knee region muscle and movement Flashcards
what movement is your leg in if it is locked
in standard knee extension- the knee joint is locked in closed pack position, joint surfaces more congruent, femoral medial rotation or tibial lateral rotation anf extension tightens ligaments
where is the centre of gravity when the knee is locked
COG anterior to knee joint maintaining extension
how does the popliteus initiate unlocking mechanisms
by laterally rotating femur on fixed tibia
what position are ligamnets and posterior capsule in when the knee is locked
ligaments and posterior capsule are at their most taught- so you can rest in a very energy efficient form with the knee in closed pack position
knee locking mechanisms- closed kinetic chain- from sitting to standing
femoral condyles roll anteriorly over tibial condyles, femoral condyles glide posteriorly over tibial condyles (stops femoral condyles rolling off tibial condyles), shorter lateral femoral condyle movements stop first- shorter, femur medially rotates (spins) around fixed lateral condyle to complete the movement
knee (un) locking mechanisms
unlocking knee joint into open packed position (flexion)
knee (un) locking mechanisms closed pack mechanisms- closed kinetic chain
femur rotates (spins) laterally on the tibia, femoral condyles roll posteriorly on the tibial condyles (relatively fixed), femoral condyles glide anteriorly on the tibial condyles (this stops femoral condyles from rolling off the tibial condyles)
Knee extensors rectus femoris- origins and insertions
origins- 2 heads (bipennate)- straight head- AIIS, reflected head- rough area of ilium superior to acetabulum
insertions- 2 heads join quadriceps femoris tendon which inserts into the base of the patella
Knee extensors rectus femoris- action and nerve
action 2 joint muscle- extends knee and flexes hip, nerve supply- femoral nerve L2,3,4
Knee extensors vastus intermedius- origin and insertions
origin- femur- upper 2/3rds anterior and lateral surfaces, insertions- quadriceps tendon (deep part) and lateral border of patella
Knee extensors vastus medialis- origin and insertion
origin- femur-medial part of the intertrochanteric line, pectineal line, medial lip of linea aspera, medial supracondylar line
insertions- quadriceps tendon and medial border of patella- wrap around
vastus medialis controversy- historically
VM historically thought to be the only muscle to produce the final 15 degrees of knee extension- therefore patients were given specific exercises to train VM muscle in that range
VM controversy- modern evidence
evidence now suggests that VM is not specifically response for the final 15° of knee extension, VM acts throughout the range of knee extension with or without external resistance, VM medalists the patella
Knee extensors vastus lateralis- origin and insertion
origin- lateral part of the intertrochanteric line, lateral margin of greater trochanter, lateral margin gluteal tuberosity, lateral lip linea aspera
Vastus muscles- action and nerve supply
action- extends the knee, nerve supply- L2,3,4
Knee flexion bicep femoris- origin and insertion
origin- 2 heads long head- inferomedial part of upper area ischial tuberosity, short head- lateral lip of linea aspera (lateral supracondylar ridge)
insertion- head of fibula
Knee flexion bicep femoris- action and nerve
flexion and ER (lateral), nerve supply- sciatic nerve L5,S2
Knee flexion semitendinosus- origin and insertion
origin- inferomedial part of the upper ischial tuberosity
insertion- medial surface proximal tibia
Knee flexion semitendinosus- action and nerve
flexion and MR, nerve supply- sciatic nerve L5-S2
Knee flexion semimembranosus- origin and insertion
origin- superolateral impression ischial tuberosity
insertion- groove and adjacent bone medial and posterior surface medial tibial condyle