Welcome to our knee joint anatomy demonstration. The knee is the largest joint in the human body, connecting the thigh bone to the shin bone. Let's examine the main bone components that form this complex joint structure.
Now let's examine the major muscle groups surrounding the knee joint. The quadriceps muscles at the front of the thigh extend the knee, while the hamstrings at the back flex it. The gastrocnemius calf muscle assists in knee flexion, and the patellar tendon connects these muscles to provide coordinated movement.
膝关节是人体最大、最复杂的关节之一。它主要由四块骨头组成：股骨、胫骨、腓骨和髌骨。膝关节承担着人体的重量，同时允许腿部进行屈伸和轻微的旋转运动。
膝关节周围有多个重要的肌肉群。股四头肌位于大腿前侧，主要负责伸展膝关节。腘绳肌位于大腿后侧，负责屈曲膝关节。腓肠肌位于小腿后侧，除了控制踝关节外，也辅助膝关节的屈曲运动。
膝关节的稳定性主要依靠多条重要韧带。前后交叉韧带防止胫骨前后滑动，内外侧副韧带提供左右稳定性。半月板起到缓冲减震的作用，而关节软骨则确保关节表面光滑，减少摩擦。
膝关节的主要运动是屈伸运动。正常情况下，膝关节可以从完全伸直的零度位置屈曲到约140度。在不同的屈曲角度下，膝关节承受的负荷和稳定性要求都不同，这需要周围肌肉和韧带的协调配合。
The knee joint primarily performs flexion and extension movements. Normal knee flexion ranges from zero degrees in full extension to approximately 140 degrees in maximum flexion. During movement, the quadriceps muscles extend the knee while the hamstrings flex it, requiring precise coordination between these muscle groups.
To summarize what we have learned about knee joint anatomy: The knee is a complex joint formed by four main bones working together with multiple muscle groups. Ligaments and cartilage provide essential stability and protection, while the joint allows flexion from zero to 140 degrees through coordinated muscle action. Understanding this anatomy is crucial for maintaining knee health and preventing injuries.