Download Joints

Articular System (Joints)
ANHB 2212 – 2007
Avinash Bharadwaj
Joints
 “Articulation”
 Articulatio / Arthron  Arthrology
 Where two or more bones or
parts of bones unite…
 How they are joined together…
the tissues that unite bones
Joint Classification
 Structural
 The tissues that unite bones
 Functional
 Mobility or otherwise
 Synovial joints – axes of movements
 No perfect system (Explained as we go!)
 Arbitrary and confusing terms
 Overlapping terminology
 Latin terminology and anglicised versions
 The choice is yours!
Tissues Uniting Bones
 Fibrous tissue
 Unossified tissue between membrane bones
(Explained fully next week!)
 Ligaments (Dense connective tissue!)
 Cartilage
 Hyaline cartilage
 White fibrocartilage
 Fibrous capsule with a cavity
 Special features for lubrication, movement and stability
Movable Joints
 “Movability” (mobility…?) is a relative term!
 Movement is always associated with restrictions
 Active movements – by muscles
 Movements due to other factors
 Shapes of bony surfaces
 Tensions in ligaments
 Other external factors (pelvic joints in childbirth)
 Passive movements in clinical examination
Fibrous Joints
 Sutures (“stitches”)
 Between flat bones of the skull
Surface view
Section (Magnified!)
Periosteum
Bone
Fibrous Joints
R
 Syndesmoses
 Inferior tibiofibular joint
(Not shown here)
 Interosseous membranes
 Separation of compartments
 Additional areas for muscle
attachments
 Some other ligaments…
 Gomphoses
 Tooth and bone
 “Peg-and-socket”
U
Cartilaginous Joints
 Synchondrosis – Hyaline cartilage
 Growth mechanism  synostosis
 Between primary and secondary centres
 Between named bones (e.g. sphenoid + occipital)
(Week 12 Histology!)
 Symphysis – White fibrocartilage
 WFC is deformable
 Partially movable joints
 Occasional cavities – ? Evolution of synovial joints
Primary and secondary cartilaginous joints : terms best avoided.
Functionally two distinct entities.
Cartilaginous Joints
Synovial Joints
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“Freely movable”…?
Freedom is relative!
More movable than any other type…!
Fibrous tissue bond, with a cavity
Synovial Joints – Basic Features
 The bones – articular surfaces
 Smooth… but not quite!
 Articular cartilage
 Fibrous capsule
 Ligaments
 Capsular thickening
 External
 Synovial membrane
Synovial Joints – Articular Cartilage
 Hyaline (WFC in membrane bones)
 No perichondrium
 Variable thickness
 Depends on the type of joint
 In curved surfaces
 Convex – thick in the centre
 Concave – thin in the centre
Synovial Joints – Capsule Etc
 Capsular attachment
 Thickening of capsule : “Intrinsic” ligaments
 Areas of strength / weakness
 Capsule may be loose in places
 Other ligaments (“extracapsular”)
 Synovial membrane and fluid
Intra-articular discs
 White Fibrocartilage
 Reduce incongruity
 Modify movements
 Spread of synovial fluid –
reduce “drag”
 Incomplete discs / menisci
Other Intra-articular Structures
 Ligaments
 Cruciate ligaments – knee joint
 Tendons
 Long head of biceps – shoulder joint
 Popliteus – knee joint
 Fat pads
 Such structures are covered by synovial
membrane.
Synovial Joints – Subtypes
 Functional
 Degrees of freedom
 Uniaxial, biaxial, multiaxial
 Structural
 Shapes of bony surfaces
Synovial Joints – Subtypes
 Plane : Sliding movements
(“Non-axial joint”)
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Hinge : Uniaxial (e.g. elbow)
Ball-and-socket : Multiaxial (Shoulder, hip)
Saddle : Two planes of movement + combinations
Bicondylar : Two pairs of surfaces
Pivot : Osseofibrous ring + rotating bone
Nothing is perfect – do not expect geometrical shapes!
Two Types Illustrated
Pivot joint –
Osseofibrous ring and
head of radius.
Bicondylar joint – Knee
Two pairs of articular surfaces
Bursae
 Muscles / tendons in close proximity – friction
 Bursa (Latin for purse!)
 Thin walled connective tissue bag
 Lining of synovial membrane
 Between joint capsule and tendon / muscle,
bone and tendon / muscle, or between
muscles / tendons.
 Bursitis – painful
 Some bursae communicate with joint cavity
Joint Stability
 Movement and stability – a compromise
 Factors in stability
 Bony configuration
 Capsule and ligaments
 Tendons and muscles
 Sometimes blend with capsule – rotator cuff
Nerves
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Rich sensory innervation
Capsule, ligaments, periosteum
Same nerves as those that supply muscles
Joint pain
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Bony injuries
Capsular / ligamentous injuries
Synovial membrane
And more…
Blood Vessels
 Rich blood supply
 All parts except cartilages
 Articular cartilage
 By diffusion through synovial fluid
 Blood vessels of surrounding areas (capsule,
bone)
Last Slide