Muscles of the Knee

Mr. Brewer

Muscles of the KneeQuadriceps (4) –- Vastus Medialis - Vastus Intermediate- Vastus Lateralis- Rectus Femoris Insertion/Origin:- Distal insertion of all quadricep

muscles are located at the tibial tuberosity via the quadricep tendon.

- The 3 vastus quadricep muscles attach superiorly to the proximal portion of the Femur WITHOUT crossing the hip joint.

Muscles

- Vastus Muscles- Do NOT cross the hip joint.- Because of that, they are only responsible for knee

extension.- VMO (Vastus Medialis Oblique) is an important

muscle to focus on rehabbing following major knee surgery.- Responsible for the last 15 degrees of Knee Extension,

also known as “Terminal Knee Extension”- https://www.youtube.com/watch?v=ZscBVtoX62U

Rectus Femoris

Rectus Femoris: - The most superficial of the

quadricep muscles- Important to recognize when

considering treatment options.- Responsible for not only knee

extension, like the rest of the quadricep muscles, but also HIP Flexion.

- This is because the Rectus Femoris crosses the hip joint and attaches proximally to the anterior inferior iliac spine of the hip bone.

Muscles

- Rectus Femoris:- The Rectus Femoris is the only Quadricep to cross

both the knee AND hip joints.- Therefore the Rectus Femoris not only is involved

in Knee extension, but also Hip Flexion.- Video showing hip flexion exercises and

movements, along with techniques for stretching:- https://www.youtube.com/watch?v=eVbmiI4YSdU

Hamstring Muscles

HamstringHamstring Muscles (3):- Biceps Femoris

- Lone lateral hamstring muscle- “Biceps” meaning 2 heads- Distally:

- the biceps femoris does cross the knee joint and both the short-head and long-head come together and attach to the Head of the Fibula.

- Proximally:- Long-head crosses the hip joint

and attaches to the pelvis.- Short-head attaches to the

posterior femur along the middle 1/3.

* Both heads are active with knee flexion, but the long-head assists with Hip-extension as well.

Hamstrings

- Semitendinosus and Semimembranosus- Medial Hamstring muscles- Both originate proximally

to the ischial tuberosity of the pelvic bones.

- Both insert distally to the medial surface of the tibia.

Hamstring Action (at the knee)

• Knee Flexion:– All 3 of the Hamstring

muscles have roles in Knee Flexion.

– C1 and C2 is an example of “bilateral knee flexion”

– E1 and E2 are examples of “unilateral knee flexion”

– F1 and F2 are examples of “bilateral knee flexion” (focusing on the eccentric contractions of the hamstring muscles)

Pes Anserine

The Pes Anserine is located on the anterior, superior and medial aspect of the tibia just below the knee joint line.

It is the location of the insertion of 3 important muscles.

Pes Anserine is Latin for “Goose foot”

The 3 muscles that insert at the Pes Anserine are abbreviated SGT.(Sartorius, Gracilis and SemiTendinosus)

SartoriusThe “S” in SGT.

The Sartorius is the longest muscle in the body.

The proximal insertion is the ASIS of the hip (Anterior Inferior Iliac Spine)

It creates a movement that is a combination of hip flexion and hip External rotation. (Figure – 4 position)

Watch:http://www.screenr.com/1sys

GracilisThe “G” in SGT.

The Gracilis is primarily a HIP ADDUCTOR.

Due to the fact that the gracilis cross the knee joint, it also plays a major roll in assisting to stabilize the knee joint on the medial aspect.

The proximal insertion point of the gracilis is along the ischium of the hip bone(s).

Watch:https://www.youtube.com/watch?v=95MY5Xjvtqs

SemiTendinosus

The “T” in SGT.

We discussed the major points of the semitendinosus along with the other hamstring muscles on previous slides.

Popliteus

The Popliteus is a very small muscle located in the posterior aspect of the knee.

The popliteus crosses the knee joint, attaching to the femur laterally and wrapping around the posterior aspect of the leg to attach to the medial aspect of the Tibia.

The popliteus assists in Knee Flexion.

It is said to be the muscle that “unlocks” the knee from full extension when initiating knee flexion.