Joints
Articulations
Arthroses
Joints, defined
•  Points of contact between
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Two bones
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Bone and teeth
Joint classification: 2 schemes
•  Functional classification
–  degree of movement permitted
•  Structural classification
–  Anatomical organization
•  type of binding material
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Functional Classification
•  Based on degree of movement
•  3 categories
–  Synarthroses (singular is synarthrosis)
–  Amphiarthroses (singular is amphiarthrosis)
–  Diarthroses (singular is diarthrosis)
Synarthroses
•  immovable joints
•  Strong
•  4 types
–  Sutures
–  Gomphoses
–  Synchondroses
–  Synostoses
Sutures
•  dense fibrous connective
tissue
•  Example:
–  cranial sutures
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Gomphoses
•  fibrous connective tissue
(periodontal ligament)
•  Example:
•  teeth and sockets (alveoli)
Synchondroses
•  hyaline cartilage
•  Examples:
–  Epiphyseal cartilages
–  R1 and manubrium
Synostoses
•  Fused bones
•  Examples:
–  L and R frontals fuse to
a single frontal bone
–  Epiphyseal line
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Amphiarthroses
•  Bones united by
–  cartilage
–  or
–  collagen fibers
•  Strong
•  Slightly movable
•  2 types
–  Syndesmoses
–  Symphyses
Syndesmoses
•  Fibrous connective tissue
organized into bundles or
sheets
•  Examples:
–  distal tibiofibular joint
–  interosseous membranes
Symphyses
•  Bones are attached
by fibrocartilage
•  Examples:
–  pubic symphysis
–  intervertebral discs
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Diarthroses: Synovial joints
•  Most joints
•  Freely movable
•  Components
– Articular capsule
– Articular cavity
– Articular cartilage
– Synovial membrane
articular (joint) capsule
•  Like a finger trap
articular (joint) capsule
•  Encloses the space where two
bones come together
•  Composed of dense
connective tissue
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articular (joint) capsule
•  Encloses the space where two
bones come together
•  Composed of dense
connective tissue
articular cartilage
• composed of hyaline cartilage
• provides a smooth surface for movement
• provides a little shock absorption
Synovial Fluid
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consists of interstitial fluid plus proteoglycans
honey-like when joint is immobile,
movement thins it; becomes watery
use of joint causes increased production of synovial
fluid
•  Functions of synovial fluid
–  lubrication of joint
–  shock absorption
–  nutrient distribution
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Joint Accessories, they’re hip!
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Cartilages and fat pads
Ligaments
Tendons
Bursae
Cartilages
•  Menisci (s. mensicus)
also called articular
discs
–  pads of fibrocartilage
–  stabilize joints by
improving the fit
Fat pads
•  covered by synovial
membrane
•  protection of joint and
bones
•  packing material of
joints
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Ligaments and tendons
confer stability to joints
•  Ligaments
–  support, strengthen, and
reinforce joints
–  some make up articular
capsule
•  Tendons
–  limit range of motion of
joints
Bursae and Tendon Sheaths
•  Filled with synovial fluid, lined by synovial membrane
•  Bursae, pl (singular is bursa) (defined = pouch)
–  between bone and skin, tendons,
ligaments, or muscles
•  Tendon Sheaths
–  Tube-like bursae
Factors stabilizing synovial joints
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joint capsule
other ligaments
shape of articulating surfaces
menisci
tension in associated muscles and tendons
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Nerve supply (innervation)
•  Nerve endings supply
–  articular cartilage
–  ligaments
•  Information relayed
–  regarding pain
–  degree of movement
Blood supply
•  all joint components
•  excepting articular cartilage
–  nutrient/waste exchange is via synovial fluid
•  pumping action…discussed earlier
Movements at Synovial Joints
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Linear motion /gliding
Angular
Circumduction
Rotation
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Movements at Synovial Joints
•  Linear motion /gliding
•  Tarsals
•  Carpals
Movements at Synovial Joints
Angular motion
•  Flexion
–  Decrease joint angle
•  Extension
–  Increase joint angle
•  Hyperextension
–  Increase beyond
anatomical position
•  Abduction
–  Away from body
•  Adduction
–  Toward body
Movements at Synovial Joints
•  Rotation
•  Multiple types
–  Supination
–  Pronation
–  Medial rotation
–  Lateral rotation
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Movements at Synovial Joints
•  FYI only * useful for lab
•  Others
–  Circumduction
–  Inversion
–  Eversion
–  Dorsiflexion
–  Plantar flexion
–  Opposition
–  Protraction
–  Retraction
–  Elevation
–  Depression
Types of Synovial
joints
FYI only
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Gliding joints
Hinge joints
Pivot joints
Ellipsoid joint
Saddle joint
Ball-and-socket joint
No test questions from
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9-4 intervertebral articulations
9-5 shoulder and elbow
9-6 hip and knee
9-7
9-8
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Arthritis: inflammation of synovial
joints; impairs joint mobility
•  Result of damage to
articular cartilage
•  Cause of damage varies
•  Many types
•  Pain, stiffness, swelling
Effects of Aging on Joints
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↓’d production of synovial fluid
articular cartilage thins with age
loss of flexibility in ligaments, due to less use
wear and tear and genetic factors may
exacerbate these aging effects
•  Note: Disuse causes ↓’d amount of synovial
fluid, ↓’d flexibility of ligaments/tendons,
muscular atrophy leads to less use…
Using your joints
•  Hyaline cartilage lacks direct circulation
Acute use and training effects
•  Both increase the thickness of cartilage
•  Because cartilage absorbs synovial fluid
•  15% increase in thickness w/in 15 minutes
•  Benefits:
–  1 increase of exchange
–  2 increases contact area, decreases chance of injury
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