What is the ACL?
The ACL is called the anterior cruciate ligament. Gray's Anatomy (1918) describes it as one of two ligaments that cross inside the knee. Cruciate ligaments were named in older texts by their attachments; modern usage keeps 'anterior' and 'posterior' for the tibial attachment.
What it is
- One of two ligaments that cross inside the knee.
- Named for its position: it runs from the front (anterior) of the tibia to the back of the femur.
- Prevents the tibia from sliding forward on the femur.
Where it is
- Inside the knee joint capsule.
- Crosses the posterior cruciate ligament in an X-shape.
- Runs from the front-middle of the top of the tibia up to the inner side of the outer femoral condyle.
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Last verified: 2026-07-18
- Best Anatomy Answers is an educational reference about human anatomy. It is not medical advice — for any health concern, talk to a licensed medical professional.