The vata which has a special tendency to move downwards is called apanavata.
Location of apana vata-
According to charaka, apanavata is located in the testes (Vrshana), Urinary bladder (Vasti), Penis (Medhra), Umbilicus (Nabhi), Thigh (uru), Groin (Vankshana), Rectum (gudam), Lower part of intestine (Antra).
Susruta stated that the apanavata is located in the pakvadhana. Pakavadhana is the receptacle of the fully digested food and also pakvasaya. But there is no such separate receptacle for the fully digested food, since pakvasaya being a place of digestion contains only partly digested food which is received from amasaya and the digestion of such food is completed in this region. The nutrients which are the products of digestion are simultaneously absorbed from the intestine. Therefore pakvadhana can only be assumed as that part of the intestine where the kittabhaga is left at the end of
digestion to be transformed into purisha by the purishdharakala of the koshtha. Therefore pakvadhana may be interpreted as the colon and rectum.
Function of Apana vata-
There is no difference of opinion among the authors regarding the functions of apana vata. They are the following-
To facilitate the excretion of faeces and urine Ejection of the semen
To cause the menstrual flow
To bear down the foetus at the time of delivery