Institute of Human Anatomy on Instagram: "THE ACL: Your Knee's Front-Line Defense Against Disaster This is what your ACL (anterior cruciate ligament) is actually doing inside your knee joint - and why tearing it is such a big deal. PRIMARY JOB: Stop Forward Slide The ACL prevents "anterior translation" - fancy terms for stopping your tibia (shin bone) from sliding too far forward relative to your femur. Watch how it tightens when we pull the tibia forward on this real cadaver dissection. SECONDA

Institute of Human Anatomy on Instagram: "The Sound of Severe Arthritis: Cartilage vs Bone-on-Bone Listen closely to this real knee joint dissection - the difference in sound tells the whole story. WHAT YOU'RE HEARING: Tapping on remaining cartilage = cushioned sound Tapping on exposed bone = hard, direct contact This is severe arthritis where the protective cartilage has worn away completely in some areas, leaving bone grinding directly on bone with every movement. BEYOND ARTICULAR CARTILAGE: A