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Questions and Answers
Which muscles form the superior medial border of the popliteal fossa?
What shape is the popliteal fossa?
What is located on the floor of the popliteal fossa?
Which structure forms the inferior border of the popliteal fossa?
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What primarily covers the popliteal fossa?
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What is the primary function of the genicular arteries in the popliteal fossa?
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Which nerve primarily branches into the tibial nerve and common fibular nerve within the popliteal fossa?
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What anatomical structure creates the superior medial boundary of the popliteal fossa?
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Where does the lesser saphenous vein typically run in relation to other anatomical structures?
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What key feature is represented by the patellofemoral joint in the knee structure?
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What features of the patella help maintain its position within the patellofemoral joint?
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At approximately what degree of knee flexion does the patella primarily make contact with the superior facets?
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Which component of the knee joint is primarily described as a synovial joint with bicondylar properties?
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What is the Q-angle and how is it formed?
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What additional fiber structures contribute to the stabilization of the patella?
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Study Notes
Knee Joint - Surface Anatomy
- The patella and patellar tendon are visible from the anterior view.
- The lateral condyle of the femur and biceps tendon are visible and palpable from the lateral perspective.
- The semimembranosus and semitendinosus muscles are visible from the medial perspective.
- The popliteal fossa is a diamond-shaped space located at the posterior aspect of the knee, containing important neurovascular structures.
Popliteal Fossa - Boundaries
- Superior medial border: semitendinosus and semimembranosus muscles.
- Superior lateral border: distal component of biceps femoris and its tendon.
- Inferior border: medial and lateral heads of the gastrocnemius.
- Roof: fascia and skin.
- Floor: posterior surface of the femur, posterior aspect of the knee joint, and superior posterior aspect of the tibia.
Popliteal Fossa - Contents
- Sciatic nerve: descends from the posterior thigh and splits into the tibial nerve and the common fibular nerve.
- Tibial nerve: continues directly inferiorly.
- Common fibular nerve: peels off laterally.
- Sural nerve: branches off the sciatic nerve and provides sensory innervation to the posterior lateral calf.
- Popliteal artery and vein: continuation of the femoral artery and vein.
- Genicular arteries: supply blood to the knee joint.
- Popliteal artery: bifurcates into the anterior and posterior tibial arteries.
- Lesser saphenous vein: superficial vein ascending the posterior aspect of the leg, joining the popliteal vein in the popliteal fossa.
- Lymph nodes and bursa
Patellofemoral Joint - Surface Anatomy
- The patella is the most prominent structure of the patellofemoral joint, with the base being the more superficial component and the apex being the inferior component.
- The patellar ligament (or patellar tendon) connects the patella to the tibial tuberosity.
Patellofemoral Joint - Articular Surfaces
- The patella has multiple ridges creating articular surfaces: inferior facets, middle facets, superior facets, and a medial facet.
- The patellar surface of the femur is a groove between the medial and lateral condyles.
- Different facets of the patella contact the femur at different ranges of knee flexion.
Patellofemoral Joint - Reinforcement
- Bony congruence: the shape of the groove on the femur and the wedge shape of the patella contribute to stability.
- Quadriceps tendon and patellar tendon: reinforce the patella vertically.
- Retinacula: tendinous fibers from vastus lateralis, vastus medialis, and the iliotibial band provide additional stabilization.
Q-Angle
- The Q-angle is the angle between two lines: one from the ASIS to the center of the patella, and the other from the center of the patella to the tibial tuberosity.
- It represents the valgus angle of the knee joint.
- It varies greatly based on individual bony structure and may be linked to certain pathologies.
- A dynamic Q-angle relates to control at the hip and knee joints.
Tibiofemoral Joint - Structure
- Bony structures: medial and lateral femoral condyles, intercondylar fossa, medial and lateral tibial condyles, intercondylar ridge.
- Joint capsule: a connective tissue bag encircling the knee joint, reinforced by ligaments and retinacula.
- Synovium: lines the joint capsule and folds inward around the cruciate ligaments.
- Bursae: fluid-filled sacs located in areas of potential friction.
Tibiofemoral Joint - Capsule
- The joint capsule attaches to the distal femur and the superior tibia.
- Anteriorly: the capsule is deficient due to the patella.
- Posteriorly: the capsule has an opening for the popliteus tendon.
Tibiofemoral Joint - Synovium
- In the knee, the synovium folds inward, creating plicae, which extend into the intercondylar fossa.
- This unique structure is a result of the development of the knee joint from two separate joint capsules in fetal development.
Knee Joint Movements - Osteokinematics and Arthrokinematics
- Knee joint movement is classified into two categories: Osteokinematics and Arthrokinematics
- Osteokinematics is the movement of the bones/entire joint (e.g. flexion, extension, rotation)
- Arthrokinematics is the movement of joint surfaces on each other
- Primary osteokinematics of the knee include flexion and extension
- Quadriceps are the primary knee extensors
- Hamstrings are the primary knee flexors
- A slight rotation of the tibia on the femur is possible at 90 degrees of knee flexion
- Biceps Femoris assists in lateral rotation of the tibia
- Semitendinosus and Semimembranosus assist in medial rotation of the tibia
- Arthrokinematics of the knee involve rolling and sliding of the femoral condyles on the tibial condyles.
- During knee flexion, the femoral condyles roll posteriorly and slide anteriorly
- This roll and slide movement prevents the femur from falling off the back of the tibia
- Understanding the concave and convex surfaces of joints is essential for clinicians
- The knee can be locked by lateral rotation of the tibia
- Locking of the knee occurs during the final 20-30 degrees of extension
- The tibial tuberosity can be palpated during this movement
Blood Supply of the Knee
- The anterior tibial artery provides blood supply to the knee joint
- The posterior tibial artery also contributes to the blood supply
Clinical Considerations of the Knee:
- Understanding the anatomy of the knee is crucial for clinical practice
- Knee injuries (e.g. ACL, PCL tears, meniscus tears) are common
- Knowledge of the joint motion and stability is vital for treatment and rehabilitation
Knee Joint Function and Stability
- Locking the knee is crucial for stability while standing.
- Full extension is essential for efficient upright stance.
- Insufficient knee extension leads to increased muscle fatigue and strain.
Knee Blood Supply
- The primary blood supply to the knee comes from the popliteal artery through the genicular branches.
- Anastomoses create a network of blood vessels, providing redundancy in case of arterial blockage.
- Additional blood supply comes from descending branches of the femoral artery and a recurrent branch from the anterior tibial artery.
Common Knee Injuries
- Torn cruciate ligaments (ACL more common than PCL).
- Torn menisci, with varying severity and surgical interventions.
- Torn collateral ligaments (medial more common than lateral).
- Patellofemoral syndrome, a common condition with various management strategies.
- Tendinosis and tendinitis, such as patellar tendinitis often associated with increased physical activity.
- Degenerative joint disease (DJD) or arthritis.
- Post-operative rehabilitation following total knee replacement.
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Description
Test your knowledge on the surface anatomy of the knee joint, including the patella, condyles, and important structures of the popliteal fossa. This quiz covers boundaries, contents, and key muscle associations of the knee. Perfect for students of anatomy or sports medicine.
