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Three basic principles in determinding joint structure and function
Joint design, structure & function
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Joint design
determined by the funtion of the joint and its component parts
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Joint structure
Determines the joint's function
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Single vs. Complex function joints
- Single- creates stability (cranium sutures)
- Complex- creates mobility (hip)
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How many bones are in the Human body?
208
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Joint Categories (classification of Joints)
Synarthroses & diarthroses joints
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Synarthroses (non-synovial) Joints
Made up of 2 types of connective tissue w/ no synovial fluid & no synovial membrane
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Fibrous Joints
- bone--solid connective tissue--bone
- -Fibrous connective tissue
- a) suture joint
- b) gomphosis joint
- c) syndemosis
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Suture Joint
only example- coronal sutures in the human skull
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Gomphosis Joint
- Peg in a hole
- (ex) tooth is inserted in the bony socket of the mandible
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Syndemosis Joint
- Two bony components are joined directly by a ligament, cord, or aponeurotic membrane.
- (ex) shaft of the fibula and tibia (held by aponeurotic membrane)
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Diarthrosis Joint
(ex) Cartilagenous Joint
- -Joint Capsule
- -Joint Cavity
- -Synovial membrane
- -Synovial Fluid
- -Hyaline cartilage
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Cartilagenous Joint
bone--cartilage--bone
The cartilage material here is fibrocartilage or hyaline growth cartilage
- -Symphysis Joint
- -Synchondrosis
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Symphysis Joint
- Fibrocartilage Material
- (ex) symphysis pubis joint (forms the 2 sides of the pelvis)
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Synchondrosis Joint
-most clinically used in diarthrosis category
- Hyaline Growth Cartilage in the developing skeletal system-- When the individual reaches maturity, the hyaline cartilage ossifies and converts to a bony union
- (ex) first sternalcostal joint
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Joint Capsule
encapsulates the entire joint structure, made of fibrous tissue (stratum fibrosum)
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Joint Cavity
- enclosed by the entire joint capsule
- -needed for articulation (bone on bone)
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Synovial Membrane
lines the inner surface of the capsule (stratum synovium)-- creates synovial fluid
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Synovial Fluid
Forms a film over the joint surface
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Hyaline Cartilage
- Covers the joint surface (articular cartilage)
- --also found on the ends of long bones
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Subclassification of Synovial Joints
- -Uniaxial Joints
- -Biaxial Joints
- -Triaxial Joints
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Uniaxial Joints
One plane/axis of movement/ one degree of freedom
- -Hinge Joints
- -Pivot Joints
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Hinge Joints
- Sagittal plane/frontal axis
- Flexion/extension movement
(ex) IP Joints of the hands
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Biaxial Joints
Two planes/axis of movement/ two degrees of freedom
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Motion & Planes of Biaxial Joints
- -frontal plane/a-p axis
- -sagittal plane/frontal axis
- -Flexion & Extension
- -Abduction & Adduction
- (Ex) Metacarpal Joints- knuckles of the hand & Saddle Joint of the thumb
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Triaxial Joints
Three planes/axis of movement or three degrees of freedom
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Motion & Planes of Triaxial Joints
- -Transverse plane/longitudinal axis
- -frontal plane/a-p axis
- -sagittal plane/frontal axis
- -flexion/extension
- -abduction/adduction
- -internal/external rotation
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Stratum Fibrosum
- Outer Layer of the Joint Capsule
- -Poorly vascularized, richly innervated w/ joint receptors (not a lot of blood vessels, but many feedback receptors-- tells brain where joints are in relation to space)
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Stratum Synovium
- Inner layer of the Joint Capsule
- -highly vascularized but poorly innervated
- -Entry point of nutrients into the synovial fluid & exit point for waste products
- -Helps produce synovial fluid
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Synovial Fluid
- Compound of Hyaluronate & Lubricin
- -Creates fluid viscosity
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Factors which affect the viscosity of synovial fluid
- Increased speed in the Joint=decreased viscosisty w/ least amout of joint resistance to movement
- Increased temperature=decreased viscosity
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Joint Lubrication Theories
- -Boundary Lubrication
- -Fluid Lubrication
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Boundary Lubrication
Each weight bearing surface is coated w/ a thin layer of molecules which keeps the opposing surfaces from toucing each other--lubricin adheres to the artiular surfaes
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Fluid Lubrication
Articular cartilage releases fluid when hydrosttic pressure increases in weight bearing joints, fluid stops when pressure decreases
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Arthrokinematics
the study of movement of the joint surfaces (articular surfaces) and their interaction w/ each other
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3 Definitions of Movement
- -Rolling
- -Sliding
- -Spinning
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Rolling Movement
- Like a tire rolling on the road
- (ex) knee joint
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Sliding Movement
- Translation--like gliding one component over another
- (ex) the TMJ joint, knuckles of the hand
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Spinning Movement
- Like a toy top spinning
- (ex) superior radio-ulnar joint--the head of the radius spins on the capitulum of the humerus
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Curvilinear Movement
Combination of spinning & rolling
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MOVEMENT IS DEPENDANT UPON...
SURFACES OF THE JOINT STRUCTURE
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TWO JOINT SURFACES RESULT IN...
- TWO MOVEMENT PATTERNS
- -Ovoid Joint
- -Sellar Joint
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Ovoid Joint
- -One surface is concave, the other is convex
- -Articulating surface of th bone moves in opposite direction of the moving bone
- (ex) abduction of shoulder bone (humerus)
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Sellar Joint
- -Joint surface is convex & concave
- -Articulating surface of the bone moves in the same direction as the moving bone
- (ex) knee joint
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Osteokinematics
- movement of bones rather than the movement of articulating surfaces (more important clinically)
- **Use ROM when identifying the movement of the bones
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Range of Motion (ROM)
range which is available to a joint w/in the anatomical limits of the joint
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Determining factors of anatomical limits
- - shape of the joint surface
- - the joint capsule
- - ligaments
- - muscle bulk
- - surrounding structures
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Hypermobility
Increased/accessive ROM
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Contracture
- Fixed joint=no more functional movement
- --more common w/ flexors/extensors
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Living Material Used in making Human Joints
- CONNECTIVE TISSUE
- -ligaments, tendons, bursae, cartilage, disks, plates, menisci, fat pads, ect.
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Connective Tissue
- Composed of
- -Cellular Component & Extracellular Matrix
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Cellular Component of Connective Tissue
- -Produce/maintain extracellular matrix
- -Antibodies fight infection
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Extracellular Matrix
- a) Non-Fibrous component/ground substance
- b) Fibrous Component
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Non-Fibrous component/ ground substance
- -Binds water & provides support
- -Maintains hydration w/in the tissue w/ protiens (glycoprotein/proteoglycans)
**glycoproteins affect extracellular matrix which affects stability
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Fibrous Component
- Support framework w/
- 1) collagen=strength
- 2) elastin=elasticity
~flexibilty & support
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