He cracked the joints of his fingers.

他把手指关弄得劈啪作。

Our fingers bend at the knuckle.

手指在指关弯曲。

His arm looks like a broken compass;it's not an arm any more, but a knucklebone with a shank attached.

他胳膊活像一只破损指南针，早已不再是一条胳膊，却成加上一条胫骨指关。

The most common type of joint in the human body is the diarthrodial joint -- knuckles and shoulders are examples -- in which two bones come together in a capsule.

人体中最常见关是运动关，如指关和肩关等，关一个囊状物把两根骨头结合在一起。