The knee joint is the connection of 3 bones:
The meniscus is a structure that sits within the knee joint to support it and help absorb shock. The knee is meant to be a stable joint, so the muscles and ligaments work together to decrease any rotational or extreme motions.
- Anterior cruiciate ligament (ACL)
- Posterior cruciate ligament (PCL)
- Fibular collateral ligament (FCL)
- Tibial collateral ligament (TCL)
NOTE: FCL is also called the LCL (lateral collateral ligament) and TCL is also called the MCL (medial collateral ligament).
The patella sits anterior to the knee joint and is held in place by the quadriceps tendon and patellar tendon. The main function of the patella is to increase the amount of force produced by the quadriceps. It can also be a major source of knee pain if it doesn’t move along the knee joint properly, usually from muscle/IT band tightness and/or muscle weakness.
* Click on the images below to see the muscles surrounding the knee.
NOTE: the quadriceps and hamstrings are actually groups of multiple muscles:
- Quadriceps: rectus femoris, vastus lateralis, vastus medialis, vastus intermedius.
- Hamstrings: semitendinosus, semimembranosus, biceps femoris.
As you can see, the IT band also crosses the knee joint. Even though it is not a muscle, it can have a huge affect on the function of the knee when it becomes tight. Just another reason to bond with your foam roller!
Major muscles surrounding the knee, categorized by function:
- Flexion: hamstrings and gastrocnemius.
- Extension: quadriceps.
Created by: Missy Albrecht DPT, CSCS, FMS
Reference: Dutton, Mark. Orthopaedic Examination, Evaluation, and Intervention. Second edition. The McGraw-Hill Companies, Inc, 2008: 932-1059.