Anatomy II Lecture 11: Knee and Popliteal Fossa Flashcards
What are the femoral condyles separated anteriorly by?
Patellar surface
An asymmetric, shallow, saddle-shaped groove
What are the femoral condyles separated by posteriorly by?
Intercondylar fossa
What are the articulating surfaces of the tibiofemoral joint?
Femoral condyles and the tibial plateaus
T/F the medial tibial plateaus is larger than that of the lateral
True
What are the medial and lateral tibial plateaus separated by?
Intercondylar tubercles
The menisci is a(n)____
The menisci is a wedged-shaped fibrocartilage disc
Coronary ligaments and the anterior transverse ligaments are attached to the
Menisci
T/F the menisci are highly vascularized
False
T/F there is no loss of knee function when the menisci are removed
True
Which of the menisci is larger and more likely to get injured?
The Medial Meniscus
Opposed to the lateral meniscus
What enhances the stability of the knee by distributing weight, deepening the articular surfaces, and reduces friction between articular surfaces?
The menisci
Describe the movement of the medial meniscus during extension and flexion
Extension: Moves posteriorly (due to tension in semimembranous muscle)
Flexion: Drawn forward (due to tension in anterior capsular fibers)
What is:
Large and Lax
Deficient on lateral condyle: For passage of the popliteal tendon
Anterior wall replaced by quadriceps tendon
Excludes cruciate ligaments
Commonly communicates with synovial bursae
Joint Capsule
Upward expansion of synovial cavity between femur and quadriceps muscles and tendon
Proximally receives insertion of articularis genus muscle
Suprapatellar Bursa
Lies between superficial surface of patella and skin
Prepatellar Bursa
Lies between patellar ligament and tibia
May become inflamed as a result of excessive kneeling
Deep Infrapatellar Bursa ***
Located between tendon popliteus muscle and later condyle of tibia
Subpopliteal Bursae
Under medial head of gastrocnemius
Gastrocnemius Bursae
What is a Bursa (Bursae)?
a fluid-filled sac or saclike cavity, especially one countering friction at a joint.
Between pes anserinus and tibial collateral ligament
Anserine Bursa
Note: Pes anserine = combined tendons of semitendinosus, gracilis, and sartorius
The medial collateral ligament is a connection between___
The medial femoral condyle and the proximal tubule
Note that it is continuous with the adductor Magnus tendon and is associated with the meniscus
What splits the tendon of biceps femoris muscle?
Hint: It also is separated from lateral meniscus by popliteal tendon
Lateral (fibular) collateral ligament
What ligament prevents backward sliding of the femur on the tibia and prevents hyperextension of the knee?
Anterior cruciate
What ligament is slack during flexion and taut during extension?
Anterior cruciate
What ligament is taut during flexion and is slack during extension?
Posterior cruciate
What ligament prevents forward siding of the fumer on the tibia and prevents hyperextension of the knee?
Posterior cruciate
During the first part, in flexing the knee, what is happening?
Posterior rolling and spinning
Rolling femur posteriorly and spinning condyle on the plateau
When does anterior sliding of the femoral condyles on tibial plateaus occur?
Flexion of the knee
During the first part, in extension the knee, what is happening?
Femoral condyles roll anteriorly and slide posteriorly
Note: This is followed by rolling and spinning of condyles
When the knee is flexed at a 90-degrees angle, how many degrees can the tibia rotate?
30 degrees of medial rotation
40 degrees of lateral rotation
T/F When the knee is flexed GREATER than 90-degrees, medial and lateral rotation’s range of motion increases
False; it decreases
Where is the patella embedded?
The joint Capsule
Between what two structures can the patella be found and attached to?
Attached to the quadriceps via the quadriceps tendon and to the tibial tuberosity via the ligamentum patellae
The central ridge of the patella slides along the central groove of the femur during
knee flexion/extension of the patellofemoral joint
The tibia moves posteriorly and the ligamentum patellae pulls the patella distally and posteriorly during
Flexion of the patellofemoral joint
Note that the ligamentum patellae pulls the patella distally and posteriorly causes the patella to remain firmly in apposition to the femur
The patella is pulled proximally to the quadriceps, the vastus lateralis tends to pull the patella laterally, and the vastus medialis oblique counteracts vastus lateralis during
extension of the patellofemoral joint
Q-angle of the patellofemoral joint
is 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
What happens to the femur during the last few degrees of extension?
Femur rotates medially on tibia
Note that the tibia would also rotate on the femur laterally
What is the locked or screw-home mechanism?
Tibial tubercles are lodged in intercondylar notch
+
Menisci are tightly interposed between tibial and femoral condyles
This happens during the final few degrees of extension (Locking at full extension)
What laterally rotates femur for unlocking at the beginning of knee flexion?
The popliteus
He especially noted this
What is a medial deviation of the tibia reuslting in a greater than 170 degree angle and results in “bow legs”
Genu varum
What is a lateral deviation of the tibia resulting in a lesser than 170 degree angle and results in “knock knees”
Gen valgum
What is the normal angle at the knee where femoral and tibial axes meet?
170-175 degrees
What is the mechanical axis of the knee?
Head of femur to head of talus
Where does the anatomic axis of the knee extend?
Extends along the femoral shaft
T/F the popliteal fossa is the anterior aspect of the knee?
False it is the posterior
What is the bony landmark of the popliteal fossa?
The popliteal surface of the femur (floor)
What are the boundaries of the popliteal fossa?
Superior: Semimembranous and semitendinosus
Inferior: Medial and lateral heads of gastrocnemius
What is contained in the popliteal fossa?
Fat Several popliteal lymph nodes Popliteal bursa Superficial to deep: Tibial Nerve, Popliteal Vein, Popliteal Artery Common Peroneal (fibular) nerve Small saphenous vein
The popliteal arty is a continuation of the
femoral artery
The lateral and medial superior geniculars, The lateral and medial inferior geniculars, and the Middle genicular are branches off of
The popliteal artery
Note: they create the genicular anastomoses
What divides into anterior and posterior tibial arteries?
Popliteal artery
What is the popliteal vein formed by?
Venae comitantes
Note: it receives from the small saphenous vein and becomes the femoral vein at the adductor hiatus
The tibial nerve is a part of the
Sciatic nerve
The common peroneal fibular nerve is part of the
Sciatic Nerve
Sural nerve arises from
the tibial nerve
What forms the genicular anastomosis
Genicular branches of the popliteal artery
Branches of anterior tibial: circumflex fibular and anterior tibial recurrent
Branches of posterior tibial: posterior tibial recurrent
Note: it is a branch from the femoral artery via the descending genicular artery
