knee joint Flashcards
what kind of joint is the knee joint
modified synovial hinge joint
what articulations make up the knee joint
3 separate articulations
- 1 femoropatellar
2x femorotibial
describe the articular surfaces of the inferior surface of the femur
patellar surface anteriorly (the lateral side of which extends more anteriorly to resist lateral dislocation of patella)
medial and lateral condyles posteriorly
intercondylar fossa
is the medial or lateral condyle of the femur larger
medial
what shape is the patellar surface of the femur
concave
what separates the medial and lateral condyles on the femur
intercondylar fossa
describe the superior surface of the tibia
medial and lateral condyles separated by a non-articular ridge called the intercondylar eminence
describe the articular (posterior) surface of the patella
apex pointing inferiorly
2 facets - larger lateral facet and smaller medial facet
- the lateral border of the femur extends more anteriorly to match larger lateral facet of patella
capsular attachments on the femur largely follow what except where
margin of articular surface except posteriorly where intercondylar fossa is enclosed in the capsule
anteriorly the capsule of the knee joint fuses with what
quadriceps tendon, patella and ligamentum patellae
where does ligamentum patellae attach
tibial tuberosity
describe the capsular attachments on the tibia
around the margins of the tibial plateau except posteriorly where there is a deficit behind lateral condyle to allow passage of popliteus
describe the synovial membrane attachment on the patella and femur
attaches around the margins of the articular surfaces
describe the synovial membrane attachment on the tibia
mostly follows the margins of the articular surfaces; forms an infrapatellar fold which excludes the intercondylar eminence from the synovial cavity and anteriorly there are alar folds covering fat pads on either side of patellar ligament
what does the infrapatellar synovial connect
connects the intercondylar fossa on femur and intercondylar eminence on tibia - separates joint cavity into two separate spaces
what bursae around the knee are in communication with the synovial cavity of the knee
suprapatellar
gastrocnemius
semimembranosus
popliteus
what bursae around the knee are not in communication with the synovial cavity of the knee
- subcutaneous prepatellar
- subcutaneous infrapatellar
- deep infrapatellar
- anserine
the anserine bursae is related to what tendons
gracilis, sartorius and semitendinosus
the suprapatellar bursae extends superiorly on anterior aspect of knee and is held in place by deep fibres of what
vastus intermedius
what are the extracapsular ligaments of the knee
oblique popliteal
arcuate popliteal
medial and lateral collateral
what are the intracapsular ligaments of the knee
anterior and posterior cruciate
the oblique popliteal is an expansion of what
semimembranosus
what is the function of the oblique popliteal ligament
reinforces posterior capsule
what is the arcuate ligament
thickening of capsule over popliteus
what is the function of the arcuate ligament
strengthens posterolateral joint capsule
describe the gross appearance of the medial (tibial) collateral ligament
strong, flat thickening of capsule that blends with capsule
what are the attachments of the medial collateral ligament
medial epicondyle of the femur to the medial condyle and superior medial surface of tibia
- also deep fibres attach to medial meniscus
what do the collateral ligaments prevent
side to side movement within the joint - abduction and adduction
which meniscus is more firmly attached to the tibial condyle
medial
describe the gross appearance of the lateral (fibular) collateral ligament
strong and cord like and doesnt blend with capsule
the lateral collateral ligament passes superficial to what tendon
popliteus
the lateral collateral ligament causes what tendon to split
biceps femoris
what are the attachments of the lateral collateral ligament
lateral epicondyle of femur to lateral head of fibula
what is the function of the cruciate ligaments
maintain contact between femoral and tibial articular surfaces, particularly when knee is flexed
how is medial rotation of the tibia limited to 10 degrees
PCL and ACL wind round eachother during this movement
the PCL prevents the femur from sliding…
anteriorly on the tibia, particularly when the knee is flexed
the ACL prevents the femur from sliding…
posteriorly on the tibia - preventing hyperextension of the knee
the ACL also prevents … rotation of the femur when the foot is planetd
medial rotation
are the cruciate ligaments intracapsular
yes - intracapsular but extrasynovial
the cruciate ligaments are named based on what
attachment on intercondylar eminence i.e. ACL is more anterior on tibia and more posteriorly on femur
why is there a greater degree of lateral rotation at the knee than medial rotation
during medial rotation the cruciates wind round eachother
what are the attachments of the ACL
anterior intercondylar eminence to the medial side of the lateral condyle of the femur (goes posterolaterally)
what are the 2 bands of the ACL
anteromedial and posterolateral
the anteromedial band of the ACL limits
flexion
the posterolateral band of the ACL limits
extension
the ACL spirals through ___ degrees between tibia and femur
110
what is the advantage of having 2 bands in the cruciate ligaments
ligament is in part taut in all positions
what are the attachments of the PCL
posterior intercondylar eminence to the lateral side of the medial condyle of femur
(goes anteromedially)
what are the two bands of the PCL
anterolateral and posteromedial
the anterolateral band of the PCL limits
flexion
the posteromedial band of the PCL limits
extension
the PCL is closely aligned to what
centre of rotation of knee
what does the alignment of the PCL with the centre of rotation of the knee mean for this ligament
it is the ligament that supports the weight of the body when knee is flexed
what are the menisci made of
fibrocartilage
what is the function of the menisci
deepen articular surface to maximise contact surface and shock absorption
what shape is the medial meniscus
C shape
what shape is the lateral meniscus
circular
the medial meniscus is broad where
posteriorly
the medial meniscus is firmly attached to what
medial collateral ligament
is the lateral meniscus fixed
no, freely moveable
the lateral meniscus provides attachment for what
popliteus
what is the function of the MCL
prevent abduction
when is the MCL most likely to be injured
lateral force injury
if the foot is planted in a lateral force injury tearing the MCL what else will be damaged and what is this called
unhappy triad - MCL attached to medial meniscus so this tears and if it is a rotational force, the ACL will tear
- unhappy triad
what are the proximal attachments of popliteus
starts within the joint capsule attached to lateral epicondyle of the femur and some fibres on lateral meniscus
what does popliteus do during flexion
pulls lateral meniscus into a better position to accomodate the lateral femoral condyle
what is the anastomosis around the knee called
periarticular genicular anastomosis
what vessels contribute to the periarticular genicular anastomosis
- 4 x genicular branches from popliteal artery
- descending genicular artery from femoral artery
- descending branch from lateral circumflex femoral artery
- branches from the anterior tibial recurrent artery
- can also have branch from posterior tibial recurrent
what are the 5 genicular branches of the popliteal artery
- middle which pierces joint capsule
- superior and inferior medial
- superior and inferior lateral
where does the femoral artery run between
inguinal ligament to adductor hiatus
what does the femoral artery become at the adductor hiatus
popliteal artery
what does the popliteal artery terminate as
anterior and posterior tibial arteries
