Motion, Flexion, & Extension of the Knee

Muscles that move, flex and extend the knee.

How many Axes of Motion does the Knee have?

1 axis, 2 motions

Hamstrings _{^{(bi-articular muscle; posterior compartment of the thigh)}}

• Crosses both posterior hip and posterior knee.

• Action: Extend the Hip & Flex the Knee

Identify the Muscle.

_^Hamstrings: Semi-membranosus _{^{(bi-articular muscle)}}

• Origin: Ischial Tuberosity

• Insertion: Proximal Tibia

• Action: Extends thigh at hip joint; Flexes leg at knee joint

Identify the Muscle.

_^Hamstrings: Semi-tendinosus _{^{(bi-articular muscle)}}

• Origin: Ischial Tuberosity

• Insertion: Proximal Tibia

• Action: Extends thigh at hip joint; flexes leg at knee joint

Identify the Muscle.

_^Hamstrings: Biceps Femoris (long head) _{^{(bi-articular muscle)}}

• Origin: Ischial Tuberosity

• Insertion: Proximal Fibula

• Action: Extends thigh at hip joint; flexes leg at knee joint

Identify the Muscle.

_^Hamstrings: Biceps Femoris (short head) _{^{(mon-articular muscle)}}

• Origin: Shaft of Femur

• Insertion: Proximal Fibula

• Action: Only Flexes the Knee

_{^{on a model, it is seen underneath the biceps femoris (long head)}}

Identify the Muscle.

Vastus Lateralis _{^{(mon-articular muscle; anterior compartment of the thigh)}}

• Origin: Shaft of Femur

• Insertion: Patella

• Action: Extend Knee

Identify the Muscle.

Vastus Intermedius _{^{(mon-articular muscle; anterior compartment of the thigh)}} * not shown, deep to rectus femoris

• Origin: Shaft of Femur

• Insertion: Patella

• Action: Extend Knee

Identify the Muscle.

Vastus Medialis _{^{(mon-articular muscle; anterior compartment of the thigh}}

• Origin: Shaft of Femur

• Insertion: Patella

• Action: Extend Knee

Identify the Muscle.

Sartorius _{^{(bi-articular muscle)}}

• Origin: Anterior Superior Iliac Spine (ASIS)

• Insertion: Posterior Tibia

• Action: Flex Hip & Flex Knee

Identify the Muscle.

Rectus Femoris _{^{(bi-articular muscle)}}

• Origin: Anterior inferior iliac spine (AIIS)

• Insertion: Patella

• Action: Flex Hip & Extend Knee