MSK 8 - Anatomy of the Knee Joint Flashcards Preview

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Flashcards in MSK 8 - Anatomy of the Knee Joint Deck (15)
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1
Q

What are the 4 bony surfaces that the knee joint consists of?

A

1) The femoral condyles
2) The tibial condyles
3) Patellar surface of the femur
4) Articular surface of the patella

NB: Fibula is not involved.

2
Q

Which femoral condyle is larger?

What 2 features can be found in-between the femoral condyles?

A
  • The medial femoral condyle is larger and takes more weight.
    1) Anteriorly, there is a trochlear groove, which is more prominent on the lateral lip (a shallow depression for articulation with the patella)
    2) Posteriorly, there is the intercondylar fossa
3
Q

Describe the surface features of the proximal tibia (where it articulates w/the knee joint)

A
  • You have your medial (larger) and lateral condyles, which are smooth surfaces for articulation w/the knee joint.
  • A rough surface in between the condyles which is for attachment of ligaments and other structures (see slide 7)
  • You can also locate the lateral and medial intercondylar tubercles + the intercondylar eminence.
4
Q

What is the patella?

What does it provide to the quadriceps tendon?

A
  • The largest sesamoid bone in the body, embedded into the quadriceps tendon
  • Provides mechanical advantage when extending the knee joint
  • Posterior surface is smooth for articulation with the distal femur.
5
Q

Why is the knee joint not particularly stable on its own?

How is this problem overcome?

A
  • Due to the mismatch of articulating shapes
  • Overcome by tibial menisci which deepen the articular surface of the tibia and by various supporting structures (capsule, ligaments & muscles).
6
Q

Describe the structure + role of the menisci in the knee joint?
Is the medial or lateral menisci more likely to be damaged + why?

A
  • C-shaped plates of fibrocartilage that deepen the surface of articulation for stability + act as shock absorbers.
  • They are wedge shaped (thicker peripherally), attached to the intercondylar area of the tibia.
  • Anteriorly connected by transverse ligament of the knee.
  • Medial meniscus is attached more firmly to other structures so is more likely to be damaged.
7
Q

What are the 3 types of ligaments involved in the knee joint?

A

1) Intra-capsular (cruciate ligaments)
2) Ligaments strengthening the capsule (oblique popliteal)
3) Extra-capsular (collateral ligaments)

8
Q

What are the 2 cruciate ligaments and where do they insert?
What movements do they each limit?
Which one is the strongest

A

1) ACL - passes anteriorly, inserts medially
2) PCL - passes posteriorly, inserts laterally

ACL (weaker) = Limits anterior movement of tibia on femur
PCL (strongest) = limits posterior movement of tibia on femure.

PCL = main stabiliser in weight bearing flexed knee,

9
Q

Describe the anatomical structure of the knee joint capsule.

What is the joint capsule strengthened by?

A
  • Surrounds the side and posterior aspect of the joint, but deficient anteriorly to allow synovial membrane to extend up beneath patella.
  • Strengthened laterally and medially by fibres of the vastus lateralis/medialis.
  • Strengthened obliquely by popliteal ligament (on posterior aspect)
10
Q

What are the 2 main extra-capsular ligaments of the knee joint and their roles?

A

1) Medial collateral ligament - runs from medial femoral condyle to tibia (attaching to medial meniscus). Resists valgus forces (lateral) on tibia.
2) Lateral collateral ligament = runs from lateral femoral condyle to lateral surface of fibula head. Resists varus forces (medial) on tibia

11
Q

What are bursae?

What are the 6 bursae within the knee joint?

A
  • Bursa are fluid filled sacs with a synovial membrane which reduce friction and provide some movement around the joint.
  • Suprapatellar, prepatellar, subcutaneous infrapatellar, deep infrapatellar, semimembranosus + subsartorial.
12
Q

Which muscles provide knee flexion?

A

Hamstrings = biceps femoris, semimembranosus + semitendinosus

Assisted by gracilis, sartorius, popliteus + gastrocnemius.,

13
Q

Which muscles provide knee extension?

A

Quadriceps femoris = rectus femoris, vastus medialis, vastus lateralis + vastus intermedius.

Think about knee extensions - 4 quad muscles being used

14
Q

When can knee rotation occur?

Which muscles provide medial and lateral rotation of the knee?

A
  • When knee is flexed, some rotation can occur (flexion + extension still the primary movements)
  • Medially = Semitendinosus, semimembranosus, gracilis + sartorius
  • Laterally = biceps femoris
15
Q

Describe the mechanism of locking the knee in extension and unlocking in flexion.

A
  • When locking, the femur rotates internally by 5 degrees + cruciate ligaments tighten. Knee becomes more solid column and thigh/leg muscle can relax.
  • When unlocking, popliteus contracts and rotates femur laterally (externally)
  • So when standing up, we lock our knee in extension, and it become unlocked upon flexion.