Download THE KNEE JOINT

THE KNEE JOINT
Muscles That Act On The Knee
Muscles of the Knee Joint

Hamstrings


Quadriceps


All - flexion
All - extension
Unclassified




Sartorius - flexion and internal rotation
Gracilis - flexion and internal rotation
Popliteus - flexion (unlocking) and internal rotation
Gastrocnemius - flexion
Anterior Muscles

Quadriceps

knee extension
Quadriceps Muscles
Rectus femoris




Two joint muscle; most
superficial
Origin: anterior-inferior iliac
spine of the ilium
Insertion: top of the patella and
patellar ligament to the tibial
tuberosity
Actions:

Extension of the knee
Vastus lateralis



Origin: Lateral lip of linea
aspera.
Insertion: Outer half of the
upper border of the patella
and the patellar ligament
and the anterior tuberoscity
of the tibia
Action:

Extension of the knee
Vastus
intermedius
Origin: Upper 2/3 of the
anterior surface of the
femur
 Insertion: Upper border
of the patella and the
patellar ligament
 Action:


Extension of the knee
Vastus medialis



Origin: Medial lip of the linea
aspera and the internal
condyloid ridge
Insertion: Inner half of the
upper border of the patella nd
patellar ligament
Action:

Extension of the knee
VL
RF
VM
VL RF VM
Quadriceps
•Vastus Lateralis
•Vastus Intermedius
•Rectus Femoris
•Vastus Medialis
1
2
3
Hamstrings
QUADRICEPS MUSCLES
Vertical jumping
 Decelerating or eccentric contraction
during landing or changing directions
 As a group, they are typically 25-30%
stronger than the hamstrings

Posterior Knee
Muscles
Hamstrings

knee flexion
Biceps femoris


Lateral side
Origin:




1.) Long head - ischial tuberosity;
2.) Short head - lower half of the linea aspera
Insertion: Head of the fibula
Action:

Flexion of knee
Semitendinosus




Medial side; superficial
Origin: Ischial tuberosity
Insertion: Anterior medial
surface of the tibia
Action:

Flexion of the knee
Semimembranosus




Medial side, deeper than
semitendonosus
Origin: Ischial tuberosity
Insertion: Anterior medial surface
of the tibia
Action:

Flexion of the knee
HAMSTRING MUSCLES
More “knee flexors” than “hip extenders”
 Acceleration muscles during running
 Tight hamstring muscles can contribute to
lower back, hip and knee problems

Gracilis
O: Pubis crest
 I: Anterior medial
surface of the tibia
 Actions:


flexion at the knee
Sartorius




Posterior at the knee joint
Origin: Anterior-superior spine
of the ilium
Insertion: Anterior medial
surface of the tibia
Action:


Flexion at the knee
From Late Latin sartor, tailor (from
its producing the cross-legged
position of a tailor at work)
Popliteus
Origin: Lateral condyle of the
femur
 Insertion: Proximal third of
posterior aspect of the tibia
 Action:




Flexion of the knee
It "unlocks" the knee.
Only true knee flexor
Gastrocnemius
Origin: posterior
surface of the medial
and lateral femoral
condyles
 Insertion: the calcaneus
through the Achilles
tendon
 Actions:


Flexion of the knee
Posterior
Review

Superficial Leg Muscles
Name the muscle and its action(s)
Sartorius
Action: Flexion at the knee
Terms
1.
2.
3.
Q Angle
Valgus
Varus
1.
2.
3.
The deviation between
the line of pull of the
rectus femoris and the
patellar ligament.
Stress to lateral side of
the knee
Stress to the medial side
of the knee
Name the muscle and its action(s)
Semimembranosus

Action:

Flexion of the knee
1.
2.
3.
4.
5.
6.
Anterior cruciate
ligament
Lateral collateral
ligament
Lateral meniscus
Posterior cruciate
ligament
Medial collateral
ligament
Medial meniscus
1.
4.
2.
5.
3.
6.
Name the muscle and its action(s)
Semitendinosus

Action:

Flexion of the knee
1 = PCL
2 = Lateral meniscus
3 = ACL
4 = Medial meniscus
1.
4.
2.
3
Name the colored muscles
2 = Vastus lateralis
1 = Rectus femoris
4 = Vastus medialis
Femur
?=
?=
?=
Lateral condyle
Medial condyle
Intercondylar fossa
Name the muscle and its action(s)
Gracilis
Action - flexion at the knee
? = Medial condyle
? = Lateral condyle
? = Medial Malleolus
Tibia
2.
1.
3.
1.
= Vastus lateralis
2.
= Rectus femoris
3.
= Vastus medialis
VL
RF
VM
VL RF VM
Name the muscle and its action(s)
Rectus femoris

Actions:

Extension of the knee
1.
2.
3.
3.
4.
1. = Anterior cruciate ligament
2. = Lateral collateral
3. = Lateral meniscus
3. = Medial collateral
4. = Medial mieniscus
Name the muscles.
1 = Vastus lateralis
2 = Vastus intermedius
1.
2.
3 = Vastus medialis
3.
? = Head
? = Lateral malleolus
Fibula
Name the muscles
1.
2.
3.
4.
Biceps femoris
Biceps femoris
Semitendonosis
Semimembranosis
Name the muscle and its action(s)
Biceps femoris

Action:

Flexion of knee
Tibia
? = Medial condyle
? = Lateral condyle
? = Medial Malleolus
Name the muscle and its action(s)
Popliteus

Action:

Flexion of the knee
Femur
6=?
7=?
8=?
Lateral condyle
Intercondylar fossa
Medial condyle
Name the muscle and its action(s)
Sartorius
Action: Flexion at the knee
3.
4.
1.
2.
1 = Medial meniscus
2 = PCL
3 = ACL
4 = Lateral meniscus