The Knee Joint

Question 1

What type of joint is the knee joint?

Answer 1

A bicondylar type synovial joint

Question 2

What articulations form the knee joint?

Answer 2

Articulations between the patella, femur and tibia

Question 3

The knee joint consists of two articulations. What are they?

Answer 3

Tibiofemoral - the medial and lateral condyles of the femur articulating with the tibia (this is the weight-bearing joint of the knee)
Patellofemoral - the anterior and distal part of the femur articulating with the patella (allows the tendon of the quadriceps femoris (main extensor of the knee) to be inserted directly over the knee, increasing the efficiency of the muscle).

Question 4

What are both joint surfaces lined with and enclosed in?

Answer 4

Hyaline cartilage, and enclosed within a single joint cavity

Question 5

What is special about the patella?

Answer 5

The patella is formed inside the tendon of the quadriceps femoris; its presence minimises wear and tear on the tendon.
It is a sesamoid bone.

Question 6

Describe the neurovasculature of the knee joint

Answer 6

Blood supply - genicular anastomoses around the knee, which are supplied by the genicular branches of the femoral and popliteal arteries
Nerve supply - femoral, tibial and common fibular nerves

Question 7

What are Menisci?

Answer 7

The knee has medial and lateral menisci, which are C shaped fibrocartilage structures, attached at both ends to the intercondylar area of the tibia

Question 8

What are the functions of the Menisci?

Answer 8

To deepen the articular surface of the tibia, thus increasing stability of the joint
To act as shock absorbers

Question 9

What is special about the medial meniscus?

Answer 9

In addition to the intercondylar attachment, the medial meniscus is fixed to the medial collateral ligament and the joint capsule. Any damage to the medial collateral ligament results in tearing of the medial meniscus.
The lateral meniscus is smaller and doesn’t have any extra attachments, so it’s fairly mobile.

Question 10

What are bursae?

Answer 10

A bursa is a synovial fluid filled sac, found between moving structures in a joint - with the aim of reducing wear and tear on those structures.

Question 11

How many bursae are around the knee joint?

Answer 11

4

Question 12

Name the bursae around the knee joint

Answer 12

Suprapatella bursa - this is an extension of the synovial cavity of the knee, located between the quadriceps femoris and the femur
Prepatella bursa - found between the apex of the patella and the skin
Infrapatella bursa - split into deep and superficial. The deep bursa lies between the tibia and the patella ligament. The superficial lies between the patella ligament and the skin.
Semimembranosus bursa - located posteriorly in the knee joint, between the semimembranosus muscle and the medial head of the gastrocnemius

Question 13

How many ligaments are there in the knee joint?

Answer 13

3

Question 14

Name the major ligaments in the knee joint

Answer 14

Patellar ligament - a continuation of the quadriceps femoris tendon distal to the patella. It attaches to the tibial tuberosity
Collateral ligaments - these are two strap-like ligaments. They act to stabilise the hinge motion of the knee, preventing any medial or lateral movement
Cruciate ligaments - these two ligaments connect the femur to the tibia. They cross each other.

Question 15

Describe the medial collateral ligament

Answer 15

A wide and flat ligament, found on the medial side of the joint. Proximally, it attaches to the medial epicondyle of the femur, distally it attaches to the medial surface of the tibia

Question 16

Describe the lateral collateral ligament

Answer 16

Thinner and rounder than the medial collateral, this attaches proximally to the lateral epicondyle of the femur, distally it attaches to a depression on the lateral surface of the fibular head

Question 17

Describe the anterior cruciate ligament

Answer 17

Attaches at the anterior intercondylar region of the tibia and ascends posteriorly to attach to the femur, in the intercondylar fossa. It prevents anterior dislocation of the tibia onto the femur

Question 18

Describe the posterior cruciate ligament

Answer 18

Attaches at the posterior intercondylar region of the tibia, and ascends anteriorly to attach to the femur in the intercondylar fossa. It prevents posterior dislocation of the tibia onto the femur