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Skeletal System (Articulation) (Joints (Three functional categories…
Skeletal System (Articulation)
Joints
Where two bones interconect
Where one bone joins cartilage
Without joints, no movement
Bones are not flexible
Reflect compromise between need for strength and mobility
Anatomical structure for each joint creates exact movement possible
Range of motion
Different joints for various movements
Three functional categories
Synarthrosis
No movement
Skull, sternum, ribs
Amphiarthrosis
Little movement
Tibia, fibula
Diarthrosis
Free movement
Shoulder, knee
Complex in structure
Greatest range of motion
Not as strong
Synarthrotic & amphiarthrotic
Simple structure
Strong
Direct connection between bones
Synovial joints
Components
Articular cartilages in epiphysis
Hyaline cartilages
Matrix contains more water
No perichondrium
Smooth & slick - reduce friction
Separated by thin film called synovial fluid
Similar to loose connective tissue ground substance
Produced at synovial membrane
Circulates areolar tissue to join cavity
Moves through articular cartilages (center of joint)
Less than 3 mL
Functions
Lubrication
Nutrient distribution
Shock absorption
Joint capsule
Dense & fibrous
May be reinforced with accessory structures (tendons & ligaments)
Accessory structures
Support & stability
Not in every joint
Most are in knee
Tendons & quadriceps
Passes across joint to limit movement for mechanical support
Bursa (pouch)
Small pocket filled with synovial fluid
Formed in areas where tendons and ligaments rub against other tissues
Shock absorbents
Fat pads
Adipose tissue cover by synovial membrane
Protects articular cartilages
Acts as packing material for joints
Meniscus (crescent shape)
Fibrous cartilage between bones of synovial joints
Subdivide cavity, allow fluid flow, allow variation of shapes of articular surfaces
Protection of bone rubbing on bone
Ligaments
Strengthen, support, & reinforce joints
Made of dense regular connective tissue
Intrinsic ligaments
Localized thickening joint capsule
Extrinsic ligaments
Separate from joint capsule
May pass inside of outside joint capsule
Continuous with pariosteum in each bone
Selected angular movements
Flexion and extension
Applied to movements of long bone of skin
Axial skeleton
Flexion
Anterior and posterior movement
Reduces angle between articulating elements
Ex - flex muscles
Lateral flexion
Vertebral column ending to the side
Dorsiflexion
Ankle joint and elevation of sole
Plantar flexion
Extension at ankle joint and elevation of heel
Extension
Anterior or posterior movement
Increases angle between articulating elements
Hyperextention
When you extend past anatomical position
Abduction and adduction
Abduction
Movement away from body longitudinal axis in frontal plane
Adduction
Movement towards body longitudinal axis in frontal plane
Circumduction
Moving arm or thigh drawing big circle at distal end of limb
Joints (cont.)
Shoulder joint
Greatest ROM of all joints
Frequently dislocated joint
Stability provided by skeletal muscles
Ball and socket joint
Formed by head of humerus and glenoid cavity of scapula
Ligaments that stabilize the shoulder
Coracolavicular
Acromioclavicular
Coraco-acromial
Coracohumeral
Glenohumeral
Knee joint
Three separate articulations
Medial condyle of tibia to medial condyle of femur
Femur
Tibula
Fibula
Lateral condyle of tibia to lateral condyle of femur
Patella and patellar surface of femur
External support
Quadriceps tendon to patella
Patellar ligament to anterior tibia
Fibular collateral ligament
Lateral support
Tibial collateral ligament
Medial support
Popliteal ligaments
Posterior support extending between femur and heads of fibula and tibia
Tendons of several muscles attach to femur and tibia
Internal support
Circulate ligaments limit posterior and anterior movements of femur and maintain alignment of condyles
ACL - at full extension, knees become locked
Due to sideways movement of knee
Opposite movement to unlock this
Medial and lateral menisci
Fibrous cartilage make it stronger
Acts as cushions and provides lateral stability to joints