Knee popliteal fossa Lecture 11

Question 1

What are the articulating surfaces of the knee?

Answer 1

Femoral condyles that are convex and asymmetric with the tibial plateaus which are concave and asymmetric.

Question 2

Classification of knee joint?

Answer 2

Modified hinge joint

Question 3

Describe menisci with regard to functions movements and attachmetns.

Answer 3

They are made of fibrocartilage,Ends of the menisci are attached to tibial intercondylar tubercles and the coronary ligaments attach the menisici to rims of plateaus.
Function is to enhance the stability of the knee, distribute weight and reduce friction btw articular surfaces.
Move during movement

Question 4

What separates tibial plateaus?

Answer 4

intercondylar tubercles

Question 5

What surface of the tibial plateaus is larger?

Answer 5

Articular surface of medial plateau is 50% larger than lateral

Question 6

Characteristics of joint capsule?

Answer 6

Large and lax, deficient on lateral condyle to allow popliteal tendon to pass, lacking anteriorly it is replaced by quadriceps tendon. Joint capsule excludes cruciate ligaments, they are outside capsule. Communicates with synovial bursae

Question 7

Major bursae associated with knee complex?

Answer 7

Suprapatellar: upward expansion of synovial cavity btw femur and quads mm.
Prepatellar: btw superficial surface of patella and skin
Deep Infrapatellar: lies btw patellar ligament and tibia
Subpopliteal: btw tenson of popliteus mm and lateral condyle of tibia
Gastrocnemius: under medial head of gastrocnemius
Anserine: between pes anseinus and tibial collateral lig

Question 8

Where are cruciate ligaments found?

Answer 8

anterior and posterior intercondylar areas

Question 9

What attaches the menisci together and allows them to move together?

Answer 9

Anterior transverse ligament

Question 10

Characteristics of menisci in general?

Answer 10

Fibrocartilage discs that do not heal well due to poor vascularization. No loss of function if removed

Question 11

Characteristics of medial meniscus?

Answer 11

Medial is larger of the two it is more securely attached and attached to MCL and semimembranosus muscle so more often injured.

Question 12

Characteristics of lateral meniscus?

Answer 12

Attached to posterior cruciate ligament through the meniscofemoral ligament attaches to popliteus muscle.

Question 13

How does the medial meniscus move during flexion?

Answer 13

Moves posteriorly during flexion due to tension in the semimembranous muscle

Question 14

How does the medial meniscus move during extension?

Answer 14

Moves forward due to tension in anterior capsular fibers

Question 15

How does the lateral meniscus move during flexion?

Answer 15

Posteriorly due to tension in popliteal expansion and it distorts more than medial meniscus

Question 16

What bursae may become inflamed from excessive kneeling?

Answer 16

Deep infrapatellar

Question 17

Describe and compare characteristics of lateral and medial collateral ligaments.

Answer 17

Medial is also called tibial, it attaches on medial femoral ocndyle, proximal tibia, and partly continuous with adductor magnus tendon.

Lateral aka Fibular, splits tendon of biceps femoris, separated from lateral meniscus by popliteal tendon

Question 18

Describe and compare cruciate ligaments.

Answer 18

Anterior is weakest of cruciate, slack during flexion taut during extension, prevents backward sliding of femur on tibia and hyperextension.

Posterior is taut during flexion and slack during extension. Prevent forward sliding of femur on tibia, prevents hyperflexion of knee

Question 19

List stages of knee action in flexion and degree of movement?

Answer 19

0-25 degrees posterior rolling and spinning of femur on tibia, anterior sliding of femoral condyles on tibial plateaus

Question 20

List stages of knee action in extension and degree movement?

Answer 20

Femoral condyles roll anteriorly and slide posteriorly followed by rolling and spinning of condyles.

Question 21

List stages of knee action in medial and lateral roatation, and degree of movement?

Answer 21

At 90 degrees flexion up to 40 degrees lateral rotation and 30 degrees of medial rotation.

Greater than 90 degrees of flexion medial and lateral roatation of ROM decreases

Question 22

What is the pes anserinus?

Answer 22

Combined tendons of semitendinosus gracilis and sartorius

Question 23

What is involved in locking of knee at full extension?

Answer 23

Full extension is when this occurs, the femur rotates medially on tibia and tibia rotates laterally on femur. This brings knee to close-packed position in which tibial tubercles are lodged into intercondylar notch and menisci are tight in between tibial and femoral condyles.

Question 24

Name the muscle involved in unlocking knee from full extension.

Answer 24

Popliteus, it rotates femur on tibia laterally to begin flexion.
TEST

Question 25

Describe mechanical and anatomical axes?

Answer 25

Mechanical is head of femur to head of talus almost equivalent to anatomic axis of tibia. Anatomic axis extends along femoral shaft

Question 26

Patellofemoral Joint?

Answer 26

Patella embedded in joint capsule and attaches to quadriceps through the quad tenon and to tibial tuberosity via ligamentum patellae.

Question 27

Patellofemoral joint during flexion/extension?

Answer 27

During flexion tibia moves posteriorly and ligamentum patellae pulls patella distally and posteriorly, patella remains firmly in apposition to femur During extension patella is proximally pulled by quadriceps, vastus lateralis pulls patella laterally, vastus medialis counteracts vastus lateralis

Question 28

What is the Q angle and axes that determine it?

Answer 28

Q angle is formed by vectors of quadriceps muscles from ASIS to middle of patella. Also from vector of pull of ligamentum patellase from tibial tubercle to middle of patella. Its 15 degrees

Question 29

Physiologic valgus?

Answer 29

Normal angle at knee where femoral and tibial axes meet around 170-175 degrees

Question 30

Genu Valgum?

Answer 30

Lateral deviation of tibia, less than 170 degrees results in knock knees

Question 31

Genu Varum?

Answer 31

Medial deviation of tbia, greater than 170 degrees, results in bow legs

Question 32

Boundaries of popliteal fossa?

Answer 32

Floor: popliteal surface of femu Superior: semimembranosus and semitendinosus Inferior: medial and lateral heads of gastrocnemius

Question 33

List contents of popliteal fossa.

Answer 33

Fat, several popliteal LN, popliteal bursa, | Tibial nerve, popliteal vein, popliteal artery (superficial-deep), common fibular nerve, small saphenous veins

Question 34

Describe origin of sural nerve.

Answer 34

Arises from communicating branch of tibial nerve, communicating branch from common peroneal nerve

Question 35

Politeal artery is a continuation of what?

Answer 35

Femoral artery, it begins at adductor biatus and ends at lower border of popliteus muscle

Question 36

Branches off of popliteal artery?

Answer 36

Lateral and medial superior genicular Lateral and medial inferior genicular Middle genicular

Question 37

Popliteal vein formed from, receives blood from?

Answer 37

Formed from vena comitantes of anterior and posterior tibial arteries. Receives lesser saphenous vein and becomes femoral vein at adductor hiatus

Question 38

Structure and components of genicular anastamosis?

Answer 38

Descending genicular from femoral Descending branch of lateral femoral circumflex Genicular branches from popliteal artery Branches off of anterior tibial (circumflex fibular and anterior tibial recurrent) Branches off of posterior tibial (posterior tibial recurrent)