Knee Joint Anatomy: Bones, Ligaments, and Key Structures

Anatomy of the Human Knee

The knee is the largest and most complex synovial joint, comprising four bones and a network of ligaments, menisci, tendons, and muscles.

Bones

• Femur (thigh bone): Distal end forms medial and lateral condyles articulating with tibia.
• Tibia (shin bone): Proximal plateau bears weight; medial plateau larger.
• Fibula: Lateral to tibia; not part of the main joint but provides ligament attachment.
• Patella (kneecap): Sesamoid bone in the quadriceps tendon; increases leverage.

Key Soft-Tissue Structures

• Menisci (medial & lateral): Fibrocartilage wedges that deepen the tibial plateau, absorb shock, and distribute load.
• Ligaments: ACL, PCL (cruciates); MCL, LCL (collaterals).
• Extensor mechanism: Quadriceps tendon → patella → patellar tendon → tibial tuberosity.
• Joint capsule & synovium: Produce lubricating synovial fluid.
• Bursae: Prepatellar, infrapatellar, suprapatellar—reduce friction.

Function

Allows flexion/extension (~0–135°), slight rotation in flexion. Stability relies on ligamentous and muscular control.