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Anterior cruciate ligament: anatomy, location and function

The anterior cruciate ligament (ACL) is one of the two cruciate ligaments in the middle of the knee. It stops the tibia from sliding forward on the femur. It prevents anterior dislocation of the tibia on the femur.

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Highlighted in the model: Anterior cruciate ligament. Click any part to read about it, or switch off “Highlight topic” to see the whole body. Use Male / Female to switch bodies. 3D data: BodyParts3D, © The Database Center for Life Science; knee ligaments, menisci, tonsils, palate and parotid glands from the Human Reference Atlas Visible Human Male model and female parts from its Visible Human Female model (HuBMAP / NIH); lung lobes built from the BodyParts3D chest; all CC BY 4.0; meshes simplified and recoloured. The default body is an adult male.

Anterior cruciate ligament at a glance

Also called
ACL
What it is
The anterior cruciate ligament (ACL) is one of the two cruciate ligaments in the middle of the knee. It stops the tibia from sliding forward on the femur.
Location
It attaches to the anterior intercondylar area of the tibia, where it blends with the medial meniscus, and runs upward and backward to the femur in the intercondylar fossa. It crosses the posterior cruciate ligament, which is what cruciate (cross-shaped) refers to.
Function
It prevents anterior dislocation of the tibia on the femur.
Body system
Skeletal · paired (left and right)
FMA ID
FMA44614 (Foundational Model of Anatomy)

Key facts

  • A tear can follow hyperextension of the knee or a large force on the back of a partly flexed knee.
  • The anterior drawer test checks it: if the tibia can be pulled forward on the femur, the ligament is torn.
  • On MRI with the knee nearly straight it rises at about 51° (51.2 ± 3.4° in 70 knees). In this 3D model it rises at only about 30°, because the BodyParts3D femur, a simplified mesh, has a shallow intercondylar notch.

Clinical relevance

With the tibial collateral ligament and the medial meniscus it makes up the unhappy triad, injured together by a force on the outside of an extended knee, as in a rugby tackle.

Structures next to the anterior cruciate ligament

The nearest named structures in the 3D model, measured from the centre of each part:

References

  1. Foundational Model of Anatomy: Anterior cruciate ligament (FMA44614). EMBL-EBI Ontology Lookup Service.
  2. TeachMeAnatomy. The Knee Joint.
  3. Raja B.S. et al. (2020). Assessment of anterior cruciate ligament tibial footprint sagittal diameter and orientation of the ligament: an MRI analysis. Cureus.
  4. OpenStax. Anatomy and Physiology 2e, §7.1 Divisions of the Skeletal System. Rice University, 2022.
  5. Mitsuhashi N. et al. (2009). BodyParts3D: 3D structure database for anatomical concepts. Nucleic Acids Research 37, D782–D785. Data © The Database Center for Life Science, CC BY 4.0.
  6. Browne K., Schlehlein H. (2026). 3D Reference Organ Set for Male, v1.10 (Visible Human Male). Human Reference Atlas 3D Reference Object Library, HuBMAP / NIH. CC BY 4.0.

Related anatomy

Explore the whole body in the interactive 3D human anatomy model, or browse the A–Z list of human structures.