many people correctly answered the location where they can find it one of these! but some of them did not explain it what it is so to explain that the hijama is the traditional healthy way of treating some ailments practised by the Prophet Mohammed alaihissalam. This is a technique to extract the blood certain quantities and it will be replaced by the new blood automatically thus removing infiltrated blood from some body parts.
It is widely common among the earlier arabic generation and is getting reduced in new generation due to the reason lack of phisician/or technicial who has expertise to perform this hijaaaaaamas. Good luck.