What about the pipa in the costume novels?

Pipa is the clavicle, shoulders and bones through which blood vessels pass. Look at the clavicle and imagine the curve on the side of the pipa, and you will understand why it is called pipa. Passing a chain or hook through the clavicle will not lead to massive bleeding and death, nor will it affect walking, nor will it waste upper limbs, nor will it resist, and it can effectively prevent escape. It can be said that it is the most convenient, economical, effective and reliable non-lethal means to escort or guard prisoners.

Therefore, this bone is simply called "lock" bone!

You can feel it. The skin covered on this bone is so thin that there is almost no muscle and fat layer to protect it. It is convenient for the iron chain to pass through the pipa bone, which is not easy to escape, and it is not so deadly (firstly, it should be disinfected with red iron wire, and when operating, it should be careful to avoid big blood vessels and stay away from important organs, so it is not easy to get hurt), which can effectively restrain the body and make it difficult to play one's kung fu.

The human body really can't find a second bone structure suitable for this.