Anatomy of the knee

Question 1

What 4 parts of the knee joint help to maintain stability

Answer 1

• Menisci
• Membranes
• Ligaments
• Muscles and tendons

Question 2

How does torn menisci occur

Answer 2

Excessive rotation on a
flexed knee can cause
tearing of the menisci,
most frequently the
medial meniscus
* Often occurs in
conjunction with a torn
anterior cruciate ligament
or tibial collateral ligament

Question 3

What is clergyman’s knee and housemaids knee

Answer 3

Clergyman’s knee
– Infrapatellar bursitis
* Housemaid’s knee
– Prepatellar bursitis

Question 4

What are the anterior and posterior cruciate ligaments

Answer 4

Looks like a cross in the middle

Anterior Cruciate
(limits extension,
prevents anterior
displacement of the
tibia and assists the
posterior cruciate in
limiting medial
rotation of the tibia)

Posterior cruciate
(limits flexion, prevents
posterior displacement
of the tibia; main
stabiliser of a weightbearing flexed knee)

Question 5

Muscles crossing knee- popliteus

Answer 5

Origin – lateral femoral condyle
* Insertion – posterior surface of
proximal tibia
* Innervation – tibial nerve (L4 –
S1)
* Action – stabilizes knee joint
(resists lateral rotation of tibia
on femur) and unlocks knee
joint (laterally rotates femur on
fixed tibia)

Question 6

What is locking and unlocking of the knee

Answer 6

Locking is caused by the cruciate
ligaments; it causes the
collateral ligaments to tighten
and articular surfaces to move
into a stable position
* Unlocking is caused by the
popliteus muscle laterally
rotating the femur relative to
the tibia

Question 7

Arteries in the knee

Answer 7

Genicular anastomosis –

– Large anastomosis around knee
– Branches from:
– Popliteal artery
– Femoral artery
– Lateral circumflex femoral
artery
– Anterior tibial artery
– Four branches from the popliteal
artery:
– Superior medial genicular a.
– Superior lateral genicular a.
– Inferior medial genicular a.
– Inferior lateral genicular a.

Knee is innervated by branches
from obturator, femoral, tibial
and common fibular nerves

Question 8

What happens in occlusion of femoral artery

Answer 8

Occlusion of femoral artery –
* Before branching of profunda
femoris
– Blood to leg via the inferior
gluteal artery and cruciate
anastomosis
* After branching of profunda femoris
– Blood to leg via the lateral
circumflex femoral artery and
genicular anastomosis.

Question 9

What are the boundaries of the popliteal fossa

Answer 9

Superolateral – biceps femoris
* Superomedial – semimembranosus and semitendinosus
* Inferolateral – lateral head of gastrocnemius and plantaris
* Inferomedial – medial head of gastrocnemius
* Floor – popliteal surface of femur and joint capsule
* Roof – skin and fascia

Question 10

What are the contents of the popliteal fossa

Answer 10

Contents (medial to lateral, deep to
superficial)

• Popliteal artery
• Popliteal vein
• Tibial nerve
• Common fibular nerve
• Also:
• Genicular branches
• Lymph
• Fat
• Medial and lateral sural cutaneous
  branches may come off in the fossa
  Roof
• Small saphenous vein
• Posterior cutaneous nerve of thigh
  The popliteal artery is deep to both
  the vein and tibial nerve; it can be
  felt by pushing hard on the superior
  part of the fossa.