膝关节连接大腿和小腿，由两个关节组成：一个在大腿骨和小腿骨之间，另一个在大腿骨和膝盖骨之间。
The knee joint connects the thigh and the shank and consists of two joints: one between the thigh bone and the shank bone, and the other between the thigh bone and the kneecap.
