Lecture 11: Knee And Popliteal Fossa Flashcards
This is a modified hinge joint with femoral condyle and tibial plateaus as its articulating surfaces. A. Tibiofemoral joint B. Patellofemoral joint C. Talotibial joint D. Subtalar joint
Ans: A
Tibiofemoral (Knee) Joint
Modified hinge joint
Articulating surfaces: • Femoral condyles: • Convex and asymmetric • Medial condyle is larger than the lateral. • Condyles are separated anteriorly by patellar surface: Asymmetric, shallow, saddle-shaped groove • Condyles are separated posteriorly by intercondylar fossa.
• Tibial plateaus: • Concave and asymmetric • Articular surface of medial plateau is 50% larger than that of lateral. • Separated by intercondylar tubercles
This ligament is not attached to the meniscus A. Coronary ligament B. Anterior transverse ligament C. Lateral collateral ligament D. Cruciate ligaments
Ans: C
Meniscus has
Coronary ligament and anterior transverse ligaments, posterior cruciate ligament, medial (tibial) collateral ligament
lateral (fibular) collarteral ligament is separated from the lateral meniscus by popliteal tendon
This is a characteristic of the menisci: A. Highly vascularized B. Heal well C. Wedge shaped cartilaginous disc D. No loss of knee function when menisci are removed
Ans: D
Menisci characteristic
Wedge-shaped fibrocartilaginous joint discs: • Poorly vascularized • Do not heal well • No loss of knee function when menisci are removed
This is more often injured, larger of the two meniscus and is more securely attached. A. Patella B. Joint capsule C. Medial meniscus D. Lateral meniscus
Ans : C
Medial meniscus: Larger of the two • More securely attached • Also attached to medial collateral ligament and to semimembranosus muscle • Therefore, more often injured than lateral
Lateral meniscus: • Attached to posterior cruciate ligament: Via meniscofemoral ligament • Attached to popliteus muscle
Medial meniscus drawn forward during extension:
A. Due to tension in semi membranosus muscle
B. Due to tension in anterior capsular fibers
C. Drawn by tension in popliteal expansion
D. Due to the distortion of the medial meniscus
Ans : B
Movement:
• Medial meniscus moves posteriorly during flexion: Due to tension in semi membranosus muscle • Medial meniscus drawn forward during extension: Due to tension in anterior capsular fibers • Lateral meniscus moves posteriorly during flexion: Drawn by tension in popliteal expansion, Distorts more than medial meniscus
Joint capsule excludes:
A. Posterior cruciate ligament
B. Quadriceps tendon
C. Popliteal tendon
Ans: A
Joint Capsule
Large and lax Deficient on lateral condyle: For passage of popliteal tendon Anterior wall replaced by quadriceps tendon Excludes cruciate ligaments Commonly communicates with synovial bursae
This lies between patellar ligament and tibia and may become inflamed as a result of excessive kneeling A. Grastrocnemius B. Deep infrapatellar C. Suprapatellar D. Prepatellar
Suprapatellar: Upward expansion of synovial cavity between femur and quadriceps muscle and tendon and proximally receives insertion of articularis genus muscle
Prepatellar: Lies between superficial surface of patella and skin
Deep Infrapatellar: Lies between patellar ligament and tibia and may become inflamed as a result of excessive kneeling
Subpopliteal: Located btwn tendon of popliteus muscle and lateral condyle of tibia
Gastrocnemius: Under medial head of gastrocnemius
Anserine bursa: btwn pes anserinus and tibial collateral ligament Note: pes anserinu s = combined tendons of semitendinosus, gracilis, and sartorius.
Weakest of cruciates ligaments that is slack during flexion and taut during extension, prevents backward sliding of femur on tibia and prevents hyperextension of knee A. Tibial collateral B. Lateral collateral C. Posterior cruciate D. Anterior cruciate
Ans: D
Ligaments
Collaterals:
Medial (tibial): •Attachments: Medial femoral condyle, Proximal tibia •Partly continuous w/ adductor magnus tendon •Attached to medial meniscus •Distally separated from tibia by genicular vessels and nerves
Lateral (fibular): •Splits tendon of biceps femoris muscle •Separated from lateral meniscus by popliteal tendon
Anterior cruciate: •Weakest of cruciates •Slack during flexion & taut during extension •Prevents backward sliding of femur on tibia •Prevents hyperextension of knee
Posterior cruciate: •Taut during flexion & slack during extension •Prevents forward sliding of femur on tibia •Prevents hyperflexion of knee.
During the lateral- medial rotation of the tibia, when there is more that 90 degrees of flexion then there
A. It allows the anterior sliding of femoral condyle on tibial plateau
B. Femoral condyle roll anteriorly and slide posteriorly
C. Medial and lateral rotation of the ROM decreases
D. There is a rolling and spinning of the condyles
Ans C
Movements
Flexion: • First part (0 to 25 degrees): Posterior rolling and spinning • Anterior sliding of femoral condyles on tibial plateaus
Extension: • First part: Femoral condyles roll anteriorly and slide posteriorly. • Followed by rolling and spinning of condyles
Lateral-medial rotation of tibia: • At 90 degrees of knee flexion: Up to 40 degrees of lateral rotation, Up to 30 degrees of medial rotation • Greater than 90 degrees of flexion: Medial and lateral rotation ROM decreases
Which is true of the patella?
A. It is attached to teh quadriceps via the quadriceps tendon and the tibial tuberosity via ligamentum patella
B. It is not embedded in the joint capsule
C. Ligamentum patella pulls patella distally and anteriorly
D. Patella is pulled proximally by tibia
Ans A
Patellofemoral Joint
Patella is embedded in the joint capsule. It is attached to the quadriceps via the quadriceps tendon and to the tibial tuberosity via the ligamentum patellae. During knee flexion/extension: • Central ridge of patella slides along central groove of femur During flexion: • Tibia moves posteriorly • Ligamentum patellae pulls patella distally and posteriorly: Causes patella to remain firmly in apposition to femur During extension: • Patella is pulled proximally by quadriceps • Vastus lateralis tends to pull patella laterally • Vastus medialis oblique counteracts vastus lateralis. Q-angle: • Formed by vector of quadriceps: From ASIS to middle of patella • And vector of pull of ligamentum patellae: From tibial tubercle to middle of patella • 15 degrees
Which muscle helps unlock the knee at the beginning of knee flexion? A. Semitendinosus B. Quadriceps C. Gastrocnemius D. Popliteal
Ans D.
Locking at Full Extension
During final few degrees of extension: • Femur rotates medially on tibia. (Note that tibia would also rotate laterally on femur.) • Knee is brought into close-packed position: Tibial tubercles are lodged in intercondylar notch. Menisci are tightly interposed between tibial and femoral condyles. = Locked or screw-home mechanism Popliteus laterally rotates femur for unlocking at beginning of knee flexion
What is the inferior boundary of the popliteal fossa?
A. Medial and lateral heads of the gastrocnemius
B. Semimembtanosus
C. Semitendinosus
D. Popliteus
Ans A
Popliteal Fossa
The popliteal fossa is the posterior aspect of the knee. • It is a deep recess formed by the borders of four muscles.
Bony landmarks: Popliteal surface of femur (floor)
Boundaries: •Superior: Semimembranosus and semitendinosus
•Inferior: Medial and lateral heads of the gastrocnemius
Contents: • Fat • Several popliteal lymph nodes • Popliteal bursa • Superficial to deep: Tibial nerve Popliteal vein Popliteal artery • Common peroneal (fibular) nerve • Small saphenous vein
What is true of the popliteal artery? A. Continuation of the sciatic artery B. Begins at adductor hiatus C. Begins at the popliteal muscle D. Divides into anterior and posterior fibular artery
Ans: B
- Popliteal artery: • Continuation of femoral artery • Begins at adductor hiatus • Ends at lower border of popliteus muscle • Gives off five genicular branches: Lateral and medial superior geniculars Lateral and medial inferior geniculars Middle genicular • Divides into anterior and posterior tibial arteries
- Popliteal vein: • Formed from venae comitantes of anterior and posterior tibial arteries • Receives lesser (small) saphenous vein • Becomes femoral vein at adductor hiatus
This nerve supplies the posterior thigh and leg A. Common peroneal nerve B. Tibial nerve C. Sural nerve D. Deep peroneal nerves
Ans: B
• Tibial nerve: • Part of sciatic nerve • Supplies posterior thigh and leg
• Common peroneal (fibular) nerve: • Part of sciatic nerve • Branches into superficial and deep peroneal (fibular) nerves • Supplies lateral and anterior leg
Sural nerve: • Arises via: • Communicating branch from tibial nerve • Communicating branch from common peroneal (fibular) nerve
Circumflex comes of which artery? A. Femoral artery B. Descending genicular artery C. Anterior tibial D. Posterior tibial
Ans C
Genicular anastomosis:
• Descending genicular: From femoral artery
• Descending branch of lateral femoral circumflex
•Genicular branches of popliteal artery: Medial superior/inferior genicular, Lateral superior/inferior genicular, Middle genicular (continuation of the femoral artery?)
• Branches of anterior tibial: Circumflex fibular, Anterior tibial recurrent
• Branches of posterior tibial:Posterior tibial recurrent
