Lower limb
Anterior cruciate ligament (ACL)
Ligamentum cruciatum anterius (ACL)
- Origin
- Posteromedial aspect of the lateral femoral condyle within intercondylar notch
- Insertion
- Anterior intercondylar area of tibial plateau (runs anteromedially and distally)
- Function
- Primary passive restraint against anterior tibial translation (85% total resistance) and secondary stabilizer against internal rotation and varus/valgus stress; consists of anteromedial (AM) and posterolateral (PL) bundles
- Innervation
- Posterior articular branch of tibial nerve (rich in Ruffini, Golgi, and Pacinian mechanoreceptors)
- Movement & chain
- Governs femoral rollback and the terminal 'screw-home' external tibial rotation mechanism
- Palpation
- Intra-articular (extrasynovial), non-palpable
- Clinical
- ACL tear (classic non-contact deceleration/pivoting injury with audible 'pop', acute hemarthrosis, and giving-way sensation); positive Lachman test, Anterior Drawer, and Pivot-shift tests; O'Donoghue's unhappy triad.
- Segmental innervation
- L3–S1
- In clinical practice
- Lachman test, post-ACL reconstruction functional milestones, neuromuscular jump-landing training, and Return-to-Sport battery testing
- Region in the model
- Lower limb