on
ends of bone
– 60-80% water
– no blood supply
– absorbs shock,
distributes force and
provides a low friction
surface
Structure of Synovial Joint
B - fibrous capsule
– very fibrous collagen
tissue used to hold bones
together
C - synovial membrane
– lines the joint cavity
– secretes synovial fluid to
lubricate and provide
nutrition
NOTE: B & C combine to form the articular capsule
or joint capsule
Structure of Synovial Joint
D - ligaments
– connect bone-to-bone
– usually restrict ROM
at a joint
• tendons (not shown)
– connect muscle-tobone
A* - Joint cavity
Other Structures of Synovial
Joints
• bursa
– small capsules lined with synovial
membranes
– reduces friction between other
structures in the joint
Olecranon
bursa
• tendon sheaths
– fascia surrounding tendon to
reduce friction between tendon and
surrounding structures
Digital
synovial
sheath
Other Structures of Synovial Joints
articular fibrocartilage
– different from articular cartilage
– takes the form of a fibrocartilaginous
disc or partial disc
• distributes load over joint surface
• improve fit of articulating surfaces
• limit slipping of one bone relative to
other
• protect periphery of articulation
• lubricate articulation
• absorb shock
close-packed vs. loose
packed
close packed
position
– maximum contact
area
– minimum mobility
– maximum stability
Bony Stability (cont.)
• amount of contact area
Joint Stability - Connective
Tissue
• ligamentous support
Properties of Connective
Tissue
• elasticity
– ability to return to normal state after stretch
– elastic limit
• stretch beyond this limit will cause permanent
damage
• plasticity
– stretched too far such that does not return
to its normal state
• ligament sprain (worse than bone fracture)
Exercise
will help
increase
the loads
a ligament
or tendon
can sustain
elastic
limit
Sprains occur in this region
plastic
Sprains result
in decrease of
joint stability
deformation (length)
Joint Stability - Muscles
• muscular
arrangement
– ability of muscle to
provide support
– muscle fatigue
• cruciate rupture more
likely when muscle is
fatigued
Mobility
• degree to which an articulation is
allowed to move before being restricted
by surrounding tissues
• ROM a.k.a. flexibility
Stability v. Mobility
• trade-off between stability and
mobility
–increase stability decrease
mobility
–vice-versa
Neuromuscular Response to
Stretching
•Sensory neurons provide feedback on
the characteristics of the muscle or
other tissues.
2 neuromuscular proprioceptors:
MUSCLE SPINDLES &
GOLGI TENDON ORGANS
Muscle Spindles
• location:
– interspersed throughout muscle
belly
• responds to:
– muscle length
– muscle velocity
• causes:
– autogenic facilitation
– reciprocal inhibition
Stretch Reflex
• The muscle spindle is responsible for the stretch
reflex.
• As a muscle is rapidly stretched, the muscle
spindle responds by facilitation of the same
muscle and inhibition of the antagonistic
muscle.
• This reflex can be seen in the patellar tendon
tap.
Golgi Tendon Organ
• location:
– near the muscle-tendon
junction
Muscle Fibers
GTO
• responds to:
– muscle tension
• causes:
– autogenic inhibition
– antagonistic facilitation
tendon
GOLGI TENDON ORGAN
“My Little GTO”
• possibly the critical determinant to maximal
lifting levels in weight training
• may also be responsible for uncoordinated
responses in untrained individuals
• response is adapted through training
BALLISTIC
activate muscle
spindles which
elicits a stretch
reflex
STATIC
if static position
achieved slowly then
can minimize muscle
spindle response
if held for sufficiently
long period (~30s) then
can elicit GTO
response
may result in
tearing a muscle
STATIC BETTER THAN BALLISTIC
Spindle response: minimal if performed slowly
GTO response: active stretch of hip extensors
causes GTO to relax hip extensors and to
activate the hip flexors
motive force: actions of the hip flexors
consequences: no negatives -- limited ROM
limits possibility of injury and exercise
antagonists
ACTIVE
STRETCH
Spindle response: minimal if performed slowly
GTO response: passive stretch of hip extensors
causes GTO to relax hip extensors
motive force: external force
consequences: no direct control of ROM thus
may exceed physiological limits and induce
muscle damage
PASSIVE
STRETCH
Stretching
• Proprioceptive Neuromuscular Facilitation
• PNF
– alternating contraction - relaxation of agonist &
antagonist muscles
– takes advantage of the response of the proprioceptors
– e.g. hamstrings
• passive static stretch of hams - relax
• active maximal concentric action of hams - relax
• repeat
Plyometric Training
Plyometric training consists of exercises that rapidly
stretch a muscle followed immediately by a
contraction. They improve power output in the muscle
by:
Neurological Influences: rapidly stretching of the
muscle, which excites the motoneurons via the stretch
reflex.
Structural Influences: involving elastic energy from
the stretch-shortening cycle.
Arthritis
• Refers to more than 100
different diseases that
affect areas in or around
joints.
• The disease also can
affect other parts of the
body.
• Arthritis causes pain,
loss of movement and
sometimes swelling.
•Affects women more
than men
Source: Arthritis Foundation – www.arthritis.org
Osteoarthritis
20.7 million
Mostly after age 45
Rheumatoid
2.1 million
Mostly women
Juvenile
Arthritis
285,000
Under age 17
Juvenile Rheumatoid
Arthritis (JRA)
50,000
Arthritis
Fibromyalgia
3.7 million
Mostly women
Gout
2.1 million
Mostly men
Spondylarthropathies
412,000
Lupus
239,000
Source: Arthritis Foundation – www.arthritis.org
Osteoarthritis (OA), or degenerative
joint disease, is one of the oldest and
most common types of arthritis,
characterized by the breakdown of the
joint's cartilage. Cartilage is the part of
the joint that cushions the ends of bones.
Cartilage breakdown causes pain and
joint swelling. With time, there will be
limited joint movement.
• Most commonly affects middle-aged and older people
• Range from very mild to very severe
• Affects hands and weight-bearing joints (e.g., knees, hips, feet and back).
• OA is not an inevitable part of aging, although age is a risk factor
• Obesity may lead to osteoarthritis of the knees
• Joint injuries due to sports, work-related activity or accidents may be at
increased risk of developing OA.
Source: Arthritis Foundation – www.arthritis.org
Rheumatoid Arthritis (RA)
– a systemic disease that
affects the entire body.
• Characterized by the inflammation of the membrane lining the joint, which
causes pain, warmth, redness and swelling.
• The inflamed joint lining, the synovium, can invade and damage bone and
cartilage.
• Inflammatory cells release enzymes that may digest bone and cartilage.
• The involved joint can lose its shape and alignment, resulting in pain and
loss of movement.
• The disease usually begins in middle age, but can start at any age, and
affects two to three times more women than men.
Source: Arthritis Foundation – www.arthritis.org
Location of “Tender Points”
Fibromyalgia syndrome is a condition
with generalized muscular pain and
fatigue that is believed to affect
approximately 3.7 million people.
• The name fibromyalgia means pain in the muscles and the fibrous
connective tissues (the ligaments and tendons). The condition is known
as a syndrome because it is a set of signs and symptoms that occur
together.
• Fibromyalgia mainly affects muscles and their attachments to bones.
Although it may feel like a joint disease, it is not a true form of arthritis
and does not cause deformities of the joints. Fibromyalgia is, instead, a
form of soft tissue or muscular rheumatism.
Source: Arthritis Foundation – www.arthritis.org
Medicines
(e.g., analgesics, NSAIDS,
DMARDS, Disease Modifying
Anti-Rheumatic Drugs)
Use of Heat or Cold
Rest
Helpful before and after exercise
Many respond better
to cold packs than to heat
More rest and less activity are
needed during flares and the
opposite is true during periods of
improvement.
Exercise
(see next slide)
Surgery
joint replacement
Arthritis Treatments
Joint Protection
Careful use of joints to limit the pressure on the
involved joint
Simple and inexpensive devices available
Diet
Physical/Occupational Therapy
• Lack of vitamins associated with progression of
• recommend and teach prescribed muscle
OA of the knee
• Connection between obesity and OA of the knee
• Diet high in Omega 3 fatty acids may help reduce
inflammation in RA
• In general, people with arthritis are urged to
maintain a balanced diet and stay close to their
ideal weight.
strengthening and range-of-motion exercises
• teach non-medication ways to control pain
• suggest ways to make everyday and work
activities easier
Source: Arthritis Foundation – www.arthritis.org
Exercise
• Proper exercises performed on a daily basis are an important part of arthritis treatment.
• Exercise to help reduce weight can help prevent osteoarthritis in the knee.
• Proper exercise helps build and preserve muscle strength, keep joints flexible and help protect
joints from further damage.
Two categories of exercise:
• Therapeutic -- Prescribed by a doctor, physical therapist or an occupational therapist. These exercises are
based on individual needs and are designed to reach a certain goal.
• Recreational -- Includes any forms of movement, amusement or relaxation that refreshes the body and
mind. These exercises add to a therapeutic program, but do not replace it.
Three types of exercises:
•Range-of-motion -- Moving a joint as far as it comfortably will go and then stretching it a little further.
Range-of-motion exercises are designed to increase and maintain joint mobility that will decrease pain and
improve function.
•Strengthening -- Increases muscle strength to stabilize weak joints. These exercises use the muscle
without moving the joint.
•Endurance -- This type of exercise includes walking, swimming, bicycling, jogging, dancing and skiing.
These dynamic forms of exercise increase endurance, whereas range-of-motion and strengthening do not.
The most common risk in exercising is injury to joints and muscles. This usually happens from exercising
too long or too hard, especially if a person has not been active for some time.
Source: Arthritis Foundation – www.arthritis.org