Lecture 20 Outline of Last Lecture I Pelvic Girdle II Differences Between Male-Female Pelvis III Pelvic Girdle During Pregnancy IV Pelvic Girdle Joints V Ligaments VI Pelvic Girdle Functions VII Movements VIII Role of Pelvis During Walking IX Spinal Misalignments X Effects of Backrest XI Muscles that Move to the Pelvic Girdle XII Rectus Abdominis XIII External/Internal Obliques XIV Erector Spinae Muscle XV Quadratus Lumborum XVI Hip Muscles XVII Anterior/Posterior Rotation Outline of Current Lecture I. The Knee Joint II. Bones III. Knee Joint-Stability IV. Joints V. Osteoarthritis VI. Ligaments VII. Menisci VIII. Joint Support HPER 205 1st Edition These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best !used as a supplement to your own notes, not as a substitute. !IX. Joint Movements X. Screw Home Mechanism XI. Q Angle XII. Loads on the Knee XIII. Patellofemoral Joint Loads XIV. Muscles XV. Popliteus XVI. Gastrocnemius Current Lecture A. The Knee Joint1. Largest synovial joint in the body2. Very vulnerable to injurya. very large loadsb. between two long lever armsB. Bones1. Femoral condyles articulate on tibial plateaus2. Tibia — mediala. larger of the two bones3. Fibula — laterala. serves as the attachment for knee joint structuresb. doesn't articulate with femur or patella4. Patellaa. sesamoid boneb. imbedded in quadriceps tendon/patellar ligamentc. serves as a pulleyC. Knee Joint-Stability1. Poor joint cavity: unstable2. Excellent ligament support: static3. Excellent muscle support: dynamic stability D. Joints1. Knee joint (tibiofemoral joint)a. classified as a ___ joint- varus & valgus movement- internal/external rotationb. ____ articulations —one for each condyle2. Patellofemoral jointa. gliding joint3. Proximal tibiofibular jointa. not much movement4. Ligaments provide static stability5. Quadriceps and hamstrings produce dynamic stability6. Articular cartilage surfaces on femur and tibia7. Menisci form cushions between bonesa. attached to tibia- deepen cavity- enhance stabilityE. Osteoarthritis1. More on medial side2. > 20 million americans F. Ligaments1. Anterior and posterior cruciate ligaments (ACL and PCL)a. cross within the jointb. ACL prevents anterior movement of tibia, rotation, & hyperextensionc. PCL prevents posterior movement of tibia2. Fibular (lateral) collateral ligament (LCL)a. maintains lateral stability by resting various forcesb. infrequently injured3. Tibial (medial) collateral ligament (MCL)a. maintains medial stability by resting values forcesb. commonly injuredG. Menisci1. Fibrocartilage discs2. Semilunar shape3. Deepen joint cavity (stability)4. Shock absorption5. Load distribution6. Thicker on outside border and thin on inside border7. Medial mensicus — larger and more open C appearance8. Lateral meniscus — closed C configuration9. Injury may occur due to significant compression and shear forces during rotationH. Joint Support1. Synodal cavitya. supplies knee with synovial fluid2. Infrapatellar fat pada. just posterior to patellar tendon3. Iliotibial banda. band of connective tissueb. provides lateral stabilityc. IT band syndrome4. Bursaea. more than 10 bursa in and around kneeb. they absorb shock or prevent frictionc. can become inflamed demo direct trauma to the knee or overuse such as prolonged kneeling I. Joint Movements1. Extends to 180 degrees2. Hyperextension ~ 10 degrees3. Flexion to about 140 degrees4. With knee flexed 30 degrees or morea. internal rotation 30 degreesb. external rotation 45 degreesJ. Screw Home Mechanism1. Knee “screws home” to fully extenda. due to the shape of medial femoral condyle2. During full extension tibia externally rotates ~ 10 degrees to achieve proper alignment of joint3. During initial flexion from full extension knee “unlocks” by tibia rotating internallyK. Q Angle1. Line of pull for quadriceps tendona. ASIS to patella2. Line of pull to patella ligamenta. patella to tibial tuberosityb. angle formed = Q angle3. ~ 15 degrees or less for males4. ~ 20 degrees or less in females5. Higher Q angles increase potential knee problems6. Strength & endurance in vastus medialis counteracts lateral pull of vastus lateralisL. Loads on the Knee1. Mostly compressive and shear2. Compressive loads increase with muscular contraction3. Normal walking gait > 3BWM. Patellofemoral Joint Loads1. Patellar tracking2. More common in women3. Affected by Q angle4. Patellofemorala. ~ 1/2 BW walkingb. > 3BW stair climbingc. > 7 BW squatsN. Muscles1. Quadriceps muscle groupa. rectus femoris, vastus medialis, vastus intermedius, vastus lateralis- all attach to patella via quadriceps tendon — then to tibial tuberosity via patellar ligament2. Hamstring muscle groupa. responsible for knee flexionb, consists of 3 muscles- semitendinosus (medial int rot)- semimembranosis (medial int rot)- biceps femoris (lateral ext rot)O. Popliteus1. Origin: lateral condyle of femur2. Insertion: tibia3. Actions: flexes knee, medial rotationP. Gastrocnemius1. Origin: condyles of femur2. Insertion: calcaneus3. Actions: flexes knee, plantar flexes ankleQ. Knee Extension1. Muscles: quads2. Normally 25-30% stronger than flexorsR. Knee Flexors1. Muscles: hamstrings2. Antagonist to quadsa. deceleration of lower