Week 2 - Knee joint Flashcards
How many articular surfaces does the knee joint have? Describe it/them
Two
The two surfaces are between the femur condyles and the tibial plateaus, with a non-articular surface between the tibial plateaus, directly below the patella
Which bones participate in the knee joint?
Tibia and femur
Describe possible movement at the knee joint
Uniaxial hinge with a single transverse axis, with slight rotation when semi-flexed
Describe the femur condyles
Femoral condyles have a gradually changing curvature, which is sharper on the posterior side
Medial condyle is bigger than the lateral one.
There’s a large notch between the condyles - intercondylar notch, which is in contact with the patella
Articular cartilage across these surfaces is continuous
Describe the tibial surfaces involved in the knee joint
Shallow depressions that aren’t really condyles are involved. The medial one is again bigger
The depressions themselves are articulated, but the area between them is not - this is a flat projection
Why do we have menisci in the knee joint?
When knee is extended, femoral condyles fit the tibia well
As knee joint is flexed, more of the narrow posterior area comes into contact with tibia, increasing instability
There’s also a much larger space between the bones in this position, which could allow synovial fluid to accumulate in these areas.
The menisci (WFC) on top of the tibial surface, prevents this accumulation and increases stability
Describe menisci in the knee
White fibrocartilage
Crescent shaped for each condyle of the femur
Circumferential side is thick, inner margin is thin and avascular
Tips are attached to intercondylar area, periphery blends with the capsule, becoming more fibrous (as opposed to cartilaginous in the inner margins)
What is the role of the cruciate ligaments?
Provding anteroposterior stability, by maintaining the attachment between tibia and femur during flexion - prevents ‘rolling off’
What are the names of the cruciate ligaments, and how are they named?
Named by attachment to the tibia. If attached anteriorly to the tibia, attach posteriorly to the femur
ACL - anterior cruciate ligament: prevents anterior displacement of tibia
PCL - posterior cruciate ligament
These ligaments cross each other
Describe the medial and lateral collateral ligaments
Medial/Tibial - originates at medial femoral epicondyle, inserts on medial surface of the tibia. A broad deep part blends with the capsule of the knee joint
Lateral/Fibular - originates at lateral femoral epicondyle, inserts at head of fibula. Is seperate from the capsule
Which ligament moves from the knee meniscus to the femur?
Meniscofemoral ligament
Describe the tendon of popliteus muscle
This muscle goes from femur to tibia. The tendon is intra-articular
Which surface of the knee completes its movement before the joint is fully extended?
The smaller, lateral anterior surfaces complete their movement first
–> medial surfaces continue to move after lateral surfaces stop
When does the femur rotate medially?
At the end of extension - the joint cannot be flexed unless rotated externally
Which muscle rotates the knee to unlock extension?
Popliteus
What is an advantage of the locked knee position?
Muscle can relax and the iliotibial tract takes over stabilising
What forms a bony mortise in the ankle joint?
Tibiofibula syndesmoses
What is the bone of the heel?
Calcaneus
Which bone is grasped by the mortise?
The Talus
Which three bones form the ankle joint? What’s the name of this joint?
Tibia, fibula and talus
This is the talocrural joint
In which direction does the top of the foot move in dorsiflexion?
The top of the foot moves up = extension
Describe the difference between inversion and eversion of the foot
Inversion - make the soles face each other
Eversion - turn soles away from each other
Describe the basic bones of the foot
Tarsal bones: talus & calcaneus
Metatarsals - numbered from medial (big toe) side
Phalanges - same pattern as in the hand
Where on the leg would ‘fibular’ or peroneal refer to?
The lateral side of the leg
Where on the leg would plantar refer to? What about dorsal?
Plantar refers to the bottom of the foot
Dorsal refers to the top of the foot
How would an injured cruciate ligament present?
Would be painful when stretched
How would a ruptured cruciate ligament present?
Bone can be moved in the direction not normally allowed by that ligament. Would be relatively unstable
What kind of movement would a patient with an injured PCL present with?
Would not put weight on the semi-flexed knee i.e. if descending stairs, would put injured leg first but keep it straight, and reset for every step
What are the three compartments of the leg muscles?
Anterior, posterior and lateral
What type of muscles are in the anterior compartment of the leg?
Extensors, dorsiflexors of the ankle/toes
What type of muscles are in the posterior compartment of the leg?
One small muscle at the top dedicated to the knee. Rest are flexors, and flexors of the ankle/toe. Only one muscle acts on both knee and ankle
What type of muscles are in the lateral compartment of the leg
Fibular muscles, evertors of the foot
Where do tendons from the posterior compartment enter the ankle?
On the medial side of the ankle
Which muscles plantar flex the ankle?
Gastrocnemius (two heads, one from each epicondylar region)
Soleus - flat sheet from tibia and head of fibia
What is the triceps surae?
The three headed muscle of the calf
Where is the popliteal region?
The back of the knee
What is the plantaris?
A tiny muscle with a long tendon that joins the calcaneal tendon
Which is the deepest muscle of the leg posterior compartment and what does it do?
This is the tibialis posterior, and it’s an inverter of the foot and a plantar flexor
Which muscle in the posterior compartment of the leg is like the profundus of the forearm?
The flexor digitorum longus - it’s a long flexor of the toes, and goes all the way to the distal phalanges
What does the flexor hallucis longus do? What about the extensor hallucis longus
Flexor - this is the long flexor of the big toe
Extensor - long extensor of the big toe
Which is the most medial muscle of the anterior muscles?
Tibialis anterior, a dorsiflexor of the ankle
What’s the name of the long extensor of the toes?
Extensor digitorum longus
What is the difference between extensors of the toes vs the fingers?
All toes have a short extensor in the dorsum of the foot
What is the fibularis tertius?
A small, inconstant dorsiflexor
Describe the two muscles that evert the foot
Both come from fibula
Fibularis longus - crosses sole of foot to the medial side
Fibularis brevis. Sits under longus
Which nerve innervates the posterior compartment of the leg?
Tibial nerve
Which nerve innervates the anterior compartment of the leg?
The deep fibular nerve, which also supplies the skin of the first web
Which nerve innervates the lateral compartment of the leg?
The superficial fibular nerve, which also supplies the skin of the dorsum of the foot
