Knee anatomy 101: What you knee-d to know!
Understanding what lies beneath the surface of the skin can be an incredibly useful tool when it comes to managing an injury. Simply knowing the basic anatomy (ie structure and function) of a joint can really assist you to understand why you may be experiencing your pain.
Today’s focus is on the knee joint.
SKELETON
The knee joint as a whole is actually comprised of 3 smaller joints all within a close approximation. The knee is hinge-type joint meaning it is limited to flexion and extension movement, although there is a very small amount of rotation available as well.
1. Tibio-femoral joint
The biggest of the 3 joints with the femur sitting above and the tibia below
When the foot is planted on the ground, the femur moves on the tibia
When the foot is not planted, the tibia moves on the femur
2. Patello-femoral joint
Comprised of the underside of the patella and the patellofemoral groove of the femur
The patella sits in the groove of the femur and slides up and down as the knee flexes and extends
Can often undergo ‘tracking’ issues where the patella moves outside the borders of the groove
3. Superior tibio-fibula joint
Comprised of the head of the fibula and the tibia
Sits to the bottom-right of the above two joints
Needs to be considered as an indirect contributor to the structure & function of the ankle joint
https://www.memorangapp.com/flashcards/21536/Joints+of+the+Lower+Limb/
https://www.saintlukeskc.org/health-library/how-your-knee-works
LIGAMENTS & CARTILAGE
Due to the number of joints actually contributing to the knee complex, there are quite a number of ligaments present. These all act to limit certain movements in order to prevent dislocations, hyperextensions, and any other extreme movements that go beyond the mechanical design of the knee. Big players when it comes to knee ligaments include:
Medial collateral ligament - limits lateral forces to the knee
Lateral collateral ligament - limits medial forces to the knee
Anterior cruciate ligament - limits forward shear of the lower leg under the femur
Posterior cruciate ligament - limits backward shear of the lower leg under the femur
Medial and lateral meniscus - deepens the groove / creates a socket for the femur to move within
MUSCLES
Muscles acting on the knee joint help to move and/or stabilise the joint. Any muscle which crosses the knee joint has a direct influence on its movement, stability & alignment. This is in comparison to muscles which may not actually cross the joint itself, but act on the foot, lower leg and hip (eg. glutes, muscles that cross the foot and ankle joints etc.) thereby having an indirect effect of the stability and alignment of the knee joint, particularly during movement.
Quadriceps - muscles of the thigh. Comprised of 4 muscles which cross the hip and knee. Help to extend the knee and flex the hip
Hamstrings - group of 3 muscles which are found at the back of the thigh. Act to flex the knee and extend the hip.
Adductors (sartorius, gracillus) - these can be simplified as the groin muscles. They act to bring the leg towards the midline, rotate the lower leg, and help with hip flexion.
Gastrocnemius - flexes the foot and flexes the leg at the knee joint
Peroneals - outwardly rotate (evert) the foot
Popliteus - a small muscle which sits deep, at the back of the knee joint. Acts to ‘unlock’ the knee when moving from an extended to a flexed position.
http://www.osmifw.com/physical-therapy/knee-exercise-conditioning/
There are many more structures to be considered when it comes to knee anatomy however this is a good place to start. Stay tuned as over the next coming weeks we will be investigating the knee joint a little more in relation to common conditions / injuries, management and injury prevention.
