Non contractile Knee structures

Sorry for the lack of posting- After finishing my degree I began a research project with Cardiff University looking into human movement.
I have decided to help myself with interview questions I am going to go over the main joint anatomy with some potential issues that may arise.
The first joint I chose to look at is the knee.


The Knee Joint

So my best method to describe the knee joint is from the ground up. I.E bones, connective tissue, muscle, vessels, skin. I am then going to do small installments looking into a few structures in depth, this first post concerns the non contractile anatomy of the knee.
So the knee is a complex pivotal hinge joint- it allows flexion and extension but also some slight twisting. It is the articulation between the femur and the tibia with the fibula connecting to the joint but not becoming involved in the hinge action. On top and central is the patella.













Next are some key non-contractile structures in the knee. Firstly 2 concave pads of cartlidge line the meeting points of the ends of the femur and tibia. These disperse force and reduce friction around the joint.
Ligaments surround the knee to act as stabilizers for the joint. The ACL that originates from deep within the notch of the distal femur and travels to the tibial condyle stops the femur from moving backwards in relation to the tibia (or the tibia moving forward). The PCL connects the posterior intercondylar area of the tibaia to the medial condyle of the femur, stopping the femur from sliding forward on the tibia (or the tibia from sliding backward on the femur). The MCL and LCL(attatches to fib) stop the lateral or medial translation of the femur.

SO far the structures are relatively simple. The articular capsule and bursae are slightly more difficult. The articular capsule or capsular ligament is wide and lax containing the patella, ligaments, menisci and bursae. The capsule consists of synovial and fibrous membrane separated by fatty deposits anteriorly and posteriorly.
The synovial membrane- so the synovial membrane is around the knee, at the front it attatches relatively high up on the femur due to the suprapateller bursa but then attatches close to the carlidge on the tibia.
From behind the membrane is located at the cartilaginous margin of the femoral condyles giving the membrane two dorsal extensions. it passes in front of the ACL and PCL making these both intracapasular but also extra-articular due to the insertions on the cartilage margin of the tibia.
The Fibrous Membrane- this is thin strong and made almost entirely of bands; above and in front, beneath the quadriceps femoris muscle it is strenghtened by tendons surrounding the joint and the fascia lata.





Lastly are the Bursae that are located around the knee. Bursae are crucial for reducing friction where muscles or tendons rub against muscles/tendons/bones and they also dissipate force through a fluid medium. around the knee many bursae can be found:
At the front there is a large subcuaneous pre-patellar bursa between the lower half of the patella and the skin. A small deep infrapatellar bursae between tibia and patella tendon, a subcutanous infrapatellar bursa between the distal part of the tibial tuberosity and the skin and a large supra-patellar bursa between the upper patellar tendon and the femur.
On the lateral aspect there is a bursae between the lateral head of gastrocnemius and the joint capsule, the lateral collateral ligament and tendon of politeus, the lateral collateral and tendoon of biceps femoris, the tendon of poplitues and the lateral femoral condyle.
On the medial aspect there is a bursae that is prolonged from the medial head of gastrocnemius to the semi-membranousus (semi-membranousus bursae) there is a bursae between the MCL and the tendons of saratorius, gracillis and semitendinous (the pes bursae)
On the back the bursae are extremely variable. the clinically important groups are anterior, the pes bursae and the semimembranous bursae.