middle finger cun

例句：

1. 1. He pointed to the middle finger of his left hand as he spoke.
   他指着自己的左手的中指说话。
2. 2.The doctor examined her middle finger joint for swelling.
   医生检查了她的中指关节是否有肿胀。
3. 3. When she held her hand up, you could see the middle finger cun clearly.
   当她举起手时，你可以清楚地看到中指关节。