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Knee joint

Bones: Femur Tibia Fibula Patella Movements: Extension – Quadriceps Flexion - Hamstrings Articulations: Tibiofemoral Patellofemoral. Which plane is this movement in?. Knee joint. Terms of position and direction. How much force is across your knee joint when going up or down stairs?.

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Knee joint

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  1. Bones: Femur Tibia Fibula Patella Movements: Extension – Quadriceps Flexion - Hamstrings Articulations: Tibiofemoral Patellofemoral Which plane is this movement in? Knee joint

  2. Terms of position and direction

  3. How much force is across your knee joint when going up or down stairs? Answer: 4-6 times your body weight Adult 200 lbs More than 1000 lbs!!!

  4. Where does that force come from? Why don’t you seem to feel it? What prevents your knee from buckling and collapsing?

  5. Introduction to Ligaments and Tendons • Ligaments (connect bone to bone) and tendons (connect muscle to bone) are dense connective tissues • Largely comprised of collagen • Consist of relatively few cells (fibroblasts) (20%) and an abundant extracellular matrix (ECM) (80%)

  6. Ligament and Tendon Structure Cells that produce collagen which make up the ligament or tendon

  7. Ligament and Tendon Structure • Fibril level • We see something called crimp • Waviness of the fibril • Structural characteristic that plays a significant role in mechanics of tendon/ligament • Contributes to non-linear stress-strain relationship of tendon/ligament

  8. Tendon Anatomy Contains collagen fibrils (Type I) Contains proteoglycan matrix (attracts water into tissue) Contains fibroblasts arranged in parallel rows Tendon Functions Carry tensile forces from muscles to bone Carry compressive forces when wrapped around bone like a pulley Ligament and Tendon Structure

  9. Ligament Anatomy Collagen fibrils slightly less organized that tendon Higher % of proteoglycan matrix than tendon Contains fibroblasts Ligament Functions Carry tensile forces from bone to bone Carry compressive forces when wrapped around bone like a pulley Ligament and Tendon Structure

  10. FEMUR ACL PCL MCL LCL TIBIA FIBULA Knee Ligaments

  11. Quadriceps Tendon Patellar Patellar Tendon

  12. Gross/Collagen Microstructure MCL

  13. Femoral Insertion Tibial Insertion: Mature deep fibers bone bone mineralized fibrocartilage superficial fibers fibro- cartilage ligament connects to periosteum Insertions to Bone

  14. Ligament Substance Collagens (75-80% Dry Weight) • Type I - tensile strength • Type III - scar • Type V - regulation of collagen fiber diameter Linsenmayer, et al., 1993 • Type XII - “lubrication” between collagen fibers Niyibizi, et al., 1995

  15. • Type XIV - minimize shear stresses between collagen fibrils at soft tissue-hard tissue interface Insertions to Bone Collagens • Type X - insertion site, mineralized fibrocartilagenous zone Niyibizi, et al., 1996

  16. Knee joint • Major muscles • Sartorius • Quadriceps • rectus femoris • vastis intermedius • vastis medialis • vastis lateralis

  17. Knee joint • Major muscles - movements

  18. Knee joint • Major muscles • Hamstrings • Semitendinosis • biceps femoris • gracilis

  19. Introduction to Muscle Tissue • Three types of muscle • Skeletal • Voluntary and striated • Cardiac • Involuntary, striated, and autorhythmic • Smooth • Involuntary and non-striated

  20. Function of Muscle • Motion • Movement of body fluids • Regulation of body fluids (e.g. bladder) • Body stability • Heat production

  21. Muscle Characteristics • Excitability • Action potentials • Contraction • Generate force • Extensibility • Stretchable • Elasticity

  22. Muscle Anatomy: Connective Tissues • Superficial fascia • Connective and adipose tissue • Storage, insulation, and protection • Deep fascia • Epimysium • Whole muscle • Perimysium • Bundles of fibers • Endomysium • Single muscle fiber

  23. Composition and Structure • Epimysium covers the muscle (fascia) • Muscle is composed of many bundles of muscle fibers called fascicles • Fascicles are covered by perimysium

  24. Composition and Structure • Each muscle fiber is covered by endomysium

  25. Composition and Structure • Each muscle fiber is composed of numerous myofibrils • Myofibrils are the contractile elements of muscle • The functional unit is the sarcomere

  26. Muscle Contraction

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