Knee Flashcards
Knee joint
Links 2 largest bones in the body
largest and one of most complex joints
joint
femur
patella (kneecap)
tibia
fibula
functions
support body weight
transmit forces between femur and tibia
provide movement for movement and activity
stability
has to absorb the body weight and take impacts
mobility
allows freely moving actions flexion and extension
tibiofemoral joint
synovial joint
between femoral condyles and tibial articular surfaces
femoral concyles
at the distal end of femur
tibia condyles
at proximal end of tibia
medial articular surface
larger and more oval
lateral articular surface
smaller and circular
function of menisci located at joints
increase congruence between articular surfaces
assist weight bearing across joint
shock absorbers
facilitate accessory movements
4 major ligaments of the knee
medial collateral ligament
lateral collateral ligament
anterior cruciate ligament
posterior cruciate ligament
Medial collateral ligament (MCL)
broad flat band, 10cm long
extra-capsular
prevent valgus displacement- prevent adduction of a joint
lateral collateral ligament (LCL)
extra-capsular
a strong cord
prevents varus displacement- prevent abduction of a joint
anterior cruciate ligament (ACL)
intra-capsular
from anterior intercondylar area of tibia to lateral femoral condyle
prevents anterior tibial displacement- knee moving forwards away from joint
Posterior Cruciate ligament (PCL)
intra-capsular
posterior intercondyar area of tibia to medial femoral condyle
prevents posterior tibial displacement- knee moving backwards from joint
patellofemoral joint
synovial saddle joint
between
articular surface of patella
and
patellar surface of femur
patella
largest sesamoid bone in body
embedded in tendon of quadriceps
patella function
an anatomic pulley
reduces friction between quadriceps tendon and femoral condyles
patella (articular surface)
oval shaped, cartilage covered
vertical ridge separates medial and lateral areas
lateral area larger
medial area samller
femoral condyles- patellar surface of femur
cartilage-covered surface which articulates with patella
PFJ (inferior view)
patella ridge articulates with groove of patellar surface
patella movements
moves distally in flexion
moves proximally in extension
shared features between the joints
joint capsule
reinforced by ligaments and tendons when complete
bursae
fluid- filled sacs
reduce friction
13-15 in knee area
a bi-axial joint
tibiofemoral joint is bi-axial
movements occur in 2 planes/ around 2 axis
movements
- flexion and extension around horizontal axis in sagittal plane
- medial and lateral rotation around vertical axis in transverse plane
flexion and extension ROM
140 degrees flexion
0 degrees extension
medial and lateral tibial rotation
at 90 degrees flexion
25 degrees medial rotation
40 degrees lateral rotation
close packed position- knee locking mechanism
close-packed position of knee is full extension
no rotation possible in this position
knee locking mechanism
There is the observable rotation of a knee during flexion as well as extension.
The rotation is important for the healthy motion of a knee.
During the last 30 degrees of the knee extension, a tibia (open chain) or even femur (closed chain) must externally or internally rotate, respectively, about 10 degrees.
This slight rotation is owing to the inequality of an articular surface of the femur condyles.
Rotation must happen to achieve full extension & then flexion from full extension.
knee flexors
Biceps femoris,
semimembanosus,
semitendinosus,
sartorius,
gracilis
bicep femoris (flexor)
Origin: Ischial tuberosity, linea aspera, and lateral supracondylar line.
Insertion: Head of fibula.
Action: Flexes and laterally rotates leg at knee joint; extends thigh at hip joint.
Innervation: Tibial (L5-S2) and common fibular (L5-S2) divisions of sciatic nerve.
semimembranosus (flexors)
Origin: Ischial tuberosity.
Insertion: Medial condyle of tibia.
Action: Flexes and medially rotates leg at knee joint; extends thigh at hip joint.
Innervation: Tibial division of sciatic nerve
semitendinosus
Origin: Ischial tuberosity.
Insertion: Medial aspect of proximal part of tibia.
Action: Flexes and medially rotates leg at knee joint; extends thigh at hip joint.
Innervation: Tibial division of sciatic nerve
sartorius
Origin: Anterior superior iliac spine.
Insertion: Medial aspect of proximal part of tibia.
Action: Flexes and medially rotates leg at knee joint; assists in flexion, abduction and lateral rotation of thigh at hip joint.
Innervation: Femoral nerve
gracilis
Origin: Body of pubis and inferior pubic ramus.
Insertion: Medial aspect of proximal part of tibia.
Action: Flexes and medially rotates leg at knee joint; assists in adduction of thigh at hip joint.
Innervation: Obturator nerve
knee extensors
Rectus femoris,
vastus lateralis,
vastus medialis,
vastus intermedius,
tensor fascia latae
Rectus femoris
Origin: Anterior inferior iliac spine and supraacetabular groove of ilium.
Insertion: Tibial tuberosity, via tendon of quadriceps femoris muscle and patellar ligament.
Action: Extends leg at knee joint; flexes thigh at hip joint.
Innervation: Femoral nerve
vastus lateralis
Origin: Intertrochanteric line, greater trochanter, gluteal tuberosity, and lateral lip of linea aspera of femur.
Insertion: Tibial tuberosity, via tendon of quadriceps femoris muscle and patellar ligament; lateral border of patella.
Action: Extends leg at knee joint.
Innervation: Femoral nerve
vastus medialis
Origin: Medial part of the intertrochanteric line and medial to the spiral line and linea aspera of the femur, extending inferiorly to the medial supracondylar line.
Insertion: Tibial tuberosity, via tendon of quadriceps femoris muscle and patellar ligament, and medial border of patella.
Action: Extends leg at knee joint.
Innervation: Femoral nerve
vastus intermedius
Origin: Anterior and lateral surfaces of body of femur.
Insertion: Tibial tuberosity, via tendon of quadriceps femoris muscle and patellar ligament.
Action: Extends leg at knee joint.
Innervation: Femoral nerve
tensor fascia latae
Origin: Anterior superior iliac spine and anterior one third of outer lip of iliac crest.
Insertion: Tubercle of iliotibial tract on the tibia, via iliotibial tract.
Action: Assists in medial rotation, abduction, and flexion of thigh at hip joint.
Innervation: Superior gluteal nerve
Popliteus- rotates the femur on a fixed tibia unlocking the knee in extention
Popliteus-
Origin: Groove for popliteus muscle.
Insertion: Posterior surface of tibia, superior to soleal line.
Action: Medially rotates leg at knee joint; “unlocks” knee joint at beginning of knee flexion.
Innervation: Tibial nerve
medial rotators
Semimembranosus,
semitendinosus,
sartorius,
gracilis
Semimembranosus
Origin: Ischial tuberosity.
Insertion: Medial condyle of tibia.
Action: Flexes and medially rotates leg at knee joint; extends thigh at hip joint.
Innervation: Tibial division of sciatic nerve
semitendinosus
Origin: Ischial tuberosity.
Insertion: Medial aspect of proximal part of tibia.
Action: Flexes and medially rotates leg at knee joint; extends thigh at hip joint.
Innervation: Tibial division of sciatic nerve
sartorius
Origin: Anterior superior iliac spine.
Insertion: Medial aspect of proximal part of tibia.
Action: Flexes and medially rotates leg at knee joint; assists in flexion, abduction and lateral rotation of thigh at hip joint.
Innervation: Femoral nerve
Gracilis
Origin: Body of pubis and inferior pubic ramus.
Insertion: Medial aspect of proximal part of tibia.
Action: Flexes and medially rotates leg at knee joint; assists in adduction of thigh at hip joint.
Innervation: Obturator nerve
lateral rotators
bicep femoris-
When the knee is semiflexed, the biceps femoris acts to produce external rotation of the leg at the knee12. The long head of the biceps femoris is a weaker knee flexor when the hip is extended and a weaker hip extender when the knee is flexed2. In consequence of its oblique direction, the biceps femoris rotates the leg slightly outward when the knee is semi-flexed
bicep femoris
Origin: Ischial tuberosity, linea aspera, and lateral supracondylar line.
Insertion: Head of fibula.
Action: Flexes and laterally rotates leg at knee joint; extends thigh at hip joint.
Innervation: Tibial (L5-S2) and common fibular (L5-S2) divisions of sciatic nerve.
