Knee Flashcards
Rectus femoris
Origin - Anterior iliac spine and acetabulum
Insertion - Base of patella
Nerve supply - Femoral nerve
Extends the knee and flexes the hip
Main divisions of the knee joint
Posterior femoral group (3 muscles)
Anterior femoral group (4 muscles
Muscles of medial thigh (sartorius and gracillis)
Muscles of deep posterior leg (popliteus)
Vastus lateralis
Origin - upper part of intertrochanteric line and lower border of greater trochanter
Insertion - base and lateral border of patella
Nerve - Femoral Nerve
Extends the knee
Vastus medialis
Origin - Lower part intertrochanteric line and upper part medial supercondylar line
Insertion - medial border of patella
Nerve - femoral nerve
extends the knee
Vastus intermedius
Origin - Upper 2/3 of anterior and lateral surface of femur
Insertion - Base of patella with rectus femoris
Nerve - femoral nerve
extends the knee
Function of the quads
Powerful extensor
Work eccentrically to control flexion
Sartorius
Origin - ASIS
Insertion - Upper medial part shaft of tibia
Nerve - femoral nerve
Flexion, lateral rotation and Abduction of the hip
Flexes the knee
Hamstrings
Semitendinosus - half tendon
Semimembranosus - half membrane
Bicep femoris - 2 heads
All supplied by sciatic nerve
All produce flexion of knee and hip extension
Function of hamstrings
Balancing pelvis on trunk
Returning the upper body to upright from being bent forwards
Deceleration of the tibia in gait
Tensor fascia Lata
Origin - ASIS and iliac crest
Insertion - lateral tibial condyle
nerve - Superior gluteal nerve
adducts and medially rotates the hip, assists in knee flexion
Popliteus
Origin - outer surface lateral condyle of femur
Insertion - posterior surface of tibia above soleal line
Nerve - Tibial nerve
Flexes the knee and medially rotates the tibia
Unlocks the knee when the foot is fixed enabling it to flex
Popliteus is the key that unlocks the knee
Function of the knee
Mobility
Weight bearing
stability
articular surfaces
Femur:
Convex femoral condyles
Intercondylar notch continues groove of the patella surface
Tibia:
Flat and separated by intercondylar eminence
eminence lodges into intercondylar notch of femur
Concave
Patella
Oval articular surface
Divided into lateral and medial facets
Valgus and Varus
Varus - outward angle
Valgus - inward angle
(knock knees)
Joint capsule
Knee is surrounded by thick ligamentous sheath composed mainly of muscle tendons
No complete independent fibrous capsule
Synovial membrane
Lines the joint capsule
Tibia: towards cruciate ligaments so they are intracapsular but extrasynovial
Patella: membrane extends as the suprapatella bursa which prevents friction between quads and femur
Functions of Menisci
Improve Congruence
Weight bearing
Shock absorb
Aid lubrication
Participate in locking mechanism
Menisci
in cross section between femoral and tibial condyles
Mede of fibrocartilage and crescent shaped
Medial menisci - broader posteriorly than anteriorly
Lateral - uniform width
In flexion menisci move posteriorly on the tibial condyles so posterior parst project beyond tibial condyles
In extension menisci move anteriorly with anterior parts projecting beyond the anterior tibial condyles
Transverse ligament connects 2 menisci anteriorly
Knee extension
As its convex on concave it glides posteriorly and rolls anteriorly
Posterior cruciate ligament prevents it from sliding off backwards (dislocating)
As tibia is fixed the femur medially rotates at the end of extension
This rotation at the end of extension is the locking of the knee
Ligamentum patellae
Very strong ligament
Connects apex of patella to the tibial tuberosity
Semitendinosus
Origin - lower medial facet on ischial tuberosity
Insertion - Medial surface upper part of tibia
Nerve - sciatic nerve
Semimembranosus
Origin - Upper Lateral facet on ischial tuberosity
Insertion - Posteromedial surface of medial tibial condyle
Nerve - Sciatic
Bicep Femoris
Origin - lower medial facet on ischial tuberosity
Insertion - Head of fibula
Nerve - Sciatic nerve
