Knees are one the more troublesome joints of the body especially for athletes or elderly whose knee has been subject to a lot of wear and tear. Having personally torn an ACL (anterior cruciate ligament) and meniscus, the knee is probably my least favorite joint and I catch myself saying ****ing knees a bit too much… However this has also motivated me to learn a lot more about how the knees work, and the reason why this is the first of many musculoskeletal system anatomy articles.
The knee is classified as a hinge joint which are formed between two or more bones and is limited to movement along one axis (flexion or extension). Fun fact: The knee is the largest and most complex synovial joint of the body (hinge is a common synovial joint class). However because of the complexity of the knee joint it may also be referred to as a “modified” hinge, bicondylar as well as biaxial joint. It might a good idea to check with your lecturer if you are at university.
The joint articulates between the femur and the tibia as well as the femur and patella. Flexion of the knee pulls the tibia posteriorly and extension pushes it anteriorly. Now this is where the complexity of the knee comes in, as during flexion the knee may rotate both laterally and medially, and during extension (standing position) the femur will rotate the knee medially to lock the knee into position (you can see this very well if you hyperextend your knee, but no over-hyperextension experiments please as that is painful). To unlock the knee the femur will rotate it laterally.
Now that the basics of the knee joint itself has been covered let us take a closer look at the landmarks of the knee and their functions:
*Femoral condyles at the articulate surfaces (posterior side of knee)- One medial, one lateral. The femoral condyles have an intercondylar fossa that separates them, which is home to the proximal attachment points of the anterior and posterior cruciate ligaments (ACL and PCL)
*Epicondyles – upper portion of the femoral condyles. These are home to the proximal attachment of the lateral and medial collateral (NOTE: NOT CRUCIATE) ligaments (LCL and MCL). The MCL (medial) is of course on the medial condyle 🙂 These bad boy ligaments are also known as fibular and tibial according which side they are on. The lateral collateral is for example on the same side as the fibula as the fibula is the most lateral of the fibula and tibia (yay, easypiecy).
*Tibial Plateu – Superior proximal surface of the tibia. Has a couple tibial condyles (medial and lateral) at the articulate surfaces. These condyles also has an intercondylar region between them which is where the cartilage of the menisci as well as the ACL and PCL.
*Intercondylar eminence – The point thing that sticks out of the superior surface of the tibia. The point thing also has two other pointy things, which are the lateral and medial intercondylar tubercle.
Continued in Part 2…