Week 5: Menisci & Knee Joint Motion

Question 1

Describe the shape of the medial and lateral menisci when viewed from above:

Answer 1

• Medial: Larger and more oval (C shaped) than the lateral menisci
• Lateral: Nearly circular

Question 2

What are the specific attachment sites of the medial meniscus?

Answer 2

• Anterior horn: Anterior intercondylar area of tibia in front of the ACL
• Posterior horn: Posterior intercondylar area in front of the PCL
• Margin: To joint capsule & deeper fibers of the MCL

Question 3

What are the specific attachment sites of the lateral meniscus?

Answer 3

• Anterior horn: Anterior intercondylar area lateral to and behind attachment of ACL
• Posterior horn: Posterior intercondylar area in front of the end of the medial meniscus
• Margin: To joint capsule

Question 4

What is the unhappy triad?

Answer 4

Trauma to the knee joint which results in injury of the medial meniscus, MCL and ACL

Question 5

What is the role of the coronary ligaments?

Answer 5

Attaches menisci to the tibial plateau and knee joint capsule

Question 6

Describe the shape of the menisci when viewed in the coronal plane:

Answer 6

Wedge shaped; thicker at their external margins and taper to thin unattached edges in the interior of the joint

Question 7

Why are the upper surfaces of the menisci slightly concave?

Answer 7

Deepen the articular fossae for the reception of the convex femoral condyles

Question 8

What are some of the functions of the menisci?

Answer 8

• Distribution of loads
• Improve congruence
• Aid in stability of the joint/shock absorption
• Aid in distribution of synovial fluid (joint nutrition)

Question 9

Describe the vascular supply to the menisci and the implications of this supply to healing:

Answer 9

Outer 1/3 well vascularised, therefore tears to the inner 2/3rds do not heal well

Question 10

Describe the gross structure and function of the transverse ligament:

Answer 10

• Band of transverse fibres joining the anterior horns of the menisci
• May be absent, or sometimes a second intermeniscal ligament is present at the posterior horns

Question 11

Describe the motion of the femoral condyles relative to the tibial articular surfaces (arthrokinematics) during extension and flexion (osteokinematics) at the knee joint:

Answer 11

• Extension:
  Femoral condyles roll anteriorly and translate posteriorly
• Flexion:
  Femoral condyles roll posteriorly and translate anteriorly

Question 12

Why do the menisci move slightly forward during extension of the knee joint?

Answer 12

The femoral condyles (passively) push the menisci forwards during extension and surrounding ligaments also contribute to pulling the menisci anteriorly

Question 13

Why do the menisci move slightly backward during flexion of the knee joint?

Answer 13

They are pulled posteriorly via attachments to muscles which contract – popliteus (lateral), semimembranosus expansion (medial)

Question 14

What ligament attaches the meniscus to the patella?

Answer 14

Patellomeniscal/meniscopatellar ligament