Flashcards in MSK Session 9 Deck (83):
Why can the knee be locked in extension?
To reduce energy needed to remain upright
How is the knee locked and unlocked in extension?
Femur rotates internally over tibia to lock
Popliteus helps rotate femur externally to unlock
Which muscles are used for movement at the knee joint?
Medial rotation: semitendinous
Lateral rotation: biceps femoris
When can rotation of the knee joint occur?
Why must the knee joint be deepened?
To stabilise the mismatch b/w shapes on the tibial plateau
How is the knee joint deepened?
Deepening the articular surface of the tibial element w/the menisci
What shape do the medial and lateral menisci have?
Thicker at edges than in middle
What shape are the medial menisci?
Which menisci are more circular and more mobile?
What ensures synovial fluid is distributed evenly in the knee?
What do the menisci attach to?
Joint capsule via coronary ligaments
Each other by transverse ligament of the knee
What supplies blood to the knee joint?
10 vessels of peri-articular be ocular anastomoses around knee
What especially stabilises the knee joint?
Inferior fibres of vastus medialis and vastus lateralis
What supports the knee laterally?
Which blood vessels are involved in supplying the knee?
Femoral, popliteal, anterior and posterior recurrent branches of the anterior tibial recurrent and circumflex fibular arteries
How are the medial and lateral tibial condyles distinguished?
Medial - slightly concave
Lateral - slightly convex
Where is the adductor tubercle on the femur?
On the medial epicondyle
Why is the medial epicondyle of the femur larger than the lateral?
Bears more weight
What are the intracapsular ligaments which cross over and are named by their attachment to tibia?
What is the path of the posterior cruciate ligament?
Passes anterior and inserts medially
What is the lathe of the anterior cruciate ligament?
Passes posterior and inserts laterally
What is the function of the posterior cruciate ligament?
Prevents tibia moving posteriorly in relation to femur
What is the function of the anterior cruciate ligament?
Prevents tibia moving anteriorly in relation to femur
Which is the stronger cruciate ligament?
Which is the main stabiliser cruciate ligament in weight bearing flexed knee?
What does the posterior cruciate ligament limit?
What does the anterior cruciate ligament limit?
What is the blood supply to the anterior cruciate ligament like?
What supports the knee anteriorly?
What is the oblique popliteal ligament an extension of?
Tendon of semitendinous
What supports the knee posteriorly by strengthening the capsule?
Oblique and arcuate popliteal ligaments
Which ligaments are the extra-capsular ligaments of the knee?
Where do the collateral ligaments of the knee extend from?
Where does the medial collateral ligament extend to?
Medial condyle of tibia at midpoint of medial meniscus
Why does injury of the medial collateral ligament typically cause injury of the medial meniscus?
Due to attachment
Why is the medial collateral ligament injured more than the lateral collateral ligament?
It is part of the fibrous capsule
What does the lateral collateral ligament extend to?
Lateral surface of fibula head
What reinforces the lateral collateral attachment to the lateral surface of the fibula head?
What is the unhappy triad?
Blow to side of knee --> lateral twisting of flexed knee --> medial meniscus torn, medial collateral torn, ACL torn
What is damaged in hyperextension?
Anterior cruciate ligament
What do you use to test damage to the anterior cruciate ligament?
Anterior draw sign
What is damaged by falling onto tibial tuberosity with flexed knee?
Posterior cruciate ligament
What is used to assess posterior cruciate ligament damage?
Posterior draw sign
May be visible looking side on
Is injury to the ACL or PCL more common?
Why is the lateral meniscus saved form injury and able to heal relatively well?
What are the three bursae of the knee?
What is Housemaid's knee?
Inflammation of the pre patellar bursa typically from kneeling
What is Clergyman's knee?
Inflammation of the infra-patellar bursa typically from kneeling
Why is osteoarthritis common in the knee?
When is rheumatoid arthritis seen in the knee?
In severe progression
What are Bakers cysts?
Abnormal fluid filled sacs of synovium in popliteal fossa due to chronic knee effusion
What can popliteal cysts connect to?
Synovium of knee joint
How quickly can popliteal cysts arise?
Which muscles are in the posterior thigh?
What is the main action of the semitendinous?
Medially rotate leg when flexed
Can extend trunk when thigh and leg flexed
What is the main action of semimembranous?
Rotate leg medially when flexed
Can extend trunk when thigh and leg flexed
What innervates the posterior thigh muscles?
What is the main action of biceps femoris?
Laterally rotates leg when knee is flexed
Which muscle is used to accelerate mass during first step of gait?
What is the popliteal fossa?
Diamond shaped area on posterior leg through which most structures pass from the thigh to the leg
What forms the superiomedial border of the popliteal fossa?
What forms the superiolateral border of the popliteal fossa?
What forms the inferio lateral border of the popliteal fossa?
Lateral head of gastrocnemius and plantaris
What forms the inferio medial border of the popliteal fossa?
Medial head of gastrocnemius
What forms the floor of the popliteal fossa?
Posterior surface of knee joint capsule
Posterior surface of femur
What forms the roof of the popliteal fossa?
Popliteal fascia and skin
What is the popliteal fascia continuous with?
Fascia lata of leg
What is the contents of the popliteal fossa from medial to lateral?
Common fibular nerve
What is the most superficial in the popliteal fossa?
What are the tibial and common fibular nerve branches of?
What is the deepest structure in the popliteal fossa?
What is the popliteal artery?
Continuation of the femoral artery which supplies the leg w/blood
What pierces the popliteal fascia to empty into the popliteal vein?
Small saphenous vein
What lies at the termination of the small saphenous vein?
Small lymph node
Describe the location of deep lymph nodes in the popliteal fossa.
Surround vessels and follow femoral vessels to deep inguinal lymph nodes
What does Baker's cyst aUsually arise in conjunction with?
Osteo or rheumatoid arthritis
What does rupture of a popliteal cyst cause?
Does a Baker's cyst usually self resolve?
Why does popliteal aneurysm cause compression of popliteal fossa contents?
Popliteal fascia layer is inextensible
What is particularly susceptible to compression in popliteal aneurysm?
What does tibial nerve compression in popliteal aneurysm cause?
Leg anaesthesia or loss of motor function
How can a popliteal aneurysm be detected clinically?
Obvious palpable pulsation w/abnormal arterial sounds