Knee
The knee joint
is made of three bones: the femur (the thigh bone), the
tibia (the larger of the two lower leg bones), and the
patella (the kneecap). Where any two bones come together
is a joint. There are two joints in the knee: the patellofemoral
joint (where the kneecap glides on the thigh bone) and the
tibiofemoral joint (where the thigh bone meets the lower
leg). Both of these joints are extremely important in the function
of the knee.
The patellofemoral
joint is a gliding joint. The kneecap floats over the knee
providing a fulcrum for the quadriceps muscle complex to
concentrate its force to extend (straighten) the knee. The kneecap
must follow a specific track to function properly.
The tibiofemoral
joint is known as a hinge joint. This title is a bit misleading,
since this joint does not act like the simple hinge on a door. The
two bones not only hinge on each other, they also slide and spin.
The joint is actually held together by muscles and four major ligaments:
the lateral collateral ligament (LCL – controlling
side-to-side movement), the medial collateral ligament
(MCL – controlling side-to-side movement), the anterior cruciate
ligament (ACL – controlling forward movement of the tibia and
twisting), and the posterior cruciate ligament (PCL - controlling
backward movement of the tibia and twisting). There are two shock
absorbers cushioning the knee joint called the medial and
lateral meniscus.
The major muscles
attaching to the knee are the hamstrings (biceps femoris,
semitendonosus, and semimembanosus), the quadriceps
(rectus femoris, vastus lateralis, vastus
medialis, and vastus intermedialis), the gracilis,
the gastrocnemius, the sartorius, and the iliotibial
band.
Click on the
links above to learn more about some common knee injuries. This
list is not exhaustive and is not designed to diagnose or treat
any pathology. If you suspect a knee injury, you should seek a formal
evaluation by a licensed sports medicine professional.
Hip
| Knee | Shoulder
