Joints
Articular System
Joints of the Body
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Avinash Bharadwaj
ANHB 2212 – Week 11
Joint Classification
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Fibrous Joints
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Structural and functional considerations
No perfect system
Arbitrary and confusing terms
Latin terminology and anglicised versions
“Articulation” / Articular / Arthrology
Articulatio / Arthron
Where two or more bones or
parts of bones unite…
How are they joined together…
the tissues that unite bones
Essential feature : fibrous tissue joining
bones
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Fibrous Joints – Sutures
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Between flat bones of the skull
Variety of bony margins
Between (many) bones of the skull
Fibrous tissue (ligaments) between other
bones
Aren’t all ligaments fibrous joints?
“Bones of the skull” and “other” bones :
Difference explained next week
Fibrous Joints – Syndesmoses
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n
True syndesmosis – inferior
tibiofibular
Interosseous membranes
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n
n
Bone
Periosteum
•Unossified areas
•Spread of ossification
•Disappearance with age
Separation of compartments
Additional areas for muscle
attachments
Some other ligaments now
termed syndesmoses
Gomphosis :
Tooth and bone
1
Cartilaginous Joints
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n
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Hyaline Cartilage : Synchondrosis
Hyaline or fibrocartilage
Functionally two totally distinct entities
Hyaline cartilage – a growth mechanism
White fibrocartilage – partially movable
joints
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Growth mechanism
Between parts of a bone
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“Primary” and “secondary” cartilaginous joints :
Terms best avoided.
Symphysis
B
W
F
C
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Surfaces covered by hyaline cartilage
Thick plate of white fibrocartilage
Properties of white fibrocartilage
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Deformable
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Precursor of a synovial joint?
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Synovial Joints
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Evolution and development – secondary
cavitation
Midline symphyses – a coincidence?
The bones – articular surfaces
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“Freely movable”…? Freedom is relative!
More movable than any other type…
…almost
The tissue that unites…?
Some degree of movement – may be cumulative
Synovial Joints – Basic Features
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Union of bone
Fully explained next week
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n
Epiphyseal plate of cartilage
Growth and replacement by bone
Completion of growth – synostosis
Smooth… but not quite!
Articular cartilage
Fibrous capsule
Ligaments –
capsular or external
Synovial membrane
Synovial Joints – Articular Cartilage
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n
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Hyaline (WFC in membrane bones)
No perichondrium
Variable thickness
Nutrition…?
2
Synovial Joints – Capsule Etc
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Capsular attachment
Thickening of capsule : “Intrinsic” ligaments
Accessory ligaments
Areas of strength / weakness
Synovial Joints – Special Features
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Intra-articular discs
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Synovial Membrane & Fluid
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Membrane attachments
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Nature of synovial fluid
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Secretion and absorption
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Functional
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Degrees of freedom
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Viscosity
Synovial Joints – Subtypes
White Fibrocartilage
Reduce incongruity
n Modify (usually increase!)
range of movements
n Spread of synovial fluid –
reduce “drag”
Lining for the capsule
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n
Shapes of bony surfaces
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Incomplete discs
Menisci
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Other intra-articular structures
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Ligaments
Tendons
Synovial Joints – Bicondylar
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“Stability” – the anatomical concept
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Bony factors
Ligaments
Muscles
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Hinge
Saddle
Ball-and-socket
Plane
Condylar
Others
Stability and Movement
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Uniaxial, biaxial, multiaxial
Structural
The shoulder and the hip
A confusing term (and concept…?)
Two pairs of articular surfaces
Common capsule
The knee…
Temporomandibular joint
3
Around the Joints
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Bursa/e
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Bags of synovial membrane
Between tendons
Between tendon/muscle and joint capsule
Between muscle/tendon and bone
Between skin and bone
Nerves
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Joint sensations
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“Hilton’s Law”
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Capsule, ligaments, tendons, periosteum
Injury, pain and immobilisation
4